1
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Shibukawa A, Higuchi R, Song G, Mikami H, Sudo Y, Jang M. Large-volume focus control at 10 MHz refresh rate via fast line-scanning amplitude-encoded scattering-assisted holography. Nat Commun 2024; 15:2926. [PMID: 38589389 PMCID: PMC11001868 DOI: 10.1038/s41467-024-47009-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 03/11/2024] [Indexed: 04/10/2024] Open
Abstract
The capability of focus control has been central to optical technologies that require both high temporal and spatial resolutions. However, existing varifocal lens schemes are commonly limited to the response time on the microsecond timescale and share the fundamental trade-off between the response time and the tuning power. Here, we propose an ultrafast holographic focusing method enabled by translating the speed of a fast 1D beam scanner into the speed of the complex wavefront modulation of a relatively slow 2D spatial light modulator. Using a pair of a digital micromirror device and a resonant scanner, we demonstrate an unprecedented refresh rate of focus control of 31 MHz, which is more than 1,000 times faster than the switching rate of a digital micromirror device. We also show that multiple micrometer-sized focal spots can be independently addressed in a range of over 1 MHz within a large volume of 5 mm × 5 mm × 5.5 mm, validating the superior spatiotemporal characteristics of the proposed technique - high temporal and spatial precision, high tuning power, and random accessibility in a three-dimensional space. The demonstrated scheme offers a new route towards three-dimensional light manipulation in the 100 MHz regime.
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Affiliation(s)
- Atsushi Shibukawa
- Research Institute for Electronic Science, Hokkaido University, Sapporo, 001-0020, Japan
| | - Ryota Higuchi
- Research Institute for Electronic Science, Hokkaido University, Sapporo, 001-0020, Japan
| | - Gookho Song
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea
| | - Hideharu Mikami
- Research Institute for Electronic Science, Hokkaido University, Sapporo, 001-0020, Japan.
| | - Yuki Sudo
- Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, 700-8530, Japan.
| | - Mooseok Jang
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, Daejeon, 34141, Republic of Korea.
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2
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Cremaschini S, Cattelan A, Ferraro D, Filippi D, Marinello F, Meggiolaro A, Pierno M, Sada C, Zaltron A, Umari P, Mistura G. Trifurcated Splitting of Water Droplets on Engineered Lithium Niobate Surfaces. ACS APPLIED MATERIALS & INTERFACES 2024; 16:4271-4282. [PMID: 38194671 PMCID: PMC10811617 DOI: 10.1021/acsami.3c16573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2023] [Revised: 12/22/2023] [Accepted: 12/26/2023] [Indexed: 01/11/2024]
Abstract
Controlled splitting of liquid droplets is a key function in many microfluidic applications. In recent years, various methodologies have been used to accomplish this task. Here, we present an optofluidic technique based on an engineered surface formed by coating a z-cut iron-doped lithium niobate crystal with a lubricant-infused layer, which provides a very slippery surface. Illuminating the crystal with a light spot induces surface charges of opposite signs on the two crystal faces because of the photovoltaic effect. If the light spot is sufficiently intense, millimetric water droplets placed near the illuminated spot split into two charged fragments, one fragment being trapped by the bright spot and the other moving away from it. The latter fragment does not move randomly but rather follows one of three well-defined trajectories separated by 120°, which reflect the anisotropic crystalline structure of Fe:LiNbO3. Numerical simulations explain the behavior of water droplets in the framework of the forces induced by the interplay of pyroelectric, piezoelectric, and photovoltaic effects, which originate simultaneously inside the illuminated crystal. Such a synergetic effect can provide a valuable feature in applications that require splitting and coalescence of droplets, such as chemical microreactors and biological encapsulation and screening.
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Affiliation(s)
- Sebastian Cremaschini
- Dipartimento di Fisica e
Astronomia “G. Galilei”, Università
di Padova, Via Marzolo 8, 35131 Padova, Italy
| | - Alberto Cattelan
- Dipartimento di Fisica e
Astronomia “G. Galilei”, Università
di Padova, Via Marzolo 8, 35131 Padova, Italy
| | - Davide Ferraro
- Dipartimento di Fisica e
Astronomia “G. Galilei”, Università
di Padova, Via Marzolo 8, 35131 Padova, Italy
| | - Daniele Filippi
- Dipartimento di Fisica e
Astronomia “G. Galilei”, Università
di Padova, Via Marzolo 8, 35131 Padova, Italy
| | - Filippo Marinello
- Dipartimento di Fisica e
Astronomia “G. Galilei”, Università
di Padova, Via Marzolo 8, 35131 Padova, Italy
| | - Alessio Meggiolaro
- Dipartimento di Fisica e
Astronomia “G. Galilei”, Università
di Padova, Via Marzolo 8, 35131 Padova, Italy
| | - Matteo Pierno
- Dipartimento di Fisica e
Astronomia “G. Galilei”, Università
di Padova, Via Marzolo 8, 35131 Padova, Italy
| | - Cinzia Sada
- Dipartimento di Fisica e
Astronomia “G. Galilei”, Università
di Padova, Via Marzolo 8, 35131 Padova, Italy
| | - Annamaria Zaltron
- Dipartimento di Fisica e
Astronomia “G. Galilei”, Università
di Padova, Via Marzolo 8, 35131 Padova, Italy
| | - Paolo Umari
- Dipartimento di Fisica e
Astronomia “G. Galilei”, Università
di Padova, Via Marzolo 8, 35131 Padova, Italy
| | - Giampaolo Mistura
- Dipartimento di Fisica e
Astronomia “G. Galilei”, Università
di Padova, Via Marzolo 8, 35131 Padova, Italy
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3
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Wu J, Li X, Lin T, Zhuang L, Tang B, Liu F, Zhou G. Electric-Field-Induced Selective Directed Transport of Diverse Droplets. ACS APPLIED MATERIALS & INTERFACES 2024; 16:4126-4137. [PMID: 38191293 DOI: 10.1021/acsami.3c13792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2024]
Abstract
Droplet directional transport is one of the central topics in microfluidics and lab-on-a-chip applications. Selective transport of diverse droplets, particularly in another liquid phase environment with controlled directions, is still challenging. In this work, we propose an electric-field gradient-driven droplet directional transport platform facilitated by a robust lubricant surface. On the platform, we clearly demonstrated a liquid-inherent critical frequency-dominated selective transport of diverse droplets and a driving mechanism transition from electrowetting to liquid dielectrophoresis. Enlightened by the Kelvin-Helmholtz theory, we first realize the directional droplet transport in another liquid phase whenever a permittivity difference exists. Co-transport of multiple droplets and various combinations of droplet types, as well as multifunctional droplet transport modes, are realized based on the presented powerful electric-field gradient-driven platform, overcoming the limitations of the surrounding environment, liquid conductivity, and intrinsic solid-liquid wetting property existing in traditional droplet transport strategies. This work may inspire new applications in liquid separation, multiphase microfluidic manipulation, chemical reagent selection, and so on.
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Affiliation(s)
- Junjun Wu
- National Center for International Research on Green Optoelectronics, Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Xinyu Li
- National Center for International Research on Green Optoelectronics, Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Tao Lin
- National Center for International Research on Green Optoelectronics, Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Lei Zhuang
- National Center for International Research on Green Optoelectronics, Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Biao Tang
- National Center for International Research on Green Optoelectronics, Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Feilong Liu
- National Center for International Research on Green Optoelectronics, Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Guofu Zhou
- National Center for International Research on Green Optoelectronics, Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
- Shenzhen Guohua Optoelectronics Tech. Co. Ltd., Shenzhen 518110, P. R. China
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4
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Orejon D, Maeda Y, Zhang P, Lv F, Takata Y. Nanorough Is Not Slippery Enough: Implications on Shedding and Heat Transfer. ACS APPLIED MATERIALS & INTERFACES 2024; 16:1779-1793. [PMID: 38164911 PMCID: PMC10788867 DOI: 10.1021/acsami.3c14232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 12/08/2023] [Accepted: 12/11/2023] [Indexed: 01/03/2024]
Abstract
Lowering droplet-surface interactions via the implementation of lubricant-infused surfaces (LISs) has received important attention in the past years. LISs offer enhanced droplet mobility with low sliding angles and the recently reported slippery Wenzel state, among others, empowered by the presence of the lubricant infused in between the structures, which eventually minimizes the direct interactions between liquid droplets and LISs. Current strategies to increase heat transfer during condensation phase-change relay on minimizing the thickness of the coating as well as enhancing condensate shedding. While further surface structuring may impose an additional heat transfer resistance, the presence of micro-structures eventually reduces the effective condensate-surface intimate interactions with the consequently decreased adhesion and enhanced shedding performance, which is investigated in this work. This is demonstrated by macroscopic and optical microscopy condensation experimental observations paying special attention at the liquid-lubricant and liquid-solid binary interactions at the droplet-LIS interface, which is further supported by a revisited force balance at the droplet triple contact line. Moreover, the occurrence of a condensation-coalescence-shedding regime is quantified for the first time with droplet growth rates one and two orders of magnitude greater than during condensation-coalescence and direct condensation regimes, respectively. Findings presented here are of great importance for the effective design and implementation of LISs via surface structure endowing accurate droplet mobility and control for applications such as anti-icing, self-cleaning, water harvesting, and/or liquid repellent surfaces as well as for condensation heat transfer.
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Affiliation(s)
- Daniel Orejon
- Institute
for Multiscale Thermofluids, School of Engineering, University of Edinburgh, Scotland EH9 3BF, United
Kingdom
- International
Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Yota Maeda
- Department
of Mechanical Engineering, Thermofluid Physics Laboratory, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Peng Zhang
- Institute
of Refrigeration and Cryogenics, Shanghai
Jiao Tong University, Shanghai 200240, China
| | - Fengyong Lv
- School
of Urban Construction and Safety Engineering, Shanghai Institute of Technology, Shanghai 201418, China
| | - Yasuyuki Takata
- Institute
for Multiscale Thermofluids, School of Engineering, University of Edinburgh, Scotland EH9 3BF, United
Kingdom
- International
Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
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5
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Goel S, Pillai DS. Reduced-Order Model for Surfactant-Laden Electrified Sessile Droplets. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:15177-15188. [PMID: 37852302 DOI: 10.1021/acs.langmuir.3c01596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2023]
Abstract
A comprehensive understanding of the physics of electrowetting of a surfactant-laden droplet is important for applications in rapid healthcare diagnostics. A majority of biological samples examined during point-of-care (POC) diagnostics are biofluids with dissolved surfactants, such as the respiratory droplets containing protein (mucin) and surfactant molecules like dipalmitoylphosphatidylcholine. The presence of these surfactant molecules is anticipated to have a significant impact on the performance of electrowetting-based POC diagnostic devices. A reduced-order model is developed using the weighted residual integral boundary layer theory for the electrowetting of a surfactant-laden sessile droplet in a parallel plate electrode configuration. Thin film evolution equations are obtained for the fluid-fluid interface, the surfactant concentration, the depth-integrated flow rate, and the interfacial charge density. We show that the presence of surfactants opposes and decreases the strength of the electrohydrodynamic flow due to Marangoni stress-driven convection. The droplet then responds to an AC field with a suppressed amplitude of oscillation and the same mean deformation as that under DC forcing. Thus, low-frequency AC forcing with a suitable surfactant can plausibly be employed as a viable alternative to more energy-intensive high-frequency AC forcing.
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Affiliation(s)
- Shreyank Goel
- Department of Chemical Engineering, Indian Institute of Technology Kanpur, Uttar Pradesh 208016, India
| | - Dipin S Pillai
- Department of Chemical Engineering, Indian Institute of Technology Kanpur, Uttar Pradesh 208016, India
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6
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Cheng H, Shao W, Jin J, Wu J, Zhao M, Tang B, Zhou G. Robust reverse-electrowetting based energy harvesting on slippery surface. RSC Adv 2023; 13:31659-31666. [PMID: 37908647 PMCID: PMC10613949 DOI: 10.1039/d3ra06099c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 10/25/2023] [Indexed: 11/02/2023] Open
Abstract
Reversed-electrowetting based droplet electricity generator (REWOD-DEG) shows merits in high power densities, tunable output formats, and wide adaptability to diverse mechanical energies. However, the surface charge trapping and dielectric failure, which are also common challenges for electrowetting system, hinders the development of reliable REWOD-DEGs for long-term running. We innovatively introduce a slippery lubricant-infused porous surface (SLIPS) into REWOD-DEG. Benefits from the significant inhibitory effect for surface charge trapping and ambient contamination, self-healing characteristic given by SLIPS, and robust reversed-electrowetting based energy harvesting were achieved. The SLIPS enhanced REWOD-DEG experienced 100 days of intermittent energy harvesting without deterioration. In addition, the device shows robust performances when exposed to a variety of extreme working conditions, like low temperature, pH, humidity, fouling, and even scratching. This work may address the core application challenges of REWOD based devices, and inspire the development of other robust droplet-based electricity generators.
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Affiliation(s)
- Haimei Cheng
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University Guangzhou 510006 People's Republic of China
- National Center for International Research on Green Optoelectronics, South China Normal University Guangzhou 510006 People's Republic of China
| | - Wan Shao
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University Guangzhou 510006 People's Republic of China
- National Center for International Research on Green Optoelectronics, South China Normal University Guangzhou 510006 People's Republic of China
| | - Jing Jin
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University Guangzhou 510006 People's Republic of China
- National Center for International Research on Green Optoelectronics, South China Normal University Guangzhou 510006 People's Republic of China
| | - Junjun Wu
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University Guangzhou 510006 People's Republic of China
- National Center for International Research on Green Optoelectronics, South China Normal University Guangzhou 510006 People's Republic of China
| | - Manhong Zhao
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University Guangzhou 510006 People's Republic of China
- National Center for International Research on Green Optoelectronics, South China Normal University Guangzhou 510006 People's Republic of China
| | - Biao Tang
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University Guangzhou 510006 People's Republic of China
- National Center for International Research on Green Optoelectronics, South China Normal University Guangzhou 510006 People's Republic of China
| | - Guofu Zhou
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University Guangzhou 510006 People's Republic of China
- National Center for International Research on Green Optoelectronics, South China Normal University Guangzhou 510006 People's Republic of China
- Shenzhen Guohua Optoelectronics Tech. Co. Ltd Shenzhen 518110 People's Republic of China
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7
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Rummaneethorn P, Lee D. Dielectric charge injection (DCI)-enabled contactless droplet wetting modulation for droplet-surface material interchange. J Colloid Interface Sci 2023; 639:241-248. [PMID: 36805749 DOI: 10.1016/j.jcis.2023.02.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 01/27/2023] [Accepted: 02/02/2023] [Indexed: 02/08/2023]
Abstract
HYPOTHESIS Electrowetting-on-dielectric (EWOD) employs direct droplet-electrode contact to generate electric fields across the dielectric layer to modulate droplet wetting. Because the charged surface state drives this process, it should be possible to accomplish a contactless modulation of droplet wetting by charge injection onto the dielectric surface where a droplet is situated. EXPERIMENTS We present our technique, dielectric charge injection (DCI), to contactlessly modulate droplet wetting via corona discharge-based physics. We study the ability of droplets on nonwetting surfaces to transition to a wetting state under DCI, quantify contact angle (CA) in relation to applied voltage, and examine reversibility under regimes with and without charge injection. The observed phenomena are applied to enable droplet-surface material interchange. FINDINGS Using DCI, we induce wetting of a deionized water droplet on a non-wetting polydimethylsiloxane (PDMS) surface immersed in hexadecane, with tunable CA modulation based on applied voltage. Upon simple removal of the voltage and/or conductor, droplet fully recovers the initial non-wetting state. We combine these capabilities to enable droplet-surface material interchange of two modes: material deposition (droplet-to-surface) and material recovery (surface-to-droplet). DCI presents a unique strategy for contactless, reversible wetting state modulation that is simple yet powerful for applications such as integrating droplet microfluidics to mass spectrometry.
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Affiliation(s)
- Paradorn Rummaneethorn
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, 311A Towne Building, 220 South 33(rd) Street, Philadelphia, PA 19104, USA.
| | - Daeyeon Lee
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, 311A Towne Building, 220 South 33(rd) Street, Philadelphia, PA 19104, USA.
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8
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Tian P, Xia L, Zhu W, Wang H, Jiang D. Effects of Liquid Viscosity on the Formation and Attenuation of Capillary Waves Induced by AC Electrowetting-on-Dielectric. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:265-273. [PMID: 36534737 DOI: 10.1021/acs.langmuir.2c02480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The capillary waves induced by electrowetting-on-dielectric have great potential in terms of capillary propulsion and other applications. At present, these applications are limited by a lack of research on the effects of liquid viscosity, which is an important parameter in controlling this phenomenon. This paper examines the formation, propagation, and attenuation of electrowetting-on-dielectric-induced capillary waves (EWCWs) on a liquid-free surface with different levels of liquid viscosity. The formation and propagation of the capillary waves are visualized using a high-speed camera and a free-surface synthetic Schlieren method. A theoretical model is established to describe the wave amplitude and wave propagation of EWCWs. The results show that the liquid viscosity, as well as the surface tension, significantly affects the formation and propagation of EWCWs. Using the results presented in this paper, a new type of Stokes viscometer based on EWCWs is proposed, enabling accurate measurements of liquid viscosity over a wide range of viscosity and temperature conditions.
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Affiliation(s)
- Penghao Tian
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Dalian University of Technology, Dalian116024, China
| | - Lei Xia
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Dalian University of Technology, Dalian116024, China
| | - Wei Zhu
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Dalian University of Technology, Dalian116024, China
| | - Hongchen Wang
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Dalian University of Technology, Dalian116024, China
| | - Dongyue Jiang
- Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Dalian University of Technology, Dalian116024, China
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9
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Yu L, Yang K, Zhang Z. Galvanometer driven optical system for laser dynamic focusing. OPTICS EXPRESS 2023; 31:673-683. [PMID: 36607001 DOI: 10.1364/oe.476921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 12/13/2022] [Indexed: 06/17/2023]
Abstract
This paper proposes a novel dynamic focusing module driven by galvanometers to position the laser focus with high speed and high precision. Thanks to the extremely high repeatability and the fast response time of galvanometers, the repeatability of the laser focus positioning is far less than the Rayleigh length of the beam and its response time is around 600 µs. An important feature of the proposed module lies in that it can be further integrated to an XY galvo scanner to realize a 3-axis laser scanning system. Due to the same galvanometers of the dynamic focus module and the XY scanner, the laser focus could be positioned in a simultaneous, rapid and precise manner in all three axes. Various simulation and experimental results demonstrate the feasibility and performance of the proposed dynamic focus module and the processing capability of the 3-axis scanning system with the proposed module.
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10
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Xu W, Jin Y, Li W, Song Y, Gao S, Zhang B, Wang L, Cui M, Yan X, Wang Z. Triboelectric wetting for continuous droplet transport. SCIENCE ADVANCES 2022; 8:eade2085. [PMID: 36542697 PMCID: PMC9770939 DOI: 10.1126/sciadv.ade2085] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 11/18/2022] [Indexed: 05/28/2023]
Abstract
Manipulating liquid is of great significance in fields from life sciences to industrial applications. Owing to its advantages in manipulating liquids with high precision and flexibility, electrowetting on dielectric (EWOD) has been widely used in various applications. Despite this, its efficient operation generally needs electrode arrays and sophisticated circuit control. Here, we develop a largely unexplored triboelectric wetting (TEW) phenomenon that can directly exploit the triboelectric charges to achieve the programmed and precise water droplet control. This key feature lies in the rational design of a chemical molecular layer that can generate and store triboelectric charges through agile triboelectrification. The TEW eliminates the requirement of the electric circuit design and additional source input and allows for manipulating liquids of various compositions, volumes, and arrays on various substrates in a controllable manner. This previously unexplored wetting mechanism and control strategy will find diverse applications ranging from controllable chemical reactions to surface defogging.
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Affiliation(s)
- Wanghuai Xu
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 999077, China
- Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China
| | - Yuankai Jin
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 999077, China
| | - Wanbo Li
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 999077, China
| | - Yuxin Song
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 999077, China
| | - Shouwei Gao
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 999077, China
| | - Baoping Zhang
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 999077, China
| | - Lili Wang
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 999077, China
| | - Miaomiao Cui
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 999077, China
| | - Xiantong Yan
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 999077, China
| | - Zuankai Wang
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 999077, China
- Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China
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11
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Yang X, Wang J, Gao Z, Zhang W, Zhu H, Song Y, Wang Q, Liu M, Jiang L, Huang Y, Xia F. An orthogonal dual-regulation strategy for sensitive biosensing applications. Natl Sci Rev 2022; 9:nwac048. [PMID: 36285294 PMCID: PMC9584063 DOI: 10.1093/nsr/nwac048] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 10/22/2021] [Accepted: 02/15/2022] [Indexed: 10/27/2023] Open
Abstract
Biosensing systems based on controllable motion behaviors of droplets have attracted extensive attention, but still face challenges of insufficient sensitivity and uncontrollable dynamic range due to imprecise manipulation of droplet motion on the surfaces. Here, we report an orthogonal dual-regulation strategy for precise motion control of droplets and we demonstrate its utility as a sensitive sensing system with controllable dynamic ranges of sensing for adenosine triphosphate, miRNA, thrombin and kanamycin, as well as discrimination of five kinds of DNA. We endowed a DNA-contained bio-droplet sliding on a lubricant-infused structural surface with micro-grooves to separately adjust the resistance from liquid phase and solid phase. The resistance from liquid phase mainly depended on hydrophobic interaction between DNA and lubricant, which can be finely tuned by different DNA's average chain length. Meanwhile, the resistance from solid surface was determined by the energy barrier from the periodic micro-grooves, which can be adjusted by varying the droplet's sliding direction on the surface. The hydrophobic interaction is conformed to be orthogonal to the micro-grooves' anisotropic resistance by three different methods. This orthogonal dual-regulation strategy thus demonstrated its ability to precisely control bio-droplets' motion behaviors and sensitive detection with adjustable dynamic ranges for various bio-targets. The dual-regulation strategy will provide significant insights for super-wettable biosensors, visual inspection and beyond.
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Affiliation(s)
- Xian Yang
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074, China
- State Grid Integrated Energy Service Group CO. LTD., Beijing 100052, China
| | - Jinhua Wang
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074, China
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics, Beijing 102206, China
| | - Zhongfeng Gao
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074, China
- Shandong Provincial Key Laboratory of Detection Technology for Tumor Markers, College of Chemistry and Chemical Engineering, Linyi University, Linyi 276005, China
| | - Weiqi Zhang
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074, China
| | - Hai Zhu
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074, China
| | - Yongjun Song
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074, China
| | - Quan Wang
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074, China
| | - Mingjie Liu
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of the Ministry of Education, School of Chemistry and Environment, Beihang University, Beijing 100191, China
| | - Lei Jiang
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of the Ministry of Education, School of Chemistry and Environment, Beihang University, Beijing 100191, China
| | - Yu Huang
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074, China
- Zhejiang Institute, China University of Geosciences, Hangzhou 311305, China
| | - Fan Xia
- State Key Laboratory of Biogeology and Environmental Geology, Engineering Research Center of Nano-Geomaterials of Ministry of Education, Faculty of Material Science and Chemistry, China University of Geosciences, Wuhan 430074, China
- Zhejiang Institute, China University of Geosciences, Hangzhou 311305, China
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12
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Cheng Z, He Y, Wang Z, Jiao X, Song Y, Meng J. Controllable droplet sliding on smart shape memory slippery surface. Chem Asian J 2022; 17:e202200481. [PMID: 35768903 DOI: 10.1002/asia.202200481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 06/29/2022] [Indexed: 11/07/2022]
Abstract
Recently, slippery surfaces with controllable droplet sliding have aroused much attention in both fundamental research and realistic application. However, for almost all existing surfaces, constant stimuli such as thermal, light, magnetic fields, etc., are indispensable. Herein, by constructing pit structures on shape memory polymer and further infusing oil with low surface tension, we report a shape memory slippery surface that can overcome the above imperfection. Based on the shape memory performance, the surface can memorize diverse pit size as the surface is stretched or recovered. With the variation of pit structure, the sliding performances for both water and organic liquid droplets can be reversibly adjusted between the rolling and pinning states. This work, based on the shape memory effect, reports smart droplet sliding control through regulating surface microstructure, which not only provides a strategy for droplet sliding control, but also offers some fresh ideas for designing novel intelligent slippery surface.
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Affiliation(s)
- Zhongjun Cheng
- Harbin Institute of Technology, Natural Science Research Center, Academy of Fundamental and Interdisciplinary Sciences, Xidazhi street 92th, 150001, Harbin, CHINA
| | - Yaoxu He
- Harbin Institute of Technology, School of chemical engineering and chemistry, CHINA
| | - Zhe Wang
- Harbin Institute of Technology, School of chemical engineering and chemistry, CHINA
| | - Xiaoyu Jiao
- Shanghai Institute of Space Power-Sources, State Key Laboratory of Space Power-sources Technology, CHINA
| | - Yinbin Song
- Harbin Institute of Technology, School of chemical engineering and chemistry, CHINA
| | - Junhui Meng
- Beijing Institute of Technology, School of Aerospace Engineering, CHINA
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13
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Xiao K, Wu CX. Droplet dynamics driven by electrowetting. Phys Rev E 2022; 105:064609. [PMID: 35854554 DOI: 10.1103/physreve.105.064609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2022] [Accepted: 05/31/2022] [Indexed: 06/15/2023]
Abstract
Even though electrowetting-on-dielectric (EWOD) is a useful strategy in a wide array of biological and engineering processes with numerous droplet-manipulation applications, there is still a lack of complete theoretical interpretation on the dynamics of electrowetting. In this paper we present an effective theoretical model and use the Onsager variational principle to successfully derive general dynamic shape equations for electrowetting droplets in both the overdamped and underdamped regimes. It is found that the spreading and retraction dynamics of a droplet on EWOD substrates can be fairly well captured by our model, which agrees with previous experimental results very well in the overdamped regime. We also confirm that the transient dynamics of EW can be characterized by a timescale independent of liquid viscosity, droplet size, and applied voltage. Our model provides a complete fundamental explanation of EW-driven spreading dynamics, which is important for a wide range of applications, from self-cleaning to novel optical and digital microfluidic devices.
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Affiliation(s)
- Ke Xiao
- Department of Physics and Fujian Provincial Key Laboratory for Soft Functional Materials Research, College of Physical Science and Technology, Xiamen University, Xiamen 361005, People's Republic of China and Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou 325016, People's Republic of China
| | - Chen-Xu Wu
- Department of Physics and Fujian Provincial Key Laboratory for Soft Functional Materials Research, College of Physical Science and Technology, Xiamen University, Xiamen 361005, People's Republic of China
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14
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Liquid-Infused Porous Film Self-Assembly for Superior Light-Transmitting and Anti-Adhesion. MICROMACHINES 2022; 13:mi13040540. [PMID: 35457845 PMCID: PMC9025966 DOI: 10.3390/mi13040540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Revised: 03/24/2022] [Accepted: 03/28/2022] [Indexed: 12/10/2022]
Abstract
Liquid-Infused Surfaces (LISs), particularly known for their liquid-repelling feature, have demonstrated plenty of applications in the medical, marine, and energy fields. To improve the durability and transparency highly demanded on glass-based vision devices such as an endoscope, this study proposed a novel self-assembly method to fabricate well-ordered porous Poly-Styrene (PS)/Styrene–Butadiene–Styrene (SBS) films by simply dripping the PS/SBS dichloromethane solutions onto the glass before spinning. The effects of the solutions’ concentrations and spin speeds on the porous structure were experimentally investigated. The results showed that a certain mass ratio of PS/SBS can make the structure of the ordered porous film more regular and denser under the optimal solution concentration and spin-coating speed. Superior transparency and durability were also realized by dripping silicone oil on the porous film to build a liquid-infused surface. Applications of the as-prepared surface on devices like endoscopes, viewfinders, and goggles have been explored respectively.
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15
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Pathak S, Chakraborty M, DasGupta S. Molecular Investigation of the Actuation of Electrowetted Nanodroplets. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:3656-3665. [PMID: 35286095 DOI: 10.1021/acs.langmuir.1c03037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
It is well known that the wettability of a droplet on a solid substrate can be modified by the application of an electric field. The phenomenon of electrowetting along with the associated physics of droplet shape change and dynamics has traditionally been studied at the micro-scale leading to exciting applications. The present work is undertaken to explore the physics of electrowetting actuation of droplet movement at the molecular level. Molecular simulations are performed to obtain the dynamic spreading of the droplet under the action of a radially symmetric electric field on a silica substrate. The dynamic behavior of the contact diameter is found to be qualitatively similar to that observed at the laboratory scale. Further simulations of droplet actuation across an array of electrodes illustrated the dynamics of the center of mass, which is then used to estimate the contact line friction and compared with the predictions from a reduced-order model. A scaling analysis is used to probe the physics of the problem correlating the contact line friction coefficient and the droplet velocity after actuation. The results and understanding elicited from the fundamental approach have the potential to guide the development of quick and precise control of nano-sized droplets and may prove to be pivotal in the development of future nanofluidic systems, nanomanufacturing methodologies, and high-resolution optoelectronic devices.
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Affiliation(s)
- Shakul Pathak
- Department of Chemical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Monojit Chakraborty
- Department of Chemical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
| | - Sunando DasGupta
- Department of Chemical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
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16
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Zhao L, Seshadri S, Liang X, Bailey SJ, Haggmark M, Gordon M, Helgeson ME, Read de Alaniz J, Luzzatto-Fegiz P, Zhu Y. Depinning of Multiphase Fluid Using Light and Photo-Responsive Surfactants. ACS CENTRAL SCIENCE 2022; 8:235-245. [PMID: 35233455 PMCID: PMC8875439 DOI: 10.1021/acscentsci.1c01127] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Indexed: 05/03/2023]
Abstract
The development of noninvasive and robust strategies for manipulation of droplets and bubbles is crucial in applications such as boiling and condensation, electrocatalysis, and microfluidics. In this work, we realize the swift departure of droplets and bubbles from solid substrates by introducing photoresponsive surfactants and applying asymmetric illumination, thereby inducing a "photo-Marangoni" lift force. Experiments show that a pinned toluene droplet can depart the substrate in only 0.38 s upon illumination, and the volume of an air bubble at departure is reduced by 20%, indicating significantly faster departure. These benefits can be achieved with moderate light intensities and dilute surfactant concentrations, without specially fabricated substrates, which greatly facilitates practical applications. Simulations suggest that the net departure force includes contributions from viscous stresses directly caused by the Marangoni flow, as well as from pressure buildup due to flow stagnation at the contact line. The manipulation scheme proposed here shows potential for applications requiring droplet and bubble removal from working surfaces.
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Affiliation(s)
- Lei Zhao
- Department
of Mechanical Engineering, University of
California, Santa Barbara, Santa
Barbara, California 93106-5070, United States
| | - Serena Seshadri
- Department
of Chemistry, University of California at
Santa Barbara, Santa Barbara, California 93106-5070, United States
| | - Xichen Liang
- Department
of Chemical Engineering, University of California
at Santa Barbara, Santa Barbara, California 93106-5070, United States
| | - Sophia J. Bailey
- Department
of Chemistry, University of California at
Santa Barbara, Santa Barbara, California 93106-5070, United States
| | - Michael Haggmark
- Department
of Chemical Engineering, University of California
at Santa Barbara, Santa Barbara, California 93106-5070, United States
| | - Michael Gordon
- Department
of Chemical Engineering, University of California
at Santa Barbara, Santa Barbara, California 93106-5070, United States
| | - Matthew E. Helgeson
- Department
of Chemical Engineering, University of California
at Santa Barbara, Santa Barbara, California 93106-5070, United States
| | - Javier Read de Alaniz
- Department
of Chemistry, University of California at
Santa Barbara, Santa Barbara, California 93106-5070, United States
| | - Paolo Luzzatto-Fegiz
- Department
of Mechanical Engineering, University of
California, Santa Barbara, Santa
Barbara, California 93106-5070, United States
| | - Yangying Zhu
- Department
of Mechanical Engineering, University of
California, Santa Barbara, Santa
Barbara, California 93106-5070, United States
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17
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Determination of the Dielectrophoretic Force Induced by the Photovoltaic Effect on Lithium Niobate. MICROMACHINES 2022; 13:mi13020316. [PMID: 35208440 PMCID: PMC8875925 DOI: 10.3390/mi13020316] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 02/14/2022] [Accepted: 02/17/2022] [Indexed: 12/28/2022]
Abstract
The actuation of droplets on a surface is extremely relevant for microfluidic applications. In recent years, various methodologies have been used. A promising solution relies on iron-doped lithium niobate crystals that, when illuminated, generate an evanescent electric field in the surrounding space due to the photovoltaic effect. This field can be successfully exploited to control the motion of water droplets. Here, we present an experimental method to determine the attractive force exerted by the evanescent field. It consists of the analysis of the elongation of a pendant droplet and its detachment from the suspending syringe needle, caused by the illumination of an iron-doped lithium niobate crystal. We show that this interaction resembles that obtained by applying a voltage between the needle and a metallic substrate, and a quantitative investigation of these two types of actuation yields similar results. Pendant droplet tensiometry is then demonstrated to offer a simple solution for quickly mapping out the force at different distances from the crystal, generated by the photovoltaic effect and its temporal evolution, providing important quantitative data for the design and characterization of optofluidic devices based on lithium niobate crystals.
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18
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Li Y, Zhang Q, Chen R, Yan Y, Sun Z, Zhang X, Tian D, Jiang L. Stretch-Enhanced Anisotropic Wetting on Transparent Elastomer Film for Controlled Liquid Transport. ACS NANO 2021; 15:19981-19989. [PMID: 34841855 DOI: 10.1021/acsnano.1c07512] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Direction-controlled wetting surfaces, special for lubricating oil infused anisotropic surfaces, have attracted great research interest in directional liquid collection, expelling, transfer, and separation. Nonetheless, there are still existing difficulties in achieving directional and continuous liquid transport. Herein, we present a strategy to achieve directional liquid transport on transparent lubricating oil infused elastomer film with V-shaped prisms microarray (VPM). The results reveal that the water wetting direction in the parallel and staggered arrangement of the VPM structure surface with lubricating oil infusion is the opposite, which is completely different from the wetting direction on the usual VPM surface in air. Moreover, asymmetric stretching can enhance or weaken the directional water wetting tendency on the lubricating oil infused VPM elastomer film and even can reverse the droplet wetting direction. In a closed moist environment, tiny droplets gradually coalesce and then slip away from the lubricating oil infused VPM surface to keep the surface transparent, due to the cooperation of imbalanced Laplace pressure, resulting from the anisotropic geometric structures, varying VPMs spacing, and gravity. Thus, this work provides a paradigm to design and fabricate a type of surface engineering material in the application fields of directional expelling, liquid collection, anti-biofouling, anti-icing, drag reduction, anticorrosion, etc.
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Affiliation(s)
- Yan Li
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing 100191, P. R. China
| | - Qiuya Zhang
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing 100191, P. R. China
| | - Rui Chen
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing 100191, P. R. China
| | - Yufeng Yan
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing 100191, P. R. China
| | - Zhenning Sun
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing 100191, P. R. China
| | - Xiaofang Zhang
- School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083, P. R. China
| | - Dongliang Tian
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing 100191, P. R. China
- Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing 100191, P. R. China
| | - Lei Jiang
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing 100191, P. R. China
- Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing 100191, P. R. China
- Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100191, P. R. China
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19
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Selective control of the contact and transport between droplet pairs by electrowetting-on-dielectric for droplet-array sandwiching technology. Sci Rep 2021; 11:12355. [PMID: 34117288 PMCID: PMC8196194 DOI: 10.1038/s41598-021-91219-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 05/24/2021] [Indexed: 11/08/2022] Open
Abstract
Methodological advances in on-chip technology enable high-throughput drug screening, such as droplet-array sandwiching technology. Droplet-array sandwiching technology involves upper and lower substrates with a droplet-array designed for a one-step process. This technology is, however, limited to batch manipulation of the droplet-array. Here, we propose a method for selective control of individual droplets, which allows different conditions for individual droplet pairs. Electrowetting-on-dielectric (EWOD) technology is introduced to control the height of the droplets so that the contact between droplet-pairs can be individually controlled. Circular patterns 4 mm in diameter composed of electrodes for EWOD and hydrophilic-hydrophobic patterns for droplet formation 4 μl in volume were developed. We demonstrate the selective control of the droplet height by EWOD for an applied voltage up to 160 V and selective control of the contact and transport of substances. Presented results will provide useful method for advanced drug screening, including cell-based screening.
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20
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Frozanpoor I, Cooke MD, Ambukan V, Gallant AJ, Balocco C. Continuous Droplet-Actuating Platforms via an Electric Field Gradient: Electrowetting and Liquid Dielectrophoresis. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:6414-6422. [PMID: 34014683 PMCID: PMC8397340 DOI: 10.1021/acs.langmuir.1c00329] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
This work develops a technology for actuating droplets of any size without the requirement for high voltages or active control systems, which are typically found in competitive systems. The droplet actuation relies on two microelectrodes separated by a variable gap distance to generate an electrostatic gradient. The physical mechanism for the droplet motion is a combination of liquid dielectrophoresis and electrowetting. Investigating the system behavior as a function of the driving frequency identified the relative contribution of these two mechanisms and the optimum operating conditions. A fixed signal frequency of 0.5 kHz actuated various liquids and contaminants. Droplet actuation was demonstrated on several platforms, including linear, radial-symmetric, and bilateral-symmetric droplet motion. The electrode designs are scalable and can be fabricated on a flexible and optically transparent substrate: these key advancements will enable consumer applications that were previously inaccessible. A self-cleaning platform was also tested under laboratory conditions and on the road. This technology has significant potential in microfluidics and self-cleaning platforms, for example, in the automotive sector to clean body parts, camera covers, and sensors.
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21
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Yan W, Zhao C, Luo W, Zhang W, Li X, Liu D. Optically Guided Pyroelectric Manipulation of Water Droplet on a Superhydrophobic Surface. ACS APPLIED MATERIALS & INTERFACES 2021; 13:23181-23190. [PMID: 33945247 DOI: 10.1021/acsami.1c03407] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Controlled droplet manipulation by light has tremendous technological potential. We report here a method based on photothermally induced pyroelectric effects that enables manipulation and maneuvering of a water droplet on a superhydrophobic surface fabricated on lithium tantalite (LiTaO3). In particular, we demonstrate that the pyroelectric charge distribution has an essential role in this process. Evenly distributed charges promote a rapid hydrophobic to hydrophilic transition featuring a very large water contact angle (WCA) change of ∼76.5° in air. This process becomes fully reversible in silicone oil. In contrast, the localized charge distribution induced by guided laser illumination leads to very different and versatile functionalities, including droplet shape control and motion manipulation. The influence of a saline solution is also investigated and compared to the deionized water droplet. The focusing effect of the water droplet, a phenomenon that widely exists in nature, is particularly of interest. Simple tuning of the laser incident angle results in droplet deformation, jetting, splitting, and guided motion. Potential applications, such as droplet pinning and transfer, are presented. This approach offers a wide range of versatile functionalities and ready controllability, including contactless, electrodeless, and precise spatial and fast temporal control, with tremendous potential for applications requiring remote droplet control.
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Affiliation(s)
- Weishan Yan
- Institute of Novel Semiconductors, State Key Laboratory of Crystal Materials, Shandong University, 27 South Shanda Road, Jinan, Shandong 250100, P. R. China
| | - Chaopeng Zhao
- Institute of Novel Semiconductors, State Key Laboratory of Crystal Materials, Shandong University, 27 South Shanda Road, Jinan, Shandong 250100, P. R. China
| | - Wenyao Luo
- Institute of Novel Semiconductors, State Key Laboratory of Crystal Materials, Shandong University, 27 South Shanda Road, Jinan, Shandong 250100, P. R. China
| | - Wangyang Zhang
- Institute of Novel Semiconductors, State Key Laboratory of Crystal Materials, Shandong University, 27 South Shanda Road, Jinan, Shandong 250100, P. R. China
| | - Xi Li
- Key Laboratory of Experimental Teratology, Ministry of Education, Institute of Medical Genetics, School of Medicine, Shandong University, Jinan, Shandong 250012, P. R. China
| | - Duo Liu
- Institute of Novel Semiconductors, State Key Laboratory of Crystal Materials, Shandong University, 27 South Shanda Road, Jinan, Shandong 250100, P. R. China
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22
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Zhang BX, Wang SL, Wang YB, Yang YR, Wang XD, Yang RG. Harnessing Reversible Wetting Transition to Sweep Contaminated Superhydrophobic Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:3929-3938. [PMID: 33760619 DOI: 10.1021/acs.langmuir.1c00157] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Sweeping deposited particles is absolutely essential in order to maintain the excellent functionality of superhydrophobic surfaces. Many methods have been proposed to sweep microparticles deposited on tips of micro/nanostructures. However, how to sweep nanoparticles trapped in cavities of superhydrophobic surfaces has remained an outstanding issue. Here, we show that harnessing the reversible wetting transition provides a feasible way to sweep such nanoparticles. Using molecular dynamics simulations, we demonstrate that the electrically induced CB-W wetting transition makes liquid intrude into a groove and wet a trapped hydrophilic nanoparticle; however, once the electric field is removed, a spontaneous W-CB dewetting transition happens, and the extruded liquid transports the hydrophilic nanoparticle to the groove top, successfully picking up the trapped hydrophilic nanoparticle. We further find that the adhesion between the nanoparticle and groove bottom wall hinders the successful pickup, and picking up such a nanoparticle requires a stronger particle hydrophilicity. With the introduction of amphiphilic Janus particles into a liquid, we exhibit that the electrically induced reversible wetting transition can also successfully pick up a trapped hydrophobic nanoparticle. By means of calculations of the potential of mean force (PMF), we reveal pathways of both the CB-W wetting transition and the W-CB dewetting transition and hence answer why and how a hydrophilic or a hydrophobic nanoparticle is picked up successfully.
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Affiliation(s)
| | | | | | | | | | - Rong-Gui Yang
- School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
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23
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Aluminum doped zinc oxide deposited by atomic layer deposition and its applications to micro/nano devices. Sci Rep 2021; 11:1204. [PMID: 33441961 PMCID: PMC7806672 DOI: 10.1038/s41598-020-80880-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 12/28/2020] [Indexed: 11/26/2022] Open
Abstract
This work reports investigation on the deposition and evaluation of an aluminum-doped zinc oxide (AZO) thin film and its novel applications to micro- and nano-devices. The AZO thin film is deposited successfully by atomic layer deposition (ALD). 50 nm-thick AZO film with high uniformity is checked by scanning electron microscopy. The element composition of the deposited film with various aluminum dopant concentration is analyzed by energy-dispersive X-ray spectroscopy. In addition, a polycrystalline feature of the deposited film is confirmed by selected area electron diffraction and high-resolution transmission electron microscopy. The lowest sheet resistance of the deposited AZO film is found at 0.7 kΩ/□ with the aluminum dopant concentration at 5 at.%. A novel method employed the ALD in combination with the sacrificial silicon structures is proposed which opens the way to create the ultra-high aspect ratio AZO structures. Moreover, based on this finding, three kinds of micro- and nano-devices employing the deposited AZO thin film have been proposed and demonstrated. Firstly, nanowalled micro-hollows with an aspect ratio of 300 and a height of 15 µm are successfully produced
. Secondly, micro- and nano-fluidics, including a hollow fluidic channel with a nanowall structure as a resonator and a fluidic capillary window as an optical modulator is proposed and demonstrated. Lastly, nanomechanical resonators consisting of a bridged nanobeam structure and a vertical nanomechanical capacitive resonator are fabricated and evaluated.
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24
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Gong Z, Su Z, Liu X, Pan D, Liu J, Zheng H, Joo SW. Boosting Electrically Actuated Manipulation of Water Droplets on Lubricated Surfaces through a Corona Discharge. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:400-405. [PMID: 33356299 DOI: 10.1021/acs.langmuir.0c03048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Controllable liquid transportation is of great value in various practical applications. Here, we experimentally demonstrate a method of actuating high-speed droplet transport with large manipulation controllability on lubricated surfaces using a corona discharge generated by a simple needle-plate electrode configuration. Linear motion of droplets is realized with a maximum velocity of 30 mm/s. Factors affecting the velocity of these droplets are analyzed systematically, and the mechanism of droplet transport is explained. The lubrication film flow induced by charge deposition is shown to be the dominating factor in the droplet manipulation controllability. The new method presented here opens a new path of high-performance manipulation of liquid droplets by controlling the lubrication liquid film flow with charge deposition.
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Affiliation(s)
- Zheng Gong
- School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China
| | - Zhenpeng Su
- The Institute of Technological Sciences, Wuhan University, Wuhan 430072, China
| | - Xiaofeng Liu
- School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China
| | - Di Pan
- School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China
| | - Jie Liu
- School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China
| | - Huai Zheng
- School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China
- The Institute of Technological Sciences, Wuhan University, Wuhan 430072, China
| | - Sang Woo Joo
- School of Mechanical Engineering, Yeungnam University, Gyeongsan 712-749, South Korea
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25
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Wang C, Guo Z. A comparison between superhydrophobic surfaces (SHS) and slippery liquid-infused porous surfaces (SLIPS) in application. NANOSCALE 2020; 12:22398-22424. [PMID: 33174577 DOI: 10.1039/d0nr06009g] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Slippery liquid-infused porous surfaces inspired by the Nepenthes pitcher plant exhibit excellent performances and are known for their extremely low contact angle hysteresis (<5°) and smooth surface. In contrast, superhydrophobic surfaces (SHS) exhibit poor pressure stability, difficulty in self-healing, and difficulty in removing low surface tension liquids or organic solvents, which can affect the stable air layer. Thus, these issues can be avoided through the replacement of SHS with slippery liquid infused porous surfaces (SLIPS). In this review, the theoretical models of SHS and SLIPS are classified initially, and several design standards for the preparation of SLIPS are briefly described. Then, we focus on comparing the differences in the application of SHS and SLIPS, such as pressure stability, transparency, and droplet manipulation. However, there are still some problems that need to be improved during the preparation of SLIPS, such as the evaporation of the lubricant layer, the use of a lubricant layer of toxic perfluoropolyether and other substances, and easily lost nanostructured lubricant layer. Accordingly, several new improved methods are proposed in this review, and finally, the potential applications and development prospects of SLIPS are presented.
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Affiliation(s)
- Chenghong Wang
- Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei University, Wuhan 430062, P. R. China.
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26
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Armstrong S, McHale G, Ledesma-Aguilar R, Wells GG. Evaporation and Electrowetting of Sessile Droplets on Slippery Liquid-Like Surfaces and Slippery Liquid-Infused Porous Surfaces (SLIPS). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:11332-11340. [PMID: 32882130 PMCID: PMC8011908 DOI: 10.1021/acs.langmuir.0c02020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Sessile droplet evaporation underpins a wide range of applications from inkjet printing to coating. However, drying times can be variable and contact-line pinning often leads to undesirable effects, such as ring stain formation. Here, we show voltage programmable control of contact angles during evaporation on two pinning-free surfaces. We use an electrowetting-on-dielectric approach and Slippery Liquid-Infused Porous (SLIP) and Slippery Omniphobic Covalently Attached Liquid-Like (SOCAL) surfaces to achieve a constant contact angle mode of evaporation. We report evaporation sequences and droplet lifetimes across a broad range of contact angles from 105°-67°. The values of the contact angles during evaporation are consistent with expectations from electrowetting and the Young-Lippman equation. The droplet contact areas reduce linearly in time, and this provides estimates of diffusion coefficients close to the expected literature value. We further find that the total time of evaporation over the broad contact angle range studied is only weakly dependent on the value of the contact angle. We conclude that on these types of slippery surfaces, droplet lifetimes can be predicted and controlled by the droplet's volume and physical properties (density, diffusion coefficient, and vapor concentration difference to the vapor phase) largely independent of the precise value of contact angle. These results are relevant to applications, such as printing, spraying, coating, and other processes, where controlling droplet evaporation and drying is important.
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Affiliation(s)
- S. Armstrong
- Smart
Materials & Surfaces Laboratory, Faculty of Engineering &
Environment, Northumbria University, Newcastle upon Tyne, NE1
8ST, U.K.
- School
of Engineering, University of Edinburgh, Sanderson Building, Edinburgh, EH9 3FB, U.K.
| | - G. McHale
- Smart
Materials & Surfaces Laboratory, Faculty of Engineering &
Environment, Northumbria University, Newcastle upon Tyne, NE1
8ST, U.K.
- School
of Engineering, University of Edinburgh, Sanderson Building, Edinburgh, EH9 3FB, U.K.
| | - R. Ledesma-Aguilar
- Smart
Materials & Surfaces Laboratory, Faculty of Engineering &
Environment, Northumbria University, Newcastle upon Tyne, NE1
8ST, U.K.
- School
of Engineering, University of Edinburgh, Sanderson Building, Edinburgh, EH9 3FB, U.K.
| | - G. G. Wells
- Smart
Materials & Surfaces Laboratory, Faculty of Engineering &
Environment, Northumbria University, Newcastle upon Tyne, NE1
8ST, U.K.
- School
of Engineering, University of Edinburgh, Sanderson Building, Edinburgh, EH9 3FB, U.K.
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27
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Tang B, Meng C, Zhuang L, Groenewold J, Qian Y, Sun Z, Liu X, Gao J, Zhou G. Field-Induced Wettability Gradients for No-Loss Transport of Oil Droplets on Slippery Surfaces. ACS APPLIED MATERIALS & INTERFACES 2020; 12:38723-38729. [PMID: 32846489 DOI: 10.1021/acsami.0c06389] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Transporting oil droplets is crucial for a wide range of industrial and biomedical applications but remains highly challenging due to the large contact angle hysteresis on most solid surfaces. A liquid-infused slippery surface has a low hysteresis contact angle and is a highly promising platform if sufficient wettability gradient can be created. Current strategies used to create wettability gradient typically rely on the engineering of the chemical composition or geometrical structure. However, these strategies are inefficient on a slippery surface because the infused liquid tends to conceal the gradient in the chemical composition and small-scale geometrical structure. Magnifying the structure, on the other hand, will significantly distort the surface topography, which is unwanted in practice. In this study, we address this challenge by introducing a field-induced wettability gradient on a flat slippery surface. By printing radial electrodes array, we can pattern the electric field, which induces gradient contact angles. Theoretical analysis and experimental results reveal that the droplet transport behavior can be captured by a nondimensional electric Bond number. Our surface enables no-loss transport of various types of droplets, which we expect to find important applications such as heat transfer, anticontamination, microfluidics, and biochemical analysis.
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Affiliation(s)
- Biao Tang
- National Center for International Research on Green Optoelectronics, Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Chuanzhi Meng
- National Center for International Research on Green Optoelectronics, Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Lei Zhuang
- National Center for International Research on Green Optoelectronics, Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Jan Groenewold
- National Center for International Research on Green Optoelectronics, Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
- Van't Hoff Laboratory for Physical and Colloid Chemistry, Debye Research Institute, Utrecht University, Padualaan 8, Utrecht 3584 CH, The Netherlands
| | - Yuyang Qian
- National Center for International Research on Green Optoelectronics, Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Zhongqian Sun
- National Center for International Research on Green Optoelectronics, Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
| | - Xueli Liu
- Faculty of Science and Technology, University of Twente, Enschede 7500 AE, The Netherlands
| | - Jun Gao
- Faculty of Science and Technology, University of Twente, Enschede 7500 AE, The Netherlands
| | - Guofu Zhou
- National Center for International Research on Green Optoelectronics, Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, P. R. China
- Shenzhen Guohua Optoelectronics Tech. Co. Ltd., Academy of Shenzhen Guohua, Optoelectronics, Shenzhen 518110, P. R. China
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Wang M, Zhou L, Hou Y, He W, Liu W, Wu F, Hou X. Dynamic and reversible electrowetting with low voltage on the dimethicone infused carbon nanotube array in air. CHINESE CHEM LETT 2020. [DOI: 10.1016/j.cclet.2020.04.059] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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29
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Li H, Shkolyar E, Wang J, Conti S, Pao AC, Liao JC, Wong TS, Wong PK. SLIPS-LAB-A bioinspired bioanalysis system for metabolic evaluation of urinary stone disease. SCIENCE ADVANCES 2020; 6:eaba8535. [PMID: 32494753 PMCID: PMC7244315 DOI: 10.1126/sciadv.aba8535] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 03/18/2020] [Indexed: 05/21/2023]
Abstract
Urinary stone disease is among the most common medical conditions. Standard evaluation of urinary stone disease involves a metabolic workup of stone formers based on measurement of minerals and solutes excreted in 24-hour urine samples. Nevertheless, 24-hour urine testing is slow, expensive, and inconvenient for patients, which has hindered widespread adoption in clinical practice. Here, we demonstrate SLIPS-LAB (Slippery Liquid-Infused Porous Surface Laboratory), a droplet-based bioanalysis system, for rapid measurement of urinary stone-associated analytes. The ultra-repellent and antifouling properties of SLIPS, which is a biologically inspired surface technology, allow autonomous liquid handling and manipulation of physiological samples without complicated sample preparation procedures and supporting equipment. We pilot a study that examines key urinary analytes in clinical samples from patients with urinary stone. The simplicity and speed of SLIPS-LAB hold the potential to provide actionable diagnostic information for patients with urinary stone disease and rapid feedback for responses to dietary and pharmacologic treatments.
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Affiliation(s)
- Hui Li
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA, USA
| | - Eugene Shkolyar
- Department of Urology, Stanford University School of Medicine, Stanford, CA, USA
| | - Jing Wang
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, PA, USA
- Materials Research Institute, The Pennsylvania State University, University Park, PA, USA
| | - Simon Conti
- Department of Urology, Stanford University School of Medicine, Stanford, CA, USA
- Veterans Affairs Palo Alto Health Care System, Palo Alto, CA, USA
| | - Alan C. Pao
- Veterans Affairs Palo Alto Health Care System, Palo Alto, CA, USA
- Division of Nephrology, Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Joseph C. Liao
- Department of Urology, Stanford University School of Medicine, Stanford, CA, USA
- Veterans Affairs Palo Alto Health Care System, Palo Alto, CA, USA
| | - Tak-Sing Wong
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA, USA
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, PA, USA
- Materials Research Institute, The Pennsylvania State University, University Park, PA, USA
| | - Pak Kin Wong
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA, USA
- Department of Mechanical Engineering, The Pennsylvania State University, University Park, PA, USA
- Department of Surgery, The Pennsylvania State University, College of Medicine, Hershey, PA, USA
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30
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Wang J, Zhang J, Pei X, Liu S, Ning F, Li Y, Wang C. Synergistic effects of the tip effect and electric adsorption on the enhanced electrowetting-on-dielectric performance of structured ZnO surfaces. CrystEngComm 2020. [DOI: 10.1039/d0ce00047g] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
To improve the spreading ability of water droplet on structured surface, the tip effect is proposed to enhance the local electric field near the cone tip under the voltage application, and further increases the horizontal force on the water droplet.
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Affiliation(s)
- Jian Wang
- Key Laboratory of Atomic and Molecular Physics & Functional Materials of Gansu Province
- College of Physics and Electronic Engineering
- Northwest Normal University
- Lanzhou
- China
| | - Jianwen Zhang
- Key Laboratory of Atomic and Molecular Physics & Functional Materials of Gansu Province
- College of Physics and Electronic Engineering
- Northwest Normal University
- Lanzhou
- China
| | - Xinyu Pei
- Key Laboratory of Atomic and Molecular Physics & Functional Materials of Gansu Province
- College of Physics and Electronic Engineering
- Northwest Normal University
- Lanzhou
- China
| | - Shu Liu
- Key Laboratory of Atomic and Molecular Physics & Functional Materials of Gansu Province
- College of Physics and Electronic Engineering
- Northwest Normal University
- Lanzhou
- China
| | - Fei Ning
- Key Laboratory of Atomic and Molecular Physics & Functional Materials of Gansu Province
- College of Physics and Electronic Engineering
- Northwest Normal University
- Lanzhou
- China
| | - Yan Li
- Key Laboratory of Atomic and Molecular Physics & Functional Materials of Gansu Province
- College of Physics and Electronic Engineering
- Northwest Normal University
- Lanzhou
- China
| | - Chengwei Wang
- Key Laboratory of Atomic and Molecular Physics & Functional Materials of Gansu Province
- College of Physics and Electronic Engineering
- Northwest Normal University
- Lanzhou
- China
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31
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Dey R, van Gorcum M, Mugele F, Snoeijer JH. Soft electrowetting. SOFT MATTER 2019; 15:6469-6475. [PMID: 31289803 DOI: 10.1039/c9sm00847k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Electrowetting is a commonly used tool to manipulate sessile drops on hydrophobic surfaces. By applying an external voltage over a liquid and a dielectric-coated surface, one achieves a reduction of the macroscopic contact angles for increasing voltage. The electrostatic forces all play out near the contact line, on a scale of the order of the thickness of the solid dielectric layer. Here we explore the case where the dielectric is a soft elastic layer, which deforms elastically under the effect of electrostatic and capillary forces. The wetting behaviour is quantified by measurements of the static and dynamic contact angles, complemented by confocal microscopy to reveal the elastic deformations. Even though the mechanics near the contact line is highly intricate, the macroscopic contact angles can be understood from global conservation laws in the spirit of Young-Lippmann. The key finding is that, while elasticity has no effect on the static electrowetting angle, the substrate's viscoelasticity completely dictates the spreading dynamics of electrowetting.
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Affiliation(s)
- Ranabir Dey
- Max Planck Institute for Dynamics and Self-Organization, Am Fassberg 17, 37077 Goettingen, Germany. and Physics of Complex Fluids Group, Faculty of Science and Technology, University of Twente, P. O. Box 217, 7500AE Enschede, The Netherlands
| | - Mathijs van Gorcum
- Physics of Fluids Group, Faculty of Science and Technology, University of Twente, P. O. Box 217, 7500AE Enschede, The Netherlands.
| | - Frieder Mugele
- Physics of Complex Fluids Group, Faculty of Science and Technology, University of Twente, P. O. Box 217, 7500AE Enschede, The Netherlands
| | - Jacco H Snoeijer
- Physics of Fluids Group, Faculty of Science and Technology, University of Twente, P. O. Box 217, 7500AE Enschede, The Netherlands.
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32
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Villegas M, Zhang Y, Abu Jarad N, Soleymani L, Didar TF. Liquid-Infused Surfaces: A Review of Theory, Design, and Applications. ACS NANO 2019; 13:8517-8536. [PMID: 31373794 DOI: 10.1021/acsnano.9b04129] [Citation(s) in RCA: 139] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Due to inspiration from the Nepenthes pitcher plant, a frontier of devices has emerged with unmatched capabilities. Liquid-infused surfaces (LISs), particularly known for their liquid-repelling behavior under low tilting angles (<5°), have demonstrated a plethora of applications in medical, marine, energy, industrial, and environmental materials. This review presents recent developments of LIS technology and its prospective to define the future direction of this technology in solving tomorrow's real-life challenges. First, an introduction to the different models explaining the physical phenomena of these surfaces, their wettability, and viscous-dependent frictional forces is discussed. Then, an outline of different emerging strategies required to fabricate a stable liquid-infused interface is presented, including different substrates, lubricants, surface chemistries, and design parameters which can be tuned depending on the application. Furthermore, applications of LIS coatings in the areas of anticorrosion, antifouling, anti-icing, self-healing, droplet manipulation, and biomedical devices will be presented followed by the limitations and future direction of this technology.
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33
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He X, Zhang J, Zhang X, Deng Y. Droplet manipulation with polarity-dependent low-voltage electrowetting on an open slippery liquid infused porous surface. SOFT MATTER 2019; 15:5211-5219. [PMID: 31149699 DOI: 10.1039/c9sm00812h] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
This paper reports an open-loop method for highly efficient and precise droplet manipulation with polarity-dependent low-voltage electrowetting on a perfluorinated silane modified slippery liquid infused porous surface (SLIPS) in which a droplet can be driven between individual square electrodes. The electrowetting phenomenon on modified SLIPS was investigated first, and it exhibited an up to 55° contact angle difference with respect to voltage polarity while the threshold voltage was reduced to only 2 V. Then, a coplanar electrode experiment was designed to study the performance of droplet manipulation on several modified SLIPS samples with different vertically placed times and silicon oil viscosities. The optimal condition for preparing a modified SLIPS membrane is that a sample is placed vertically for 2 hours after infusing 10 cSt silicon oil, on which the droplet can be driven with the fastest velocity, and the activation voltage for moving a droplet is only 8 V. Finally, multi-droplet simultaneous and continuous manipulation on modified SLIPS in bi-direction on a loop of square electrodes was achieved. Interestingly, unlike asymmetric electrowetting, actuation methods on a solid insulator and hydrophobic layers, the droplet actuation velocity was not limited by the contact angle saturation effect and always increased with the applied voltage on modified SLIPS. This method achieves a very wide range of droplet continuous manipulation velocities from 0.075 mm s-1 to 123 mm s-1 under 20 V to 500 V applied voltage and the continuous droplet actuation voltage exhibits at least a 15-fold decrease compared to that of an unmodified SLIPS membrane.
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Affiliation(s)
- Xiaodong He
- School of Information Science and Engineering, Lanzhou University, No. 222 Tianshui South Road, Lanzhou 730000, China.
| | - Jianfeng Zhang
- School of Information Science and Engineering, Lanzhou University, No. 222 Tianshui South Road, Lanzhou 730000, China.
| | - Xiaoping Zhang
- School of Information Science and Engineering, Lanzhou University, No. 222 Tianshui South Road, Lanzhou 730000, China.
| | - Youquan Deng
- Centre for Green Chemistry and Catalysis, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, No. 18 Tianshui Middle Road, Lanzhou, 730000, China.
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34
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Geng H, Cho SK. Antifouling digital microfluidics using lubricant infused porous film. LAB ON A CHIP 2019; 19:2275-2283. [PMID: 31184676 DOI: 10.1039/c9lc00289h] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Electrowetting-driven digital (droplet-based) microfluidics has a tremendous impact on lab-on-a-chip applications. However, the biofouling problem impedes the real applications of such digital microfluidics. Here we report antifouling digital microfluidics by introducing lubricant infused porous film to electrowetting (more exactly, electrowetting on dielectric or EWOD). Such film minimizes direct contact between droplets and the solid surface but provides liquid-liquid contact between droplets and the lubricant liquid, which thus prevents unspecific adsorption of biomolecules to the solid surface. We demonstrate the compatibility of the lubricant infused film with EWOD to transport bio droplets. This configuration shows robust and high performance even for long cyclic operations without fouling in a wide range of concentrations of protein solutions. In addition, a variety of conductive droplets, including deionized (DI) water, saline, protein solution, DNA solution, sheep blood, milk, ionic liquid and honey, are examined, similarly showing high performance in cyclic transportations. In addition, using the same electrode patterns used in EWOD, transportations of dielectric (non-conductive) droplets including light crude oil, propylene carbonate and alcohol are also achieved. Such capability of droplet handling without fouling will certainly benefit the practical applications of digital microfluidics in droplet handling, sampling, reaction, diagnosis in clinic medicine, biotechnology and chemistry fields.
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Affiliation(s)
- Hongyao Geng
- Department of Mechanical Engineering and Materials Science, University of Pittsburgh, PA 15261, USA.
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35
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Ashrafi Z, Lucia L, Krause W. Nature-Inspired Liquid Infused Systems for Superwettable Surface Energies. ACS APPLIED MATERIALS & INTERFACES 2019; 11:21275-21293. [PMID: 31120721 DOI: 10.1021/acsami.9b00930] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The development of an innovative interfacial wetting strategy known as liquid infused systems offers great promise for the advanced design of superwetting and superantiwetting substrates to overcome the drawbacks of textured surfaces classified under the heading of Cassie/Wenzel states. The potential value of nature-inspired surfaces has significant potential to address scientific and technological challenges within the field of interfacial chemistry. The objective of the current review is to provide insights into a fruitful and young field of research, highlight its historical developments, examine its nature-inspired design principles, gauge recent progress in emerging applications, and offer a fresh perspective for future research.
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Affiliation(s)
- Zahra Ashrafi
- Fiber and Polymer Science , North Carolina State University , Campus Box 7616, Raleigh , North Carolina 27695 , United States
| | - Lucian Lucia
- Fiber and Polymer Science , North Carolina State University , Campus Box 7616, Raleigh , North Carolina 27695 , United States
- Department of Forest Biomaterial , North Carolina State University , Campus Box 8005, Raleigh , North Carolina 27695 , United States
- Department of Chemistry , North Carolina State University , Campus Box 8204, Raleigh , North Carolina 27695 , United States
- State Key Laboratory of Bio-based Materials & Green Papermaking , Qilu University of Technology/Shandong Academy of Sciences , Jinan , PR China 250353
| | - Wendy Krause
- Fiber and Polymer Science , North Carolina State University , Campus Box 7616, Raleigh , North Carolina 27695 , United States
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36
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McHale G, Orme BV, Wells GG, Ledesma-Aguilar R. Apparent Contact Angles on Lubricant-Impregnated Surfaces/SLIPS: From Superhydrophobicity to Electrowetting. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:4197-4204. [PMID: 30759342 DOI: 10.1021/acs.langmuir.8b04136] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
A fundamental limitation of liquids on many surfaces is their contact line pinning. This limitation can be overcome by infusing a nonvolatile and immiscible liquid or lubricant into the texture or roughness created in or applied onto the solid substrate so that the liquid of interest no longer directly contacts the underlying surface. Such slippery liquid-infused porous surfaces (SLIPS), also known as lubricant-impregnated surfaces, completely remove contact line pinning and contact angle hysteresis. However, although a sessile droplet may rest on such a surface, its contact angle can be only an apparent contact angle because its contact is now with a second liquid and not a solid. Close to the solid, the droplet has a wetting ridge with a force balance of the liquid-liquid and liquid-vapor interfacial tensions described by Neumann's triangle rather than Young's law. Here, we show how, provided the lubricant coating is thin and the wetting ridge is small, a surface free energy approach can be used to obtain an apparent contact angle equation analogous to Young's law using interfacial tensions for the lubricant-vapor and liquid-lubricant and an effective interfacial tension for the combined liquid-lubricant-vapor interfaces. This effective interfacial tension is the sum of the liquid-lubricant and the lubricant-vapor interfacial tensions or the liquid-vapor interfacial tension for a positive and negative spreading power of the lubricant on the liquid, respectively. Using this approach, we then show how Cassie-Baxter, Wenzel, hemiwicking, and other equations for rough, textured or complex geometry surfaces and for electrowetting and dielectrowetting can be used with the Young's law contact angle replaced by the apparent contact angle from the equivalent smooth lubricant-impregnated surface. The resulting equations are consistent with the literature data. These results enable equilibrium contact angle theory for sessile droplets on surfaces to be used widely for surfaces that retain a thin and conformal SLIPS coating.
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Affiliation(s)
- Glen McHale
- Smart Materials & Surfaces Laboratory, Faculty of Engineering & Environment , Northumbria University , Newcastle upon Tyne NE1 8ST , U.K
| | - Bethany V Orme
- Smart Materials & Surfaces Laboratory, Faculty of Engineering & Environment , Northumbria University , Newcastle upon Tyne NE1 8ST , U.K
| | - Gary G Wells
- Smart Materials & Surfaces Laboratory, Faculty of Engineering & Environment , Northumbria University , Newcastle upon Tyne NE1 8ST , U.K
| | - Rodrigo Ledesma-Aguilar
- Smart Materials & Surfaces Laboratory, Faculty of Engineering & Environment , Northumbria University , Newcastle upon Tyne NE1 8ST , U.K
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37
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Xu W, Zhou X, Hao C, Zheng H, Liu Y, Yan X, Yang Z, Leung M, Zeng XC, Xu RX, Wang Z. SLIPS-TENG: robust triboelectric nanogenerator with optical and charge transparency using a slippery interface. Natl Sci Rev 2019; 6:540-550. [PMID: 34691903 PMCID: PMC8291521 DOI: 10.1093/nsr/nwz025] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Revised: 02/13/2019] [Accepted: 02/14/2019] [Indexed: 11/14/2022] Open
Abstract
Abstract
Energy harvesting devices that prosper in harsh environments are highly demanded in a wide range of applications ranging from wearable and biomedical devices to self-powered and intelligent systems. Particularly, over the past several years, the innovation of triboelectric nanogenerators (TENGs) that efficiently convert ambient kinetic energy of water droplets or wave power to electricity has received growing attention. One of the main bottlenecks for the practical implications of such devices originates from the fast degradation of the physiochemical properties of interfacial materials under harsh environments. To overcome these challenges, here we report the design of a novel slippery lubricant-impregnated porous surface (SLIPS) based TENG, referred to as SLIPS-TENG, which exhibits many distinctive advantages over conventional design including optical transparency, configurability, self-cleaning, flexibility, and power generation stability, in a wide range of working environments. Unexpectedly, the slippery and configurable lubricant layer not only serves as a unique substrate for liquid/droplet transport and optical transmission, but also for efficient charge transfer. Moreover, we show that there exists a critical thickness in the liquid layer, below which the triboelectric effect is almost identical to that without the presence of such a liquid film. Such an intriguing charge transparency behavior is reminiscent of the wetting transparency and van der Waals potential transparency of graphene previously reported, though the fundamental mechanism remains to be elucidated. We envision that the marriage of these two seemingly totally different arenas (SLIPS and TENG) provides a paradigm shift in the design of robust and versatile energy devices that can be used as a clean and longer-lifetime alternative in various working environments.
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Affiliation(s)
- Wanghuai Xu
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China
- Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230026, China
| | - Xiaofeng Zhou
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China
- Shanghai Key Laboratory of Multidimensional Information Processing, Department of Electronic Engineering, East China Normal University, Shanghai 200241, China
| | - Chonglei Hao
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China
| | - Huanxi Zheng
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China
| | - Yuan Liu
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - Xiantong Yan
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China
| | - Zhengbao Yang
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China
| | - Michael Leung
- School of Energy and Environment, City University of Hong Kong, Hong Kong, China
| | - Xiao Cheng Zeng
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
| | - Ronald X Xu
- Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230026, China
| | - Zuankai Wang
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China
- Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong, China
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38
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Li J, Song Y, Zheng H, Feng S, Xu W, Wang Z. Designing biomimetic liquid diodes. SOFT MATTER 2019; 15:1902-1915. [PMID: 30758033 DOI: 10.1039/c9sm00072k] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Just as the innovation of electronic diodes that allow the current to flow in one direction provides a foundation for the development of digital technologies, the engineering of surfaces or devices that allow the directional and spontaneous transport of fluids, termed liquid diodes, is highly desired in a wide spectrum of applications ranging from medical microfluidics, advanced printing, heat management and water collection to oil-water separation. Recent advances in manufacturing, visualization techniques, and biomimetics have led to exciting progress in the design of various liquid diodes. In spite of exciting progress, formulating a general framework broad enough to guide the design, optimization and fabrication of engineered liquid diodes remains a challenging task to date. In this review, we first present an overview of the development of biological and engineered liquid diodes to elucidate how to control the surface chemistry and topography to regulate the transport of liquids without the need for external energy. Then the latest design strategies allowing for the creation of longitudinal and transverse liquid diodes are discussed and compared. We also define some figures of merit such as the rectification coefficient and the transport velocity and distance to quantify the performance of liquid diodes. Finally, we highlight perspectives on the development of engineered liquid diodes that transcend nature and adapt to various practical applications.
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Affiliation(s)
- Jiaqian Li
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong 999077, China
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Self-Healing Flexible Conductive Film by Repairing Defects via Flowable Liquid Metal Droplets. MICROMACHINES 2019; 10:mi10020113. [PMID: 30754642 PMCID: PMC6412573 DOI: 10.3390/mi10020113] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 01/18/2019] [Accepted: 02/01/2019] [Indexed: 11/30/2022]
Abstract
Self-healing flexible conductive films have been fabricated, evaluated, and applied. The film is composed of a fragile indium tin oxide (ITO) layer covered with sprayed liquid metal (LM) droplets. Self-healing of electrical conductivity is achieved via spontaneous capillary wicking of LM droplets into cracks/defects of the ITO film. The liquid metal adhering onto the ITO layer can also connect the ITO fragments during bending to keep the overall conductivity of the composite LM/ITO film stable. Stable and reversible electrowetting performance has been achieved with the composite LM/ITO as the conductive film, in either flat or curved states.
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40
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Bormashenko E. Physics of pre-wetted, lubricated and impregnated surfaces: a review. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2019; 377:20180264. [PMID: 30967071 DOI: 10.1098/rsta.2018.0264] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 09/14/2018] [Indexed: 06/09/2023]
Abstract
Wetting phenomena occurring on pre-wetted flat and rough solid surfaces are reviewed. The wetting of lubricated flat surfaces is strongly correlated with the tribological properties of a solid/lubricant pair. The phenomena taking place on micro- and nano-rough oil-impregnated surfaces have attracted the attention of the scientific community due to their numerous promising applications as omniphobic, self-healing, anti-icing and anti-bacterial interfaces. On the other hand, these phenomena are rich in their physical content. The effects observed on natural and artificial, bioinspired oil-impregnated surfaces are discussed, including electrowetting of oil-impregnated surfaces, enabling low-voltage reversible control of the droplet shape. This article is part of the theme issue 'Bioinspired materials and surfaces for green science and technology'.
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Affiliation(s)
- Edward Bormashenko
- Engineering Faculty, Chemical Engineering, Biotechnology and Materials Department, Ariel University , PO Box 3, 407000 Ariel , Israel
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41
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Han K, Heng L, Zhang Y, Liu Y, Jiang L. Slippery Surface Based on Photoelectric Responsive Nanoporous Composites with Optimal Wettability Region for Droplets' Multifunctional Manipulation. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2019; 6:1801231. [PMID: 30643721 PMCID: PMC6325596 DOI: 10.1002/advs.201801231] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Revised: 09/27/2018] [Indexed: 05/18/2023]
Abstract
The development of responsive slippery surfaces is important because of the high demand for such materials in the fields of liquid manipulation on biochips, microfluidics, microreactions, and liquid-harvesting devices. Although great progress has been achieved, the effect of substrate wettability on slippery surfaces stability is overlooked by scientists. In addition, current responsive slippery surfaces generally function utilizing single external stimuli just for imprecisely controlling liquid motion, while advanced intelligences are always expected to be integrated into one smart interface material for widespread multifunctional applications. Therefore, designing slippery surfaces that collaboratively respond to complex external stimuli and possess sophisticated composite function for expanding applications from controlling droplets motion to patterned writing is urgently needed but remains a challenge. Here, a photoelectric cooperative-responsive slippery surface based on ZnO nanoporous composites is demonstrated. First, the effect of composite surface wettability on slippery surface stability is systematically researched and the optimum wettability region for fabricating stable slippery surfaces is determined. Furthermore, controllable droplet motion and patterned writing are realized on the same slippery surfaces under photoelectric cooperative stimuli, and the related response mechanism is also deeply studied. This kind of material has potential applications in biochips, microfluidics, in situ patterning, and water-harvesting systems.
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Affiliation(s)
- Keyu Han
- Key Laboratory of Bio‐Inspired Smart Interfacial Science and Technology of Ministry of EducationBeijing Key Laboratory of Bio‐inspired Energy Materials and DevicesSchool of ChemistryBeihang UniversityBeijing100191China
| | - Liping Heng
- Key Laboratory of Bio‐Inspired Smart Interfacial Science and Technology of Ministry of EducationBeijing Key Laboratory of Bio‐inspired Energy Materials and DevicesSchool of ChemistryBeihang UniversityBeijing100191China
| | - Yuqi Zhang
- College of Chemistry and Chemical EngineeringYan'an UniversityYan'anShaanxi716000P. R. China
| | - Yao Liu
- College of Chemistry and Chemical EngineeringYan'an UniversityYan'anShaanxi716000P. R. China
| | - Lei Jiang
- Key Laboratory of Bio‐Inspired Smart Interfacial Science and Technology of Ministry of EducationBeijing Key Laboratory of Bio‐inspired Energy Materials and DevicesSchool of ChemistryBeihang UniversityBeijing100191China
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42
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Guo Y, Deng Y, Xu B, Henzen A, Hayes R, Tang B, Zhou G. Asymmetrical Electrowetting on Dielectrics Induced by Charge Transfer through an Oil/Water Interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:11943-11951. [PMID: 30204450 DOI: 10.1021/acs.langmuir.8b01718] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Electrowetting on dielectrics is a fascinating as well as a precise way in microfluid manipulation. As one of the controversial conclusions, charge trapping on the dielectric surface might be one of the causes which induces water contact angle saturation and forms one of the significant issues that bear on the applications of electrowetting on dielectrics. Recently, it was demonstrated that the contact angle saturation can be significantly reduced by employing an oil lubrication layer on the hydrophobic surface. In this work, we have investigated the influence of effects of an oil layer on the electrowetting behavior by dissolving a nonpolar oil-soluble dye in the oil phase. We monitored the contact angle of water drops with varying pH on an oil-lubricated hydrophobic insulator. Interestingly, we found asymmetry in the electrowetting curve. Several analysis methods were proceeded trying to explain this asymmetric electrowetting phenomenon. First and foremost, the electrochemical properties of dye were investigated by cyclic voltammetry which demonstrates that oxidation-reduction reactions of the dye can indeed happen on the electrode and one irreversible peak was found which indicated that the dye molecule might decompose at a higher voltage. Second, thin-layer cyclic voltammetry confirmed ions can transgress the oil/water interface. Also, the conductivity of the oil phase increases with the dissolved dye concentration, which indicates that charges can be transported in the oil phase. Finally, to further understand the transfer mechanism, the transient current of dye-doped oil was measured, which indicates that the formation of inverse micelles in the oil phase at high voltage could be one of the charge carriers. We demonstrated the oil-property-dependent asymmetry phenomenon of electrowetting and its association with charge transfer through the oil/water interface for the first time.
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Affiliation(s)
| | - Yong Deng
- Shenzhen Guohua Optoelectronics Tech. Co. Ltd. , Shenzhen 518110 , P. R. China
- Academy of Shenzhen Guohua Optoelectronics , Shenzhen 518110 , P. R. China
| | - Bojian Xu
- Shenzhen Guohua Optoelectronics Tech. Co. Ltd. , Shenzhen 518110 , P. R. China
- Academy of Shenzhen Guohua Optoelectronics , Shenzhen 518110 , P. R. China
| | | | | | | | - Guofu Zhou
- Shenzhen Guohua Optoelectronics Tech. Co. Ltd. , Shenzhen 518110 , P. R. China
- Academy of Shenzhen Guohua Optoelectronics , Shenzhen 518110 , P. R. China
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43
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Subramanian SG, Chakraborty M, Tenneti S, DasGupta S. Electrodewetting and Wetting of an Extended Meniscus. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:9897-9906. [PMID: 30052450 DOI: 10.1021/acs.langmuir.8b00967] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Here, we report the intriguing movements of an extended liquid meniscus on a silicon substrate under the influence of sinusoidal alternating current (AC) voltages at different operating frequencies. As opposed to droplet electrowetting, wherein the droplet spreads and experiences oscillations at the free surface, the application of AC voltage to a thin liquid film results in distinct and uniform dewetting, in conjunction with augmented wetting. Image analyzing interferometry is used for the precise measurement of the film thickness profile and other associated parameters. We postulate that the classic Young-Lippmann equation fails to explain the dynamics of an extended meniscus and evince that the dynamics of film displacement could be successfully explained by considering the product of the applied electric field and its gradient, as opposed to the existing consideration of a square dependence on the applied voltage. The physics of the hitherto unreported phenomena is elucidated by developing a mathematical model, taking into consideration all of the germane forces governing the dynamics of the thin liquid film. We affirm that the present study would serve as a fundamental background for a fascinating mode of liquid actuation, with inherent application potential in several existing and novel microfluidic systems.
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Affiliation(s)
- Sri Ganesh Subramanian
- Department of Chemical Engineering , Indian Institute of Technology Kharagpur , Kharagpur 721302 , India
| | - Monojit Chakraborty
- Department of Chemical Engineering , Indian Institute of Technology Kharagpur , Kharagpur 721302 , India
| | - Srinivas Tenneti
- Department of Chemical Engineering , Indian Institute of Technology Kharagpur , Kharagpur 721302 , India
| | - Sunando DasGupta
- Department of Chemical Engineering , Indian Institute of Technology Kharagpur , Kharagpur 721302 , India
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44
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Progress toward reversible electrowetting on geometrically patterned superhydrophobic surfaces. Curr Opin Colloid Interface Sci 2018. [DOI: 10.1016/j.cocis.2018.01.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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45
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Aydogan Gokturk P, Ulgut B, Suzer S. DC Electrowetting of Nonaqueous Liquid Revisited by XPS. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:7301-7308. [PMID: 29870259 DOI: 10.1021/acs.langmuir.8b01314] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Liquid poly(ethylene glycol) (molecular weight, ∼600 Da) with a low vapor pressure is used as droplets in an ultrahigh-vacuum X-ray photoelectron spectrometer (XPS) chamber with traditional electrowetting on dielectric (EWOD) device geometry. We demonstrate that, using XPS data, independent of the sign of the applied voltage, the droplet expands on the substrate with the application of a nonzero voltage and contracts back when the voltage is brought back to zero. However, the main focus of the present investigation is about tracing the electrical potential developments on and around the droplet, using the shifts in the binding energy positions of the core levels representative of the liquid and/or the substrate in an noninvasive and chemically specific fashion, under imposed electrical fields, with an aim of shedding light on numerous models employed for simulating EWOD phenomenon, as well as on certain properties of liquid/solid interfaces. While the lateral resolution of XPS does not permit to interrogate the interface directly, we explicitly show that critical information can be extracted by probing both sides of the interface simultaneously under external bias in the form of potential steps or direct current. We find that, even though no potential drop is observed at the metal-wire electrode/liquid interface, the entire potential drop develops across the liquid/solid-substrate interface, which is faster than our probe time window (∼100 ms) and is promptly complying with the applied bias until breakdown. No indication of band bending nor additional broadening can be observed in the C 1s peak of the liquid, even under electrical field strengths exceeding 107 V/m. Moreover and surprisingly, the liquid recovers within seconds after each catastrophic breakdown. All of these findings are new and expected to contribute significantly to a better understanding of certain physicochemical properties of liquid/solid interfaces.
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Affiliation(s)
| | - Burak Ulgut
- Department of Chemistry , Bilkent University , 06800 Ankara , Turkey
| | - Sefik Suzer
- Department of Chemistry , Bilkent University , 06800 Ankara , Turkey
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46
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Zhan K, Hou X. Tunable Microscale Porous Systems with Dynamic Liquid Interfaces. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2018; 14:e1703283. [PMID: 29388386 DOI: 10.1002/smll.201703283] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Revised: 12/04/2017] [Indexed: 05/11/2023]
Abstract
Solid microscale porous material systems have attracted more attention in recent years due to their various potential applications, such as energy source transportations, biomedical devices, wastewater treatments, phase separations, etc. However, such systems are still plagued with many issues including fouling, mechanical fragility, inability to self-heal, and low recyclability that restrict them for further industrial applications. Dynamic liquid-based microscale porous material systems, especially porous surfaces and membranes, provide a new opportunity for resolving these issues and possess many benefits, such as antifouling, slippery, transparent, recovery, self-healing, and recycling properties. This Concept is mainly concerned with how to obtain tunable microscale porous systems with dynamic liquid interfaces, and their applications from the surfaces to membranes. The authors hope this concept will attract interest of scientists in areas related to the rapid development and application of various liquid-based porous systems.
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Affiliation(s)
- Kan Zhan
- State Key Laboratory of Physical Chemistry of Solid Surface, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China
- Collaborative Innovation Center of Chemistry for Energy Materials, Xiamen University, Xiamen, 361005, China
| | - Xu Hou
- State Key Laboratory of Physical Chemistry of Solid Surface, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China
- Collaborative Innovation Center of Chemistry for Energy Materials, Xiamen University, Xiamen, 361005, China
- Research Institute for Soft Matter and Biomimetics, College of Physical Science and Technology, Xiamen University, Xiamen, 361005, China
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen, 361005, China
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47
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Multanen V, Whyman G, Shulzinger E, Valtsifer V, Bormashenko E. Plasma treatment of silicone oil- infused surfaces switches impact of water droplets from bouncing to tanner-like spreading. Colloids Surf A Physicochem Eng Asp 2018. [DOI: 10.1016/j.colsurfa.2017.10.084] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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48
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Zhang H, Wang P, Zhang D. Designing a transparent organogel layer with self-repairing property for the inhibition of marine biofouling. Colloids Surf A Physicochem Eng Asp 2018. [DOI: 10.1016/j.colsurfa.2017.10.079] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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49
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Vo Q, Su H, Tran T. Universal Transient Dynamics of Electrowetting Droplets. Sci Rep 2018; 8:836. [PMID: 29339769 PMCID: PMC5770462 DOI: 10.1038/s41598-018-19167-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 12/15/2017] [Indexed: 11/09/2022] Open
Abstract
Droplet spreading on substrates by electrowetting exhibits either of the two transient behaviours: one characterised by contact line oscillation, and the other one by slow spreading dynamics. The transition between these behaviours remains elusive due to the current limited understanding of the spreading dynamics on the hydrodynamical and electrical properties of electrowetting systems. To understand this transition we propose a model capturing the transition's occurrence based on both the hydrodynamical and electrical parameters. We derive the critical viscosity at which the transition occurs and reveal its subtle and often hidden dependence on the electrowetting dynamics. We find and experimentally verify that the condition for minimization of droplets' actuation time is only achieved at the transition. Particularly, the transition time as a function of damping ratio exhibits the general feature of Kramers' reaction-rate theory.
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Affiliation(s)
- Quoc Vo
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore, Singapore
| | - Haibin Su
- Institute of Advanced Studies, Nanyang Technological University, 60 Nanyang View, 639673, Singapore, Singapore
| | - Tuan Tran
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore, Singapore.
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50
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Bansal S, Sen P. Axisymmetric and Nonaxisymmetric Oscillations of Sessile Compound Droplets in an Open Digital Microfluidic Platform. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:11047-11058. [PMID: 28918633 DOI: 10.1021/acs.langmuir.7b02042] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Manipulating droplets of biological fluids in an electrowetting on dielectric (EWOD)-based digital microfluidic platform is a significant challenge because of biofouling and surface contamination. This problem is often addressed by operating in an oil environment. We study an alternate configuration of sessile compound droplets having an aqueous core surrounded by a smaller oil shell. In contrast to the conventional EWOD platform, an open digital microfluidic platform enabled by the core-shell configuration will allow electrical, mechanical, or optical probes to get unrestricted access to the droplet, thus enabling highly flexible and dynamically reconfigurable lab-on-chip systems. Understanding droplet oscillations is essential as they are known to enhance mixing. To our knowledge, this is the first study of axisymmetric and nonaxisymmetric oscillations of compound droplets actuated using EWOD platforms. Mode shapes for both axisymmetric and nonaxisymmetric oscillations were studied and explained. Enhancement in the axisymmetric oscillation of the core by decreasing the shell volume was obtained experimentally and modeled theoretically. Smaller shell volumes reduce the damping losses, allowing the appearance of nonaxisymmetric modes over a larger range of operating parameters. The oscillation frequency regime for obtaining prominent nonaxisymmetric oscillations for different shell volumes was identified. Compound droplets provide a mechanism to reduce biofouling, sample contamination, and evaporation. We demonstrate axisymmetric and nonaxisymmetric oscillations of compound droplets with the biological core of red blood cells, providing crucial first steps for promoting applications such as rapid efficient assays, mixing of biological fluids, and fluidic photonics on hysteresis-free surfaces.
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Affiliation(s)
- Shubhi Bansal
- Centre for Nano Science and Engineering (CeNSE), Indian Institute of Science , Bangalore, Karnataka, India
| | - Prosenjit Sen
- Centre for Nano Science and Engineering (CeNSE), Indian Institute of Science , Bangalore, Karnataka, India
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