1
|
Luo T, Liu S, Zhou R, Zhang C, Chen D, Zhan Y, Hu Q, He X, Xie Y, Huan Z, Gao W, Li R, Yuan G, Wang Y, Zhou W. Contactless acoustic tweezer for droplet manipulation on superhydrophobic surfaces. LAB ON A CHIP 2023; 23:3989-4001. [PMID: 37565337 DOI: 10.1039/d3lc00365e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
Droplet manipulation on superhydrophobic surfaces (DMSS) without conventional pipetting is an emerging liquid handling technology, which can be potentially used for diagnostic, analysis, and synthetic processes. Despite notable progress, controlling droplet motion on superhydrophobic surfaces by contactless acoustic waves is rarely reported. Herein, we report a contactless acoustic tweezer (CAT) for DMSS based on establishing ultrasonic standing wave between an ultrasound transducer (UST) and a superhydrophobic substrate to manipulate droplets without physical contact. The CAT utilizes acoustic radiation forces to trap and move droplets on superhydrophobic surfaces, which allows for precise and controllable movement of droplets by controlling the movement of the UST. Small droplets with volume less than 20 μL can be levitated in mid-air for out-plane manipulation, and large droplets with volume up to 500 μL can be trapped for in-plane manipulation. Experimental results demonstrate the versatility of the CAT for manipulating droplets with various compositions and volumes on various superhydrophobic substrates, offering a versatile and cross-contamination-free liquid handling approach for applications, including but not limited to high-throughput surface-enhanced Raman scattering.
Collapse
Affiliation(s)
- Tao Luo
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen, 361102, China.
- The State Key Laboratory of Fluid Power & Mechatronic Systems, Zhejiang University, Hangzhou 310027, China
| | - Sirui Liu
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen, 361102, China.
| | - Rui Zhou
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen, 361102, China.
| | - Chen Zhang
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen, 361102, China.
| | - Dongyang Chen
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen, 361102, China.
| | - Yi Zhan
- AECC Gui Zhou Liyang Aviation Power Co., Ltd., Guiyang, 550014, China
| | - Qilin Hu
- School of Aerospace Engineering, Xiamen University, Xiamen, 361102, China
| | - Xi He
- School of Aerospace Engineering, Xiamen University, Xiamen, 361102, China
| | - Yu Xie
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen, 361102, China.
| | - Zhijie Huan
- School of Electrical Engineering and Automation, Xiamen University of Technology, Xiamen, 361024, China
| | - Wendi Gao
- The State Key Laboratory for Manufacturing Systems Engineering, International Joint Laboratory for Micro/Nano Manufacturing and Measurement Technologies, Overseas Expertise Introduction Center for Micro/Nano Manufacturing and Nano Measurement Technologies Discipline Innovation, Xi'an Jiaotong University, Xi'an 710049, China
| | - Ruirui Li
- State Key Laboratory of Dynamic Measurement Technology, North University of China, Taiyuan, 030051, P.R. China
| | - Gongfa Yuan
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen, 361102, China.
| | - Yancheng Wang
- The State Key Laboratory of Fluid Power & Mechatronic Systems, Zhejiang University, Hangzhou 310027, China
| | - Wei Zhou
- Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen, 361102, China.
| |
Collapse
|
2
|
Jia R, Hoffman BN, Kozlov AV, Demos SG, Shestopalov AA. Monolayer organic thin films as particle-contamination-resistant coatings. Sci Rep 2023; 13:11387. [PMID: 37452059 PMCID: PMC10349057 DOI: 10.1038/s41598-023-37813-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 06/28/2023] [Indexed: 07/18/2023] Open
Abstract
Three organic monolayers coatings were developed and tested for their effectiveness to increase cleaning efficiency of attached microscale particles by air flows. The experiments were performed using silica substrates coated with these organic thin films and subsequently exposed to stainless-steel and silica microparticles as a model of contamination. Laser-induced-damage tests confirmed that the coatings do not affect the laser-induced-damage threshold values. The particle exposure results suggest that although the accumulation of particles is not significantly affected under the experimental conditions used in this work, the coated substrates exhibit significantly improved cleaning efficiency with a gas flow. A size-distribution analysis was conducted to study the adsorption and cleaning efficiency of particles of different sizes. It was observed that larger size (> 5-μm) particles can be removed from coated substrates with almost 100% efficiency. It was also determined that the coatings improve the cleaning efficiency of the smaller particles (≤ 5 μm) by 17% to 30% for the stainless steel metal and 19% to 38% for the silica particles.
Collapse
Affiliation(s)
- Ruobin Jia
- Laboratory for Laser Energetics, University of Rochester, Rochester, NY, 14623-1299, USA
- Department of Chemical Engineering, University of Rochester, Rochester, NY, 14627, USA
| | - Brittany N Hoffman
- Laboratory for Laser Energetics, University of Rochester, Rochester, NY, 14623-1299, USA
| | - Alexei V Kozlov
- Laboratory for Laser Energetics, University of Rochester, Rochester, NY, 14623-1299, USA
| | - Stavros G Demos
- Laboratory for Laser Energetics, University of Rochester, Rochester, NY, 14623-1299, USA
| | - Alexander A Shestopalov
- Laboratory for Laser Energetics, University of Rochester, Rochester, NY, 14623-1299, USA.
- Department of Chemical Engineering, University of Rochester, Rochester, NY, 14627, USA.
| |
Collapse
|
3
|
Goralczyk A, Bhagwat S, Mayoussi F, Nekoonam N, Sachsenheimer K, Hou P, Kotz-Helmer F, Helmer D, Rapp BE. Application of Micro/Nanoporous Fluoropolymers with Reduced Bioadhesion in Digital Microfluidics. NANOMATERIALS 2022; 12:nano12132201. [PMID: 35808037 PMCID: PMC9268009 DOI: 10.3390/nano12132201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 06/24/2022] [Accepted: 06/25/2022] [Indexed: 02/01/2023]
Abstract
Digital microfluidics (DMF) is a versatile platform for conducting a variety of biological and chemical assays. The most commonly used set-up for the actuation of microliter droplets is electrowetting on dielectric (EWOD), where the liquid is moved by an electrostatic force on a dielectric layer. Superhydrophobic materials are promising materials for dielectric layers, especially since the minimum contact between droplet and surface is key for low adhesion of biomolecules, as it causes droplet pinning and cross contamination. However, superhydrophobic surfaces show limitations, such as full wetting transition between Cassie and Wenzel under applied voltage, expensive and complex fabrication and difficult integration into already existing devices. Here we present Fluoropor, a superhydrophobic fluorinated polymer foam with pores on the micro/nanoscale as a dielectric layer in DMF. Fluoropor shows stable wetting properties with no significant changes in the wetting behavior, or full wetting transition, until potentials of 400 V. Furthermore, Fluoropor shows low attachment of biomolecules to the surface upon droplet movement. Due to its simple fabrication process, its resistance to adhesion of biomolecules and the fact it is capable of being integrated and exchanged as thin films into commercial DMF devices, Fluoropor is a promising material for wide application in DMF.
Collapse
Affiliation(s)
- Andreas Goralczyk
- Laboratory of Process Technology, NeptunLab, Department of Microsystem Engineering (IMTEK), University of Freiburg, 79110 Freiburg im Breisgau, Germany; (A.G.); (S.B.); (F.M.); (N.N.); (K.S.); (P.H.); (F.K.-H.); (B.E.R.)
| | - Sagar Bhagwat
- Laboratory of Process Technology, NeptunLab, Department of Microsystem Engineering (IMTEK), University of Freiburg, 79110 Freiburg im Breisgau, Germany; (A.G.); (S.B.); (F.M.); (N.N.); (K.S.); (P.H.); (F.K.-H.); (B.E.R.)
| | - Fadoua Mayoussi
- Laboratory of Process Technology, NeptunLab, Department of Microsystem Engineering (IMTEK), University of Freiburg, 79110 Freiburg im Breisgau, Germany; (A.G.); (S.B.); (F.M.); (N.N.); (K.S.); (P.H.); (F.K.-H.); (B.E.R.)
| | - Niloofar Nekoonam
- Laboratory of Process Technology, NeptunLab, Department of Microsystem Engineering (IMTEK), University of Freiburg, 79110 Freiburg im Breisgau, Germany; (A.G.); (S.B.); (F.M.); (N.N.); (K.S.); (P.H.); (F.K.-H.); (B.E.R.)
| | - Kai Sachsenheimer
- Laboratory of Process Technology, NeptunLab, Department of Microsystem Engineering (IMTEK), University of Freiburg, 79110 Freiburg im Breisgau, Germany; (A.G.); (S.B.); (F.M.); (N.N.); (K.S.); (P.H.); (F.K.-H.); (B.E.R.)
| | - Peilong Hou
- Laboratory of Process Technology, NeptunLab, Department of Microsystem Engineering (IMTEK), University of Freiburg, 79110 Freiburg im Breisgau, Germany; (A.G.); (S.B.); (F.M.); (N.N.); (K.S.); (P.H.); (F.K.-H.); (B.E.R.)
| | - Frederik Kotz-Helmer
- Laboratory of Process Technology, NeptunLab, Department of Microsystem Engineering (IMTEK), University of Freiburg, 79110 Freiburg im Breisgau, Germany; (A.G.); (S.B.); (F.M.); (N.N.); (K.S.); (P.H.); (F.K.-H.); (B.E.R.)
- Freiburg Materials Research Center (FMF), University of Freiburg, 79104 Freiburg im Breisgau, Germany
| | - Dorothea Helmer
- Laboratory of Process Technology, NeptunLab, Department of Microsystem Engineering (IMTEK), University of Freiburg, 79110 Freiburg im Breisgau, Germany; (A.G.); (S.B.); (F.M.); (N.N.); (K.S.); (P.H.); (F.K.-H.); (B.E.R.)
- Freiburg Materials Research Center (FMF), University of Freiburg, 79104 Freiburg im Breisgau, Germany
- Freiburg Center of Interactive Materials and Bioinspired Technologies (FIT), University of Freiburg, 79110 Freiburg im Breisgau, Germany
- Correspondence:
| | - Bastian E. Rapp
- Laboratory of Process Technology, NeptunLab, Department of Microsystem Engineering (IMTEK), University of Freiburg, 79110 Freiburg im Breisgau, Germany; (A.G.); (S.B.); (F.M.); (N.N.); (K.S.); (P.H.); (F.K.-H.); (B.E.R.)
- Freiburg Materials Research Center (FMF), University of Freiburg, 79104 Freiburg im Breisgau, Germany
- Freiburg Center of Interactive Materials and Bioinspired Technologies (FIT), University of Freiburg, 79110 Freiburg im Breisgau, Germany
| |
Collapse
|
4
|
Abbas A, Zhang C, Asad M, Waqas A, Khatoon A, Hussain S, Mir SH. Recent Developments in Artificial Super-Wettable Surfaces Based on Bioinspired Polymeric Materials for Biomedical Applications. Polymers (Basel) 2022; 14:238. [PMID: 35054645 PMCID: PMC8781395 DOI: 10.3390/polym14020238] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 12/29/2021] [Accepted: 01/02/2022] [Indexed: 02/06/2023] Open
Abstract
Inspired by nature, significant research efforts have been made to discover the diverse range of biomaterials for various biomedical applications such as drug development, disease diagnosis, biomedical testing, therapy, etc. Polymers as bioinspired materials with extreme wettable properties, such as superhydrophilic and superhydrophobic surfaces, have received considerable interest in the past due to their multiple applications in anti-fogging, anti-icing, self-cleaning, oil-water separation, biosensing, and effective transportation of water. Apart from the numerous technological applications for extreme wetting and self-cleaning products, recently, super-wettable surfaces based on polymeric materials have also emerged as excellent candidates in studying biological processes. In this review, we systematically illustrate the designing and processing of artificial, super-wettable surfaces by using different polymeric materials for a variety of biomedical applications including tissue engineering, drug/gene delivery, molecular recognition, and diagnosis. Special attention has been paid to applications concerning the identification, control, and analysis of exceedingly small molecular amounts and applications permitting high cell and biomaterial cell screening. Current outlook and future prospects are also provided.
Collapse
Affiliation(s)
- Ansar Abbas
- School of Chemistry, Xi’an Jiaotong University, Xi’an 710049, China; (A.A.); (C.Z.)
| | - Chen Zhang
- School of Chemistry, Xi’an Jiaotong University, Xi’an 710049, China; (A.A.); (C.Z.)
| | - Muhammad Asad
- Green Catalysis Center, College of Chemistry, Zhengzhou University, Zhengzhou 450001, China;
| | - Ahsan Waqas
- Key Laboratory of Applied Surface and Colloid Chemistry (Ministry of Education), School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an 710119, China;
| | - Asma Khatoon
- College of Business Administration, Imam Abdulrahman Bin Faisal University, Dammam 34212, Saudi Arabia;
| | - Sameer Hussain
- School of Chemistry, Xi’an Jiaotong University, Xi’an 710049, China; (A.A.); (C.Z.)
| | - Sajjad Husain Mir
- School of Chemistry and Advanced Materials & BioEngineering Research (AMBER) Center, Trinity College Dublin, The University of Dublin, D02 PN40 Dublin, Ireland
| |
Collapse
|
5
|
Tao R, McHale G, Reboud J, Cooper JM, Torun H, Luo J, Luo J, Yang X, Zhou J, Canyelles-Pericas P, Wu Q, Fu Y. Hierarchical Nanotexturing Enables Acoustofluidics on Slippery yet Sticky, Flexible Surfaces. NANO LETTERS 2020; 20:3263-3270. [PMID: 32233442 PMCID: PMC7227016 DOI: 10.1021/acs.nanolett.0c00005] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The ability to actuate liquids remains a fundamental challenge in smart microsystems, such as those for soft robotics, where devices often need to conform to either natural or three-dimensional solid shapes, in various orientations. Here, we propose a hierarchical nanotexturing of piezoelectric films as active microfluidic actuators, exploiting a unique combination of both topographical and chemical properties on flexible surfaces, while also introducing design concepts of shear hydrophobicity and tensile hydrophilicity. In doing so, we create nanostructured surfaces that are, at the same time, both slippery (low in-plane pinning) and sticky (high normal-to-plane liquid adhesion). By enabling fluid transportation on such arbitrarily shaped surfaces, we demonstrate efficient fluid motions on inclined, vertical, inverted, or even flexible geometries in three dimensions. Such surfaces can also be deformed and then reformed into their original shapes, thereby paving the way for advanced microfluidic applications.
Collapse
Affiliation(s)
- Ran Tao
- Faculty
of Engineering and Environment, Northumbria
University, Newcastle
upon Tyne NE1 8ST, United
Kingdom
- Shenzhen
Key Laboratory of Advanced Thin Films and Applications, College of
Physics and Energy, Shenzhen University, 518060 Shenzhen, P. R. China
| | - Glen McHale
- Faculty
of Engineering and Environment, Northumbria
University, Newcastle
upon Tyne NE1 8ST, United
Kingdom
| | - Julien Reboud
- Division
of Biomedical Engineering, James Watt School of Engineering, University of Glasgow, Glasgow G12 8LT, United Kingdom
| | - Jonathan M. Cooper
- Division
of Biomedical Engineering, James Watt School of Engineering, University of Glasgow, Glasgow G12 8LT, United Kingdom
| | - Hamdi Torun
- Faculty
of Engineering and Environment, Northumbria
University, Newcastle
upon Tyne NE1 8ST, United
Kingdom
| | - JingTing Luo
- Shenzhen
Key Laboratory of Advanced Thin Films and Applications, College of
Physics and Energy, Shenzhen University, 518060 Shenzhen, P. R. China
| | - Jikui Luo
- College
of Information Science & Electronic Engineering, Zhejiang University, Hangzhou 310027, P. R. China
| | - Xin Yang
- Department
of Electrical and Electronic Engineering, School of Engineering, Cardiff University, Cardiff CF24 3AA, United Kingdom
| | - Jian Zhou
- College of
Mechanical and Vehicle Engineering, Hunan
University, Changsha 410082, P. R. China
| | - Pep Canyelles-Pericas
- Faculty
of Engineering and Environment, Northumbria
University, Newcastle
upon Tyne NE1 8ST, United
Kingdom
| | - Qiang Wu
- Faculty
of Engineering and Environment, Northumbria
University, Newcastle
upon Tyne NE1 8ST, United
Kingdom
| | - Yongqing Fu
- Faculty
of Engineering and Environment, Northumbria
University, Newcastle
upon Tyne NE1 8ST, United
Kingdom
- E-mail:
| |
Collapse
|
6
|
Geyer F, D’Acunzi M, Sharifi-Aghili A, Saal A, Gao N, Kaltbeitzel A, Sloot TF, Berger R, Butt HJ, Vollmer D. When and how self-cleaning of superhydrophobic surfaces works. SCIENCE ADVANCES 2020; 6:eaaw9727. [PMID: 32010764 PMCID: PMC6968945 DOI: 10.1126/sciadv.aaw9727] [Citation(s) in RCA: 112] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 09/13/2019] [Indexed: 05/18/2023]
Abstract
Despite the enormous interest in superhydrophobicity for self-cleaning, a clear picture of contaminant removal is missing, in particular, on a single-particle level. Here, we monitor the removal of individual contaminant particles on the micrometer scale by confocal microscopy. We correlate this space- and time-resolved information with measurements of the friction force. The balance of capillary and adhesion force between the drop and the contamination on the substrate determines the friction force of drops during self-cleaning. These friction forces are in the range of micro-Newtons. We show that hydrophilic and hydrophobic particles hardly influence superhydrophobicity provided that the particle size exceeds the pore size or the thickness of the contamination falls below the height of the protrusions. These detailed insights into self-cleaning allow the rational design of superhydrophobic surfaces that resist contamination as demonstrated by outdoor environmental (>200 days) and industrial standardized contamination experiments.
Collapse
Affiliation(s)
- Florian Geyer
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Maria D’Acunzi
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | | | - Alexander Saal
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Nan Gao
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Future Industries Institute, University of South Australia, Mawson Lake Campus, South Australia 5095, Australia
| | - Anke Kaltbeitzel
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Tim-Frederik Sloot
- Evonik Resource Efficiency GmbH, Goldschmidtstraße 100, 45127 Essen, Germany
| | - Rüdiger Berger
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Hans-Jürgen Butt
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Corresponding author. (H.-J.B.); (D.V.)
| | - Doris Vollmer
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Corresponding author. (H.-J.B.); (D.V.)
| |
Collapse
|
7
|
Sun D, Böhringer KF. An active self-cleaning surface system for photovoltaic modules using anisotropic ratchet conveyors and mechanical vibration. MICROSYSTEMS & NANOENGINEERING 2020; 6:87. [PMID: 34567697 PMCID: PMC8433153 DOI: 10.1038/s41378-020-00197-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Revised: 07/01/2020] [Accepted: 07/03/2020] [Indexed: 05/02/2023]
Abstract
The purpose of this work is to develop an active self-cleaning system that removes contaminants from a solar module surface by means of an automatic, water-saving, and labor-free process. The output efficiency of a solar module can be degraded over time by dust accumulation on top of the cover glass, which is often referred to as "soiling". This paper focuses on creating an active self-cleaning surface system using a combination of microsized features and mechanical vibration. The features, which are termed anisotropic ratchet conveyors (ARCs), consist of hydrophilic curved rungs on a hydrophobic background. Two different ARC systems have been designed and fabricated with self-assembled monolayer (SAM) silane and fluoropolymer thin film (Cytop). Fabrication processes were established to fabricate these two systems, including patterning Cytop without degrading the original Cytop hydrophobicity. Water droplet transport characteristics, including anisotropic driving force, droplet resonance mode, cleaning mechanisms, and system power consumption, were studied with the help of a high-speed camera and custom-made test benches. The droplet can be transported on the ARC surface at a speed of 27 mm/s and can clean a variety of dust particles, either water-soluble or insoluble. Optical transmission was measured to show that Cytop can improve transmittance by 2.5~3.5% across the entire visible wavelength range. Real-time demonstrations of droplet transport and surface cleaning were performed, in which the solar modules achieved a 23 percentage-point gain after cleaning.
Collapse
Affiliation(s)
- Di Sun
- Department of Electrical and Computer Engineering, University of Washington, Seattle, WA 98195 USA
- Institute for Nano-Engineered Systems, University of Washington, Seattle, WA 98195 USA
| | - Karl F. Böhringer
- Department of Electrical and Computer Engineering, University of Washington, Seattle, WA 98195 USA
- Institute for Nano-Engineered Systems, University of Washington, Seattle, WA 98195 USA
| |
Collapse
|
8
|
Coudron L, McDonnell MB, Munro I, McCluskey DK, Johnston ID, Tan CK, Tracey MC. Fully integrated digital microfluidics platform for automated immunoassay; A versatile tool for rapid, specific detection of a wide range of pathogens. Biosens Bioelectron 2019; 128:52-60. [DOI: 10.1016/j.bios.2018.12.014] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 11/29/2018] [Accepted: 12/11/2018] [Indexed: 11/17/2022]
|
9
|
Chen YC, Suzuki Y, Morimoto K. Electrowetting-Dominated Instability of Cassie Droplets on Superlyophobic Pillared Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:2013-2022. [PMID: 30644752 DOI: 10.1021/acs.langmuir.8b02825] [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
The liquid-air interface of Cassie droplets on superhydrophobic/superlyophobic surfaces has been directly captured with a high-precision laser displacement meter. The measured profile of the interface shape and the critical voltage with which the Cassie-to-Wenzel transition occurs are compared against those from numerical simulations of the electric field coupled with the interface shape. Under the applied voltage, the collapsing behavior of water, glycerol, and hexadecane droplets on SU-8, CYTOP, and overhanging Si/SiO2 pillars has been uniquely identified depending on the liquid properties, the pillar geometry, and the pillar material. It is shown that, with increasing voltage, the contact angle at the three-phase contact line approaches the maximum advancing angle along the pillar sidewalls, above which the depinning from the pillar edge leads to a slide-down motion. The slide-down instability is dominant over the pull-in instability both on dielectric pillars and conductive overhanging pillars examined in the present study. It is indicated that the collapsing behavior on the present overhanging pillars is closely related to contact angle saturation in electrowetting and stick-slip motion of the contact line.
Collapse
Affiliation(s)
- Yu-Chung Chen
- Department of Mechanical Engineering , The University of Tokyo , 7-3-1 Hongo , Bunkyo-ku, Tokyo 113-8656 , Japan
| | - Yuji Suzuki
- Department of Mechanical Engineering , The University of Tokyo , 7-3-1 Hongo , Bunkyo-ku, Tokyo 113-8656 , Japan
| | - Kenichi Morimoto
- Department of Mechanical Engineering , The University of Tokyo , 7-3-1 Hongo , Bunkyo-ku, Tokyo 113-8656 , Japan
| |
Collapse
|
10
|
Sun D, Böhringer KF. Self-Cleaning: From Bio-Inspired Surface Modification to MEMS/Microfluidics System Integration. MICROMACHINES 2019; 10:E101. [PMID: 30704097 PMCID: PMC6412494 DOI: 10.3390/mi10020101] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 01/22/2019] [Accepted: 01/28/2019] [Indexed: 11/16/2022]
Abstract
This review focuses on self-cleaning surfaces, from passive bio-inspired surface modification including superhydrophobic, superomniphobic, and superhydrophilic surfaces, to active micro-electro-mechanical systems (MEMS) and digital microfluidic systems. We describe models and designs for nature-inspired self-cleaning schemes as well as novel engineering approaches, and we discuss examples of how MEMS/microfluidic systems integrate with functional surfaces to dislodge dust or undesired liquid residues. Meanwhile, we also examine "waterless" surface cleaning systems including electrodynamic screens and gecko seta-inspired tapes. The paper summarizes the state of the art in self-cleaning surfaces, introduces available cleaning mechanisms, describes established fabrication processes and provides practical application examples.
Collapse
Affiliation(s)
- Di Sun
- Department of Electrical & Computer Engineering, University of Washington, Seattle, WA 98105, USA.
| | - Karl F Böhringer
- Department of Electrical & Computer Engineering, University of Washington, Seattle, WA 98105, USA.
| |
Collapse
|
11
|
Transport velocity of droplets on ratchet conveyors. Adv Colloid Interface Sci 2018; 255:18-25. [PMID: 28927830 DOI: 10.1016/j.cis.2017.08.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2017] [Revised: 08/15/2017] [Accepted: 08/30/2017] [Indexed: 02/05/2023]
Abstract
Anisotropic ratchet conveyors (ARC) are a type of digital microfluidic system. Unlike electrowetting based systems, ARCs transport droplets through a passive, micro-patterned surface and applied orthogonal vibrations. The mechanics of droplet transport on ARC devices has yet to be as well characterized and understood as on electrowetting systems. In this work, we investigate how the design of the ARC substrate affects the droplet response to vibrations and perform the first characterization of transport velocity on ARC devices. We discovered that the design of the ARC device has a significant effect on both the transport efficiency and velocity of actuated droplets, and that the amplitude of the applied vibration can modulate the velocity of transported droplets. Finally, we show that the movement of droplet edges is not continuous but rather the sum of quantized steps between features of the ARC device. These results provide new insights into the behavior of droplets vibrated on asymmetric surface patterns and will serve as the foundation for the design and development of future lab-on-a-chip systems.
Collapse
|
12
|
Banerjee U, Sen AK. Shape evolution and splitting of ferrofluid droplets on a hydrophobic surface in the presence of a magnetic field. SOFT MATTER 2018; 14:2915-2922. [PMID: 29610807 DOI: 10.1039/c7sm02312j] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
We elucidate the phenomena of dynamic wetting, shape evolution and splitting of ferrofluid (FF) droplets on a hydrophobic surface under the influence of a magnetic field. In the case of a FF droplet interacting with a magnetic field, both surface energy and magnetic energy contribute to the total Gibb's free energy and hence the wetting phenomena. The nanoparticles in the FF droplet migrate and get accumulated at the apex of the droplet which enhances the magnetic interaction causing large deformation of the droplet. The FF droplet deformation and subsequent splitting are governed by the interplay between the magnetic Fm and surface tension Fs forces. The ratio of the forces km = (Fm/Fs) was found to be a function of the magnetic Bond number Bom and non-dimensional gap g* as km ∼ (Bom)0.3(g*)-0.86. Splitting of the FF droplets was observed for km > 1 and for km < 1, an equilibrium droplet shape was observed. The wetting behavior of the FF droplets was found to be strongly dependent on the FF concentration c - concentrated (c = 1.2%) FF droplets exhibit contact line (CL) pinning and decrease in contact angle (CA) θ with time throughout, while diluted (c = 0.6%) FF droplets show a mixed mode (CL pinning followed by constant CA). In splitting of FF droplets, the ratio of the volume of the daughter droplet to that of the parent droplet i.e. (Vd/Vp), was found to decrease with an increase in the parent droplet size Vp.
Collapse
Affiliation(s)
- U Banerjee
- Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai-600036, India.
| | | |
Collapse
|
13
|
Duc C, Vlandas A, Malliaras GG, Senez V. Electrowetting on Immersed Conducting Hydrogel. J Phys Chem B 2017; 121:9947-9956. [PMID: 28930452 DOI: 10.1021/acs.jpcb.7b07971] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Conducting polymers demonstrate an interesting ability to change their wettability at ultralow voltage (<1 V). While the conducting hydrogel poly(3,4-ethylenedioxythiophene) polystyrenesulfonate (PEDOT:PSS) is increasingly used as an interface with biology partly thanks to its mechanical properties, little is known about the electrical control of its wettability. We rely on the captive bubble technique to study this hydrogel property under relevant conditions (fully immerged). We here report that the wettability variations of PEDOT:PSS are driven by an electrowetting phenomenon in contrast to other conducting polymers which are thought to undergo wettability changes due to oxido-reduction reactions. In addition, we propose a modified electrowetting model to describe the wettability variations of PEDOT:PSS in aqueous solution under ultralow voltage and we show how these variations can be tuned in different ranges of contact angles (above or under 90°) by coating the PEDOT:PSS surface.
Collapse
Affiliation(s)
- Caroline Duc
- BioMEMS, Univ. Lille, CNRS, ISEN, UMR 8520 - IEMN , F-59000 Lille, France
| | - Alexis Vlandas
- BioMEMS, Univ. Lille, CNRS, ISEN, UMR 8520 - IEMN , F-59000 Lille, France
| | - George G Malliaras
- Department of Bioelectronics, Ecole Nationale Supérieure des Mines CMP-EMSE, MOC , 13541 Gardanne, France
| | - Vincent Senez
- BioMEMS, Univ. Lille, CNRS, ISEN, UMR 8520 - IEMN , F-59000 Lille, France
| |
Collapse
|
14
|
Improvement of droplet speed and stability in electrowetting on dielectric devices by surface polishing. BIOCHIP JOURNAL 2017. [DOI: 10.1007/s13206-017-1408-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
15
|
Hutama TJ, Oleschuk RD. Magnetically manipulated droplet splitting on a 3D-printed device to carry out a complexometric assay. LAB ON A CHIP 2017; 17:2640-2649. [PMID: 28685782 DOI: 10.1039/c7lc00629b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
A method for performing droplet actuation, splitting, and dispensing using only magnetic force and physical confinement is reported. The combination of low-friction superhydrophobic surfaces and droplets containing superparamagnetic particles is demonstrated to reliably dispense droplets with a precision (≤6%) similar to standard air-displacement pipettes. The 3D printed microfluidic chips incorporate individual wells, a weir structure and differential channel depths to facilitate droplet splitting in differing ratios. Both empirical observations and numerical simulations show that the splitting is a combination of wetting and pressure differences. The method enables a parent drop to be dispensed and split into droplets ranging in size from 5-20 μL using different well volumes. Once dispensed/split the droplets can be further actuated, merged and mixed. An EDTA-based complexometric colorimetric titration for water hardness is conducted on-chip. The degree of colour change is then determined utilizing a cell phone camera and image analysis and used to calculate water hardness; this measurement was found to agree with the traditional, larger scale method. The simple, robust dispensing method is adaptable to other digital microfluidic assays.
Collapse
Affiliation(s)
- T J Hutama
- Department of Chemistry, Queen's University, 90 Bader Lane, Kingston, Ontario K7L 3N6, Canada.
| | | |
Collapse
|
16
|
Shirani E, Razmjou A, Tavassoli H, Landarani-Isfahani A, Rezaei S, Abbasi Kajani A, Asadnia M, Hou J, Ebrahimi Warkiani M. Strategically Designing a Pumpless Microfluidic Device on an "Inert" Polypropylene Substrate with Potential Application in Biosensing and Diagnostics. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:5565-5576. [PMID: 28489410 DOI: 10.1021/acs.langmuir.7b00537] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
This study is an attempt to make a step forward to implement the very immature concept of pumpless transportation of liquid into a real miniaturized device or lab-on-chip (LOC) on a plastic substrate. "Inert" plastic materials such as polypropylene (PP) are used in a variety of biomedical applications but their surface engineering is very challenging. Here, it was demonstrated that with a facile innovative wettability patterning route using fluorosilanized UV-independent TiO2 nanoparticle coating it is possible to create wedge-shaped open microfluidic tracks on inert solid surfaces for low-cost biomedical devices (lab-on-plastic). For the future miniaturization and integration of the tracks into a device, a variety of characterization techniques were used to not only systematically study the surface patterning chemistry and topography but also to have a clear knowledge of its biological interactions and performance. The effect of such surface architecture on the biological performance was studied in terms of static/dynamic protein (bovine serum albumin) adsorption, bacterial (Staphylococcus aureus and Staphylococcus epidermidis) adhesion, cell viability (using HeLa and MCF-7 cancer cell lines as well as noncancerous human fibroblast cells), and cell patterning (Murine embryonic fibroblasts). Strategies are discussed for incorporating such a confined track into a diagnostic device in which its sensing portion is based on protein, microorganism, or cells. Finally, for the proof-of-principle of biosensing application, the well-known high-affinity molecular couple of BSA-antiBSA as a biological model was employed.
Collapse
Affiliation(s)
- Elham Shirani
- Department of Biotechnology, Faculty of Advanced Sciences and Technologies, University of Isfahan , Isfahan 81746-73441, Iran
| | - Amir Razmjou
- Department of Biotechnology, Faculty of Advanced Sciences and Technologies, University of Isfahan , Isfahan 81746-73441, Iran
| | - Hossein Tavassoli
- School of Mechanical and Manufacturing Engineering, Australian Centre for NanoMedicine, University of New South Wales , Sydney, New South Wales 2052, Australia
| | | | - Saghar Rezaei
- Department of Chemistry, University of Isfahan , Isfahan 81746-73441, Iran
| | - Abolghasem Abbasi Kajani
- Department of Biotechnology, Faculty of Advanced Sciences and Technologies, University of Isfahan , Isfahan 81746-73441, Iran
| | - Mohsen Asadnia
- Department of Engineering, Macquarie University , Sydney, New South Wales 2109, Australia
| | - Jingwei Hou
- UNESCO Centre for Membrane Science and Technology, School of Chemical Science and Engineering, The University of New South Wales , Sydney, New South Wales 2052, Australia
| | - Majid Ebrahimi Warkiani
- School of Mechanical and Manufacturing Engineering, Australian Centre for NanoMedicine, University of New South Wales , Sydney, New South Wales 2052, Australia
| |
Collapse
|
17
|
Latip EA, Coudron L, McDonnell MB, Johnston ID, McCluskey DK, Day R, Tracey MC. Protein droplet actuation on superhydrophobic surfaces: a new approach toward anti-biofouling electrowetting systems. RSC Adv 2017. [DOI: 10.1039/c7ra10920b] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Anti-biofouling behaviour of an electrowetting device using off-the-shelf superhydrophobic materials is demonstrated through protein adsorption measurement and protein-laden droplet actuation.
Collapse
Affiliation(s)
| | - L. Coudron
- School of Engineering and Technology
- University of Hertfordshire
- UK
| | - M. B. McDonnell
- School of Engineering and Technology
- University of Hertfordshire
- UK
- Dstl Porton Down
- Salisbury
| | - I. D. Johnston
- School of Engineering and Technology
- University of Hertfordshire
- UK
| | - D. K. McCluskey
- School of Engineering and Technology
- University of Hertfordshire
- UK
| | - R. Day
- School of Engineering and Technology
- University of Hertfordshire
- UK
| | - M. C. Tracey
- School of Engineering and Technology
- University of Hertfordshire
- UK
| |
Collapse
|
18
|
|
19
|
Shin S, Seo J, Han H, Kang S, Kim H, Lee T. Bio-Inspired Extreme Wetting Surfaces for Biomedical Applications. MATERIALS (BASEL, SWITZERLAND) 2016; 9:E116. [PMID: 28787916 PMCID: PMC5456462 DOI: 10.3390/ma9020116] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 02/04/2016] [Accepted: 02/15/2016] [Indexed: 12/11/2022]
Abstract
Biological creatures with unique surface wettability have long served as a source of inspiration for scientists and engineers. More specifically, materials exhibiting extreme wetting properties, such as superhydrophilic and superhydrophobic surfaces, have attracted considerable attention because of their potential use in various applications, such as self-cleaning fabrics, anti-fog windows, anti-corrosive coatings, drag-reduction systems, and efficient water transportation. In particular, the engineering of surface wettability by manipulating chemical properties and structure opens emerging biomedical applications ranging from high-throughput cell culture platforms to biomedical devices. This review describes design and fabrication methods for artificial extreme wetting surfaces. Next, we introduce some of the newer and emerging biomedical applications using extreme wetting surfaces. Current challenges and future prospects of the surfaces for potential biomedical applications are also addressed.
Collapse
Affiliation(s)
- Sera Shin
- Nanobio Device Laboratory, School of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-Gu, Seoul 03722, Korea.
| | - Jungmok Seo
- Nanobio Device Laboratory, School of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-Gu, Seoul 03722, Korea.
| | - Heetak Han
- Nanobio Device Laboratory, School of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-Gu, Seoul 03722, Korea.
| | - Subin Kang
- Nanobio Device Laboratory, School of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-Gu, Seoul 03722, Korea.
| | - Hyunchul Kim
- Nanobio Device Laboratory, School of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-Gu, Seoul 03722, Korea.
| | - Taeyoon Lee
- Nanobio Device Laboratory, School of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-Gu, Seoul 03722, Korea.
| |
Collapse
|
20
|
Liu C, Liao SC, Song J, Mauk MG, Li X, Wu G, Ge D, Greenberg RM, Yang S, Bau HH. A high-efficiency superhydrophobic plasma separator. LAB ON A CHIP 2016; 16:553-60. [PMID: 26732765 PMCID: PMC4729584 DOI: 10.1039/c5lc01235j] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
To meet stringent limit-of-detection specifications for low abundance target molecules, a relatively large volume of plasma is needed for many blood-based clinical diagnostics. Conventional centrifugation methods for plasma separation are not suitable for on-site testing or bedside diagnostics. Here, we report a simple, yet high-efficiency, clamshell-style, superhydrophobic plasma separator that is capable of separating a relatively large volume of plasma from several hundred microliters of whole blood (finger-prick blood volume). The plasma separator consists of a superhydrophobic top cover with a separation membrane and a superhydrophobic bottom substrate. Unlike previously reported membrane-based plasma separators, the separation membrane in our device is positioned at the top of the sandwiched whole blood film to increase the membrane separation capacity and plasma yield. In addition, the device's superhydrophobic characteristics (i) facilitates the formation of well-defined, contracted, thin blood film with a high contact angle; (ii) minimizes biomolecular adhesion to surfaces; (iii) increases blood clotting time; and (iv) reduces blood cell hemolysis. The device demonstrated a "blood in-plasma out" capability, consistently extracting 65 ± 21.5 μL of plasma from 200 μL of whole blood in less than 10 min without electrical power. The device was used to separate plasma from Schistosoma mansoni genomic DNA-spiked whole blood with a recovery efficiency of >84.5 ± 25.8%. The S. mansoni genomic DNA in the separated plasma was successfully tested on our custom-made microfluidic chip by using loop mediated isothermal amplification (LAMP) method.
Collapse
Affiliation(s)
- Changchun Liu
- Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, 210 Towne Building, 220 South 33rd St, Philadelphia, Pennsylvania 19104-6315, USA.
| | - Shih-Chuan Liao
- Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, 210 Towne Building, 220 South 33rd St, Philadelphia, Pennsylvania 19104-6315, USA. and Department of Biomechatronics Engineering, National Pingtung University of Science and Technology, Pingtung 912, Taiwan, Republic of China
| | - Jinzhao Song
- Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, 210 Towne Building, 220 South 33rd St, Philadelphia, Pennsylvania 19104-6315, USA.
| | - Michael G Mauk
- Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, 210 Towne Building, 220 South 33rd St, Philadelphia, Pennsylvania 19104-6315, USA.
| | - Xuanwen Li
- Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, USA
| | - Gaoxiang Wu
- Department of Materials Science and Engineering, 3231 Walnut Street, Philadelphia, PA 19104, USA
| | - Dengteng Ge
- Department of Materials Science and Engineering, 3231 Walnut Street, Philadelphia, PA 19104, USA
| | - Robert M Greenberg
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Shu Yang
- Department of Materials Science and Engineering, 3231 Walnut Street, Philadelphia, PA 19104, USA
| | - Haim H Bau
- Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, 210 Towne Building, 220 South 33rd St, Philadelphia, Pennsylvania 19104-6315, USA.
| |
Collapse
|
21
|
Dey R, Ghosh UU, Chakraborty S, DasGupta S. Dynamics of Electrically Modulated Colloidal Droplet Transport. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:11269-78. [PMID: 26422170 DOI: 10.1021/acs.langmuir.5b01941] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Electrically actuated transport dynamics of colloidal droplets, on a hydrophobic dielectric film covering an array of electrodes, is studied here. Specifically, the effects of the size and electrical properties (zeta-potential) of the colloidal particles on such transport characteristics are investigated. For the colloidal droplets, the application of an electrical voltage leads to additional attenuation of the local dielectric-droplet interfacial tension. This is due to the electrically triggered enhanced colloidal particle adsorption at the dielectric-droplet interface, in the immediate vicinity of the droplet three-phase contact line (TPCL). The extent of such interfacial particle adsorption, and hence, the extent of the consequential reduction in the interfacial tension, is dictated by the combined effects of the three-phase contact line spreading, particle size, the interfacial electrostatic interaction between the colloidal particles (if charged) and the charged dielectric surface above the activated electrode, and the interparticle electrostatic repulsion. The electrical driving force of varying magnitude, stemming from this altered solid-liquid interfacial tension gradient in the presence of the colloidal particles, culminates in different droplet transport velocity and droplet transfer frequency for different colloidal droplets. We substantiate the inferences from our experimental results by a quasi-steady state force balance model for colloidal droplet transport. We believe that the present work will provide an accurate framework for determining the optimal design and operational parameters for digital microfluidic chips handling colloidal droplets, as encountered in a plethora of applications.
Collapse
Affiliation(s)
- Ranabir Dey
- Department of Mechanical Engineering and ‡Department of Chemical Engineering, Indian Institute of Technology Kharagpur , West Bengal 721302, India
| | - Udita Uday Ghosh
- Department of Mechanical Engineering and ‡Department of Chemical Engineering, Indian Institute of Technology Kharagpur , West Bengal 721302, India
| | - Suman Chakraborty
- Department of Mechanical Engineering and ‡Department of Chemical Engineering, Indian Institute of Technology Kharagpur , West Bengal 721302, India
| | - Sunando DasGupta
- Department of Mechanical Engineering and ‡Department of Chemical Engineering, Indian Institute of Technology Kharagpur , West Bengal 721302, India
| |
Collapse
|
22
|
Dynamics of Electrowetting Droplet Motion in Digital Microfluidics Systems: From Dynamic Saturation to Device Physics. MICROMACHINES 2015. [DOI: 10.3390/mi6060778] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
23
|
Hong J, Lee SJ. Detaching droplets in immiscible fluids from a solid substrate with the help of electrowetting. LAB ON A CHIP 2015; 15:900-907. [PMID: 25500988 DOI: 10.1039/c4lc01049c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The detachment (or removal) of droplets from a solid surface is an indispensable process in numerous practical applications which utilize digital microfluidics, including cell-based assay, chip cooling, and particle sampling. When a droplet that is fully stretched by impacting or electrowetting is released, the conversion of stored surface energy to kinetic energy can lead to the departure of the droplet from a solid surface. Here we firstly detach sessile droplets in immiscible fluids from a hydrophobic surface by electrowetting. The physical conditions for droplet detachment depend on droplet volume, viscosity of ambient fluid, and applied voltage. Their critical conditions are determined by exploring the retracting dynamics for a wide range of driving voltages and physical properties of fluids. The relationships between physical parameters and dynamic characteristics of retracting and jumping droplets, such as contact time and jumping height, are also established. The threshold voltage for droplet detachment in oil with high viscosity is largely reduced (~70%) by electrowetting actuations with a square pulse. To examine the applicability of three-dimensional digital microfluidic (3D-DMF) platforms to biological applications such as cell culture and cell-based assays, we demonstrate the detachment of droplets containing a mixture of human umbilical vein endothelial cells (HUVECs) and collagen (concentration of 4 × 10(4) cells mL(-1)) in silicone oil with a viscosity of 0.65 cSt. Furthermore, to complement the technical limitations due to the use of a needle electrode and to demonstrate the applicability of the 3D-DMF platform with patterned electrodes to chemical analysis and synthesis, we examine the transport, merging, mixing, and detachment of droplets with different pH values on the platform. Finally, by using DC and AC electrowetting actuations, we demonstrate the detachment of oil droplets with a very low contact angle (<~13°) in water on a hydrophobic surface.
Collapse
Affiliation(s)
- Jiwoo Hong
- Center for Biofluid Flow and Biomimic Research, Department of Mechanical Engineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang 790-784, South Korea.
| | | |
Collapse
|
24
|
Gao H, Lu S, Xu W, Szunerits S, Boukherroub R. Controllable fabrication of stable superhydrophobic surfaces on iron substrates. RSC Adv 2015. [DOI: 10.1039/c5ra02890f] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A stable superhydrophobic surface with excellent corrosion resistance has been fabricated via electrochemical machining and anneal without organic modification.
Collapse
Affiliation(s)
- Haiyan Gao
- School of Chemistry
- Beijing Institute of Technology
- Beijing 100081
- P.R. China
| | - Shixiang Lu
- School of Chemistry
- Beijing Institute of Technology
- Beijing 100081
- P.R. China
- Institut d'Electronique, de Microélectronique et de Nanotechnologie
| | - Wenguo Xu
- School of Chemistry
- Beijing Institute of Technology
- Beijing 100081
- P.R. China
| | - Sabine Szunerits
- Institut d'Electronique, de Microélectronique et de Nanotechnologie
- UMR CNRS 8520
- Université Lille 1
- Cité Scientifique
- 59652 Villeneuve d'Ascq
| | - Rabah Boukherroub
- Institut d'Electronique, de Microélectronique et de Nanotechnologie
- UMR CNRS 8520
- Université Lille 1
- Cité Scientifique
- 59652 Villeneuve d'Ascq
| |
Collapse
|
25
|
Cheng Y, Lu S, Xu W, Wen H. Fabrication of Au–AlAu4–Al2O3 superhydrophobic surface and its corrosion resistance. RSC Adv 2015. [DOI: 10.1039/c4ra12909a] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A stable superhydrophobic surface with excellent corrosion resistance has been fabricated via immersion and annealing without organic modification.
Collapse
Affiliation(s)
- Yuanyuan Cheng
- School of Chemistry
- Beijing Institute of Technology
- Beijing 100081
- P.R. China
| | - Shixiang Lu
- School of Chemistry
- Beijing Institute of Technology
- Beijing 100081
- P.R. China
| | - Wenguo Xu
- School of Chemistry
- Beijing Institute of Technology
- Beijing 100081
- P.R. China
| | - Huidong Wen
- Beijing Microelectronics Technology Institute
- Beijing 100076
- P.R. China
| |
Collapse
|
26
|
Digital microfluidic processing of mammalian embryos for vitrification. PLoS One 2014; 9:e108128. [PMID: 25250666 PMCID: PMC4176959 DOI: 10.1371/journal.pone.0108128] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2014] [Accepted: 08/25/2014] [Indexed: 11/19/2022] Open
Abstract
Cryopreservation is a key technology in biology and clinical practice. This paper presents a digital microfluidic device that automates sample preparation for mammalian embryo vitrification. Individual micro droplets manipulated on the microfluidic device were used as micro-vessels to transport a single mouse embryo through a complete vitrification procedure. Advantages of this approach, compared to manual operation and channel-based microfluidic vitrification, include automated operation, cryoprotectant concentration gradient generation, and feasibility of loading and retrieval of embryos.
Collapse
|
27
|
Lapierre F, Harnois M, Coffinier Y, Boukherroub R, Thomy V. Split and flow: reconfigurable capillary connection for digital microfluidic devices. LAB ON A CHIP 2014; 14:3589-3593. [PMID: 25058858 DOI: 10.1039/c4lc00650j] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Supplying liquid to droplet-based microfluidic microsystems remains a delicate task facing the problems of coupling continuous to digital or macro- to microfluidic systems. Here, we take advantage of superhydrophobic microgrids to address this problem. Insertion of a capillary tube inside a microgrid aperture leads to a simple and reconfigurable droplet generation setup.
Collapse
Affiliation(s)
- Florian Lapierre
- Institute of Electronics, Microelectronics and Nanotechnology (IEMN), UMR CNRS 8520, University Lille 1, F-59652 Villeneuve d'Ascq, France.
| | | | | | | | | |
Collapse
|
28
|
Dorri N, Shahbazi P, Kiani A. Self-movement of water droplet at the gradient nanostructure of Cu fabricated using bipolar electrochemistry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:1376-1382. [PMID: 24417380 DOI: 10.1021/la403566b] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
This Article reports on gradient electrodeposition of copper on the surface of a bipolar electrode (BPE). The formation mechanism of the as-fabricated gradient nanostructure is discussed, and the effects of time, potential, and concentration of CuSO4 solution on the morphology of the deposited structures are investigated. Scanning electron microscopy (SEM) is used to visualize the morphology of the deposited Cu at different positions of the BPE. By scanning from the cathodic pole to the midpoint of the BPE, three distinct structures are observed; (i) nanodendrites, (ii) nanodendrites in the vicinity of nanoparticles, and (iii) nanoparticles. The BPE surface was characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) measurements. The contact angle measurement of a water droplet reveals a surface with gradient wettability. Modification of the as-electrodeposited Cu surface with 1-dodecanethiol provides self-movement of the water droplet.
Collapse
Affiliation(s)
- Najmeh Dorri
- Department of Chemistry, University of Isfahan , Isfahan 81744-73441, Iran
| | | | | |
Collapse
|
29
|
Pan Z, Dash S, Weibel JA, Garimella SV. Assessment of water droplet evaporation mechanisms on hydrophobic and superhydrophobic substrates. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:15831-41. [PMID: 24320680 DOI: 10.1021/la4045286] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Evaporation rates are predicted and important transport mechanisms identified for evaporation of water droplets on hydrophobic (contact angle ~110°) and superhydrophobic (contact angle ~160°) substrates. Analytical models for droplet evaporation in the literature are usually simplified to include only vapor diffusion in the gas domain, and the system is assumed to be isothermal. In the comprehensive model developed in this study, evaporative cooling of the interface is accounted for, and vapor concentration is coupled to local temperature at the interface. Conjugate heat and mass transfer are solved in the solid substrate, liquid droplet, and surrounding gas. Buoyancy-driven convective flows in the droplet and vapor domains are also simulated. The influences of evaporative cooling and convection on the evaporation characteristics are determined quantitatively. The liquid-vapor interface temperature drop induced by evaporative cooling suppresses evaporation, while gas-phase natural convection acts to enhance evaporation. While the effects of these competing transport mechanisms are observed to counterbalance for evaporation on a hydrophobic surface, the stronger influence of evaporative cooling on a superhydrophobic surface accounts for an overprediction of experimental evaporation rates by ~20% with vapor diffusion-based models. The local evaporation fluxes along the liquid-vapor interface for both hydrophobic and superhydrophobic substrates are investigated. The highest local evaporation flux occurs at the three-phase contact line region due to proximity to the higher temperature substrate, rather than at the relatively colder droplet top; vapor diffusion-based models predict the opposite. The numerically calculated evaporation rates agree with experimental results to within 2% for superhydrophobic substrates and 3% for hydrophobic substrates. The large deviations between past analytical models and the experimental data are therefore reconciled with the comprehensive model developed here.
Collapse
Affiliation(s)
- Zhenhai Pan
- School of Mechanical Engineering and Birck Nanotechnology Center, Purdue University , 585 Purdue Mall, West Lafayette, Indiana 47907, United States
| | | | | | | |
Collapse
|
30
|
Fellahi O, Sarma RK, Das MR, Saikia R, Marcon L, Coffinier Y, Hadjersi T, Maamache M, Boukherroub R. The antimicrobial effect of silicon nanowires decorated with silver and copper nanoparticles. NANOTECHNOLOGY 2013; 24:495101. [PMID: 24231372 DOI: 10.1088/0957-4484/24/49/495101] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The paper reports on the preparation and antibacterial activity of silicon nanowire (SiNW) substrates coated with Ag or Cu nanoparticles (NPs) against Escherichia coli (E. coli) bacteria. The substrates are easily prepared using the metal-assisted chemical etching of crystalline silicon in hydrofluoric acid/silver nitrate (HF/AgNO3) aqueous solution. Decoration of the SiNWs with metal NPs is achieved by simple immersion in HF aqueous solutions containing silver or copper salts. The SiNWs coated with Ag NPs are biocompatible with human lung adenocarcinoma epithelial cell line A549 while possessing strong antibacterial properties to E. coli. In contrast, the SiNWs decorated with Cu NPs showed higher cytotoxicity and slightly lower antibacterial activity. Moreover, it was also observed that leakage of sugars and proteins from the cell wall of E. coli in interaction with SiNWs decorated with Ag NPs is higher compared to SiNWs modified with Cu NPs.
Collapse
Affiliation(s)
- Ouarda Fellahi
- Institut de Recherche Interdisciplinaire (IRI, USR-3078), Université Lille1, Parc de la Haute Borne, 50 avenue de Halley, BP 70478, F-59658 Villeneuve d'Ascq, France. Unité de Développement de la Technologie du Silicium (UDTS), 2, Bd. Frantz Fanon, BP 140 Alger-7 merveilles, Algiers, Algeria. Laboratoire de Physique Quantique et Systèmes Dynamiques, Département de Physique, Université de Sétif, Sétif 19000, Algeria
| | | | | | | | | | | | | | | | | |
Collapse
|
31
|
Lapierre F, Coffinier Y, Boukherroub R, Thomy V. Electro-(de)wetting on superhydrophobic surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:13346-13351. [PMID: 24088024 DOI: 10.1021/la4026848] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Usually, electrowetting on superhydrophobic surfaces (EWOSS) is generated by application of an alternating current signal and often leads to droplet impalement into the structuration. To avoid this phenomenon, superhydrophobic surfaces must show robustness to high pressure. Otherwise, an external energy has to be applied to dewet the droplet from the structuration. We present, in this article, an original approach to actuate liquid droplets via a modulated EWOSS signal (MEWOSS). This technique allows the dewetting of the droplet due to periodic vibrations induced by the electrowetting actuation. In that case, it is possible to investigate a larger range of superhydrophobic surfaces under EWOSS without droplet impalement. Three different superhydrophobic surfaces, showing different degrees of impalement under EWOSS, are investigated and compared using this MEWOSS technique.
Collapse
Affiliation(s)
- Florian Lapierre
- Institute of Electronics, Microelectronics and Nanotechnology (IEMN), UMR CNRS 8520, University Lille1 , F-59652 Villeneuve d'Ascq, France
| | | | | | | |
Collapse
|
32
|
Freire SLS, Tanner B. Additive-free digital microfluidics. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:9024-30. [PMID: 23758672 DOI: 10.1021/la401616j] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Digital microfluidics, a technique for manipulation of droplets, is becoming increasingly important for the development of miniaturized platforms for laboratory processes. Despite the enthusiasm, droplet motion is frequently hindered by the desorption of proteins or other analytes to surfaces. Current approaches to minimize this unwanted surface fouling involve the addition of extra species to the droplet or its surroundings, which might be problematic depending on the droplet content. Here, a new strategy is introduced to move droplets containing cells and other analytes on solid substrates, without extra moieties; in particular, droplets with bovine serum albumin could be moved at a concentration 2000 times higher than previously reported (without additives). This capability is achieved by using a soot-based superamphiphobic surface combined with a new device geometry, which favors droplet rolling. Contrasting with electrowetting, wetting forces are not required for droplet motion.
Collapse
Affiliation(s)
- Sergio L S Freire
- Department of Mathematics, Physics and Statistics, University of the Sciences, Philadelphia, Pennsylvania 19104, United States.
| | | |
Collapse
|
33
|
Coffinier Y, Piret G, Das MR, Boukherroub R. Effect of surface roughness and chemical composition on the wetting properties of silicon-based substrates. CR CHIM 2013. [DOI: 10.1016/j.crci.2012.08.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
34
|
She Z, Li Q, Wang Z, Li L, Chen F, Zhou J. Novel method for controllable fabrication of a superhydrophobic CuO surface on AZ91D magnesium alloy. ACS APPLIED MATERIALS & INTERFACES 2012; 4:4348-4356. [PMID: 22845176 DOI: 10.1021/am3009949] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A novel method for controllable fabrication of a superhydrophobic CuO surface on AZ91D magnesium alloy is reported in this paper. Hierarchical structure composed of micro/nano-featherlike CuO was obtained by electrodeposition of Cu-Zn alloy coating and subsequently an electrochemical anodic treatment in alkaline solution. After modification with lauric acid, the surface became hydrophobicity/superhydrophobicity. The formation of featherlike CuO structures was controllable by varying the coating composition. By applying SEM, ICP-AES, and water contact angle analysis, the effects of coating composition on the surface morphology and hydrophobicity of the as-prepared surfaces were detailedly studied. The results indicated that at the optimal condition, the surface showed a good superhydrophobicity with a water contact angle as high as 155.5 ± 1.3° and a sliding angle as low as about 3°. Possible growth mechanism of featherlike CuO hierarchical structure was discussed. Additionally, the anticorrosion effect of the superhydrophobic surface was studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The interface model for anticorrosion mechanism of superhydrophobic surface in corrosive medium was proposed. Besides, the mechanical stability test indicated that the resulting superhydrophobic surfaces have good mechanical stability.
Collapse
Affiliation(s)
- Zuxin She
- School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, P.R. China
| | | | | | | | | | | |
Collapse
|
35
|
Perry G, Thomy V, Das MR, Coffinier Y, Boukherroub R. Inhibiting protein biofouling using graphene oxide in droplet-based microfluidic microsystems. LAB ON A CHIP 2012; 12:1601-4. [PMID: 22441546 DOI: 10.1039/c2lc21279j] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Biofouling or adsorption of biomolecules onto surfaces in microfluidic devices limits the type of samples which can be handled. In this paper, we take advantage of the high adsorption capacity of graphene oxide (GO) for proteins as a strategy to limit biofouling, while preserving their activity for droplet-based lab-on-chip applications.
Collapse
Affiliation(s)
- Guillaume Perry
- IEMN, UMR CNRS 852, Université Lille1, Cité Scientifique, Villeneuve d'Ascq, France
| | | | | | | | | |
Collapse
|
36
|
Perry G, Coffinier Y, Thomy V, Boukherroub R. Sliding droplets on superomniphobic zinc oxide nanostructures. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:389-395. [PMID: 22053956 DOI: 10.1021/la2035032] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
This study reports on liquid-repellency of zinc oxide nanostructures (ZnO NS). The ZnO NS are synthesized by an easy and fast chemical bath deposition technique. Three different nanostructured surfaces consisting of nanorods, flowers, and particles are prepared, depending on the deposition time and the presence of ethanolamine in the reaction mixture. Chemical functionalization of the ZnO NS with 1H,1H,2H,2H-perfluorodecyltrichlorosilane (PFTS) in liquid (PFTS L) and vapor phase (PFTS V) or through octafluorobutane (C(4)F(8)) plasma deposition led to the formation of superomniphobic surfaces. A comprehensive characterization of the wetting properties (static contact angle and contact angle hysteresis) has been performed using liquids composed of deionized water and various concentrations of ethanol (surface tension between 35 and 72.6 mN/m). Depending on the nanostructures morphology, coating nature and liquid employed, high static apparent contact angles θ ≈ 150-160°, and low contact angle hysteresis Δθ ≈ 0° are obtained. The different ZnO NS are characterized using scanning electron microscopy (SEM) and contact angle measurements. The results reported in this work permit preparation of sliding omniphobic surfaces using a simple and low cost technique.
Collapse
Affiliation(s)
- Guillaume Perry
- Institut d'Electronique, de Microélectronique et de Nanotechnologie (UMR CNRS 8520), Université Lille 1, Cité Scientifique, Avenue Poincaré-BP 60069, 59652 Villeneuve d'Ascq, France
| | | | | | | |
Collapse
|
37
|
Egatz-Gomez A, Majithia R, Levert C, Meissner KE. Super-wetting, wafer-sized silicon nanowire surfaces with hierarchical roughness and low defects. RSC Adv 2012. [DOI: 10.1039/c2ra22267a] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
|
38
|
Choi K, Ng AHC, Fobel R, Wheeler AR. Digital microfluidics. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2012; 5:413-40. [PMID: 22524226 DOI: 10.1146/annurev-anchem-062011-143028] [Citation(s) in RCA: 397] [Impact Index Per Article: 33.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Digital microfluidics (DMF) is an emerging liquid-handling technology that enables individual control over droplets on an open array of electrodes. These picoliter- to microliter-sized droplets, each serving as an isolated vessel for chemical processes, can be made to move, merge, split, and dispense from reservoirs. Because of its unique advantages, including simple instrumentation, flexible device geometry, and easy coupling with other technologies, DMF is being applied to a wide range of fields. In this review, we summarize the state of the art of DMF technology from the perspective of analytical chemistry in sections describing the theory of droplet actuation, device fabrication and integration, and applications.
Collapse
Affiliation(s)
- Kihwan Choi
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada
| | | | | | | |
Collapse
|
39
|
Seo J, Lee S, Lee J, Lee T. Guided transport of water droplets on superhydrophobic-hydrophilic patterned Si nanowires. ACS APPLIED MATERIALS & INTERFACES 2011; 3:4722-4729. [PMID: 22091585 DOI: 10.1021/am2011756] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We present a facile method to fabricate hydrophilic patterns in superhydrophobic Si nanowire (NW) arrays for guiding water droplets. The superhydrophobic Si NW arrays were obtained by simple dip-coating of dodecyltrichlorosilane (DTS). The water contact angles (CAs) of DTS-coated Si NW arrays drastically increased and saturated at the superhydrophobic regime (water CA ≥ 150°) as the lengths of NWs increased. The demonstrated superhydrophobic surfaces show an extreme water repellent property and small CA hysteresis of less than 7°, which enable the water droplets to easily roll off. The wettability of the DTS-coated Si NW arrays can be converted from superhydrophobic to hydrophilic via UV-enhanced photodecomposition of the DTS, and such wettability conversion was reproducible on the same surfaces by repeating the DTS coating and photodecomposition processes. The resulting water guiding tracks were successfully demonstrated via selective patterning of the hydrophilic region on superhydrophobic Si NW arrays, which could enable water droplets to move along defined trajectories.
Collapse
Affiliation(s)
- Jungmok Seo
- Nanobio Device Laboratory, School of Electrical and Electronic Engineering, Yonsei University, 134 Shinchon-Dong, Seodaemun-Gu, Seoul 120-749, Republic of Korea
| | | | | | | |
Collapse
|
40
|
Chakraborty D, Sudha GS, Chakraborty S, DasGupta S. Effect of submicron particles on electrowetting on dielectrics (EWOD) of sessile droplets. J Colloid Interface Sci 2011; 363:640-5. [PMID: 21855084 DOI: 10.1016/j.jcis.2011.07.077] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Revised: 07/21/2011] [Accepted: 07/22/2011] [Indexed: 11/29/2022]
Abstract
The present study elucidates the effects of included submicron-sized particles on the wetting behavior of sessile droplets under the influence of applied electric field in an electro-wetting-on-dielectric (EWOD) configuration. A thermodynamic description using an energy minimization approach is used to analyze the experimental results related to the effects of the included particles on the EWOD phenomenon, considering the effects of line tension as well. The effects of particle size and concentration on interfacial areas are included in the model to analyze the wetting characteristics. Experiments are also conducted with submicron-sizes latex beads, in an effort to elucidate the related phenomena. It is further postulated that these beads act as suspended dielectrics in the droplet, thereby mimicking a system of two capacitors in series. An effective electrical permittivity of the composite medium is used to study the experimental results related to contact angle changes at different concentrations and diameters of submicron particles in the droplet.
Collapse
Affiliation(s)
- Debapriya Chakraborty
- Department of Mechanical Engineering, Indian Institute of Technology, Kharagpur, India
| | | | | | | |
Collapse
|
41
|
Au SH, Kumar P, Wheeler AR. A new angle on pluronic additives: advancing droplets and understanding in digital microfluidics. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:8586-94. [PMID: 21651299 DOI: 10.1021/la201185c] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Biofouling in microfluidic devices limits the type of samples which can be handled and the duration for which samples can be manipulated. Despite the cost of disposing fouled devices, relatively few strategies have been developed to tackle this problem. Here, we have analyzed a series of eight amphiphilic droplet additives, Pluronic coblock polymers of poly(propylene oxide) (PPO) and poly(ethylene oxide) (PEO), as a solution to biofouling in digital microfluidics using serum-containing cell culture media as a model fluid. Our analysis shows that species with longer PPO chains are superior for enabling droplet motion and reducing biofouling. Two of the tested species, L92 and P105, were found to lengthen device lifetimes by 2-3 times relative to additives used previously when used at optimal concentrations. Pluronics with low PEO content such as L92 were found to be cytotoxic to an immortalized mammalian cell line, and therefore we recommend that Pluronic additives with greater or equal to 50% PEO composition, such as P105, be used for digital microfluidic applications involving cells. Finally, contact angle measurements were used to probe the interaction between Pluronic-containing droplets and device surfaces. Strong correlations were found between various types of contact angle measurements and the capacity of additives to reduce biofouling, which suggests that contact angle measurements may be useful as a tool for rapidly screening new candidates for the potential to reduce biofouling. We propose that this study will be useful for scientists and engineers who are developing digital microfluidic platforms for a wide range of applications involving protein-containing solutions, and in particular, for applications involving cells.
Collapse
Affiliation(s)
- Sam H Au
- Institute for Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, ON, M5S 3G9
| | | | | |
Collapse
|
42
|
Lapierre F, Piret G, Drobecq H, Melnyk O, Coffinier Y, Thomy V, Boukherroub R. High sensitive matrix-free mass spectrometry analysis of peptides using silicon nanowires-based digital microfluidic device. LAB ON A CHIP 2011; 11:1620-1628. [PMID: 21423926 DOI: 10.1039/c0lc00716a] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We present for the first time an electrowetting on dielectric (EWOD) microfluidic system coupled to a surface-assisted laser desorption-ionization (SALDI) silicon nanowire-based interface for mass spectrometry (MS) analysis of small biomolecules. Here, the transfer of analytes has been achieved on specific locations on the SALDI interface followed by their subsequent mass spectrometry analysis without the use of an organic matrix. To achieve this purpose, a device comprising a digital microfluidic system and a patterned superhydrophobic/superhydrophilic silicon nanowire interface was developed. The digital microfluidic system serves for the displacement of the droplets containing analytes, via an electrowetting actuation, inside the superhydrophilic patterns. The nanostructured silicon interface acts as an inorganic target for matrix-free laser desorption-ionization mass spectrometry analysis of the dried analytes. The proposed device can be easily used to realize several basic operations of a Lab-on-Chip such as analyte displacement and rinsing prior to MS analysis. We have demonstrated that the analysis of low molecular weight compounds (700 m/z) can be achieved with a very high sensitivity (down to 10 fmol μL(-1)).
Collapse
|