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Choubey A, Dubey K, Bahga SS. Rapid prototyping of polydimethylsiloxane (PDMS) microchips using electrohydrodynamic jet printing: Application to electrokinetic assays. Electrophoresis 2023; 44:725-732. [PMID: 36774545 DOI: 10.1002/elps.202200241] [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: 10/03/2022] [Revised: 02/03/2023] [Accepted: 02/06/2023] [Indexed: 02/13/2023]
Abstract
Polydimethylsiloxane (PDMS) based microfluidic devices have found increasing utility for electrophoretic and electrokinetic assays because of their ease of fabrication using replica molding. However, the fabrication of high-resolution molds for replica molding still requires the resource-intensive and time-consuming photolithography process, which precludes quick design iterations and device optimization. We here demonstrate a low-cost, rapid microfabrication process, based on electrohydrodynamic jet printing (EJP), for fabricating non-sacrificial master molds for replica molding of PDMS microfluidic devices. The method is based on the precise deposition of an electrically stretched polymeric solution of polycaprolactone in acetic acid on a silicon wafer placed on a computer-controlled motion stage. This process offers the high-resolution (order 10 μ $\umu$ m) capability of photolithography and rapid prototyping capability of inkjet printing to print high-resolution templates for elastomeric microfluidic devices within a few minutes. Through proper selection of the operating parameters such as solution flow rate, applied electric field, and stage speed, we demonstrate microfabrication of intricate master molds and corresponding PDMS microfluidic devices for electrokinetic applications. We demonstrate the utility of the fabricated PDMS microchips for nonlinear electrokinetic processes such as electrokinetic instability and controlled sample splitting in ITP. The ability to rapid prototype customized reusable master molds with order 10 μ $\umu$ m resolution within a few minutes can help in designing and optimizing microfluidic devices for various electrokinetic applications.
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Affiliation(s)
- Anupam Choubey
- Department of Mechanical Engineering, Indian Institute of Technology Delhi, New Delhi, India
| | - Kaushlendra Dubey
- Department of Mechanical Engineering, Indian Institute of Technology Delhi, New Delhi, India
| | - Supreet Singh Bahga
- Department of Mechanical Engineering, Indian Institute of Technology Delhi, New Delhi, India
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2
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Hrynevich A, Li Y, Cedillo-Servin G, Malda J, Castilho M. (Bio)fabrication of microfluidic devices and organs-on-a-chip. 3D Print Med 2023. [DOI: 10.1016/b978-0-323-89831-7.00001-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
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3
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Duan Y, Yang W, Xiao J, Gao J, Wei L, Huang Y, Yin Z. High density, addressable electrohydrodynamic printhead made of a silicon plate and polymer nozzle structure. LAB ON A CHIP 2022; 22:3877-3884. [PMID: 36073597 DOI: 10.1039/d2lc00624c] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Electrohydrodynamic (EHD) printing is a promising micro/nanofabrication technique, due to its ultra-high resolution and wide material applicability. However, it suffers from low printing efficiency which urgently calls for a high density and addressable nozzle array. This paper presents a nozzle array chip made of a silicon plate and polymer nozzle structure, where the large silicon plate is conducive to a uniform spatial electric field distribution, and the polymer SU8 nozzle can inhibit tip discharge due to its insulating character and liquid flooding as SU8 is hydrophobic. By carefully designing the nozzle array structure via simulation, and fabricating it through MEMS technology, a high-density nozzle array chip has been achieved which can generate very uniform dots without crosstalk. Meanwhile, by adding extractors underneath the nozzle array, and utilizing a digital switch array to tune their on/off state, addressable printing has been realized. This novel printhead design has solved the discharge, liquid flooding, and crosstalk behavior in EHD nozzle arrays, and is compatible with traditional silicon-based MEMS technology, which will promote the practical applications of EHD printing in micro/nanoelectronics, biomedical/energy devices, etc.
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Affiliation(s)
- Yongqing Duan
- State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan 430074, P. R. China.
- Flexible Electronics Research Center, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Weili Yang
- State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan 430074, P. R. China.
| | - Jingjing Xiao
- State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan 430074, P. R. China.
| | - Jixin Gao
- State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan 430074, P. R. China.
| | - Lai Wei
- State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan 430074, P. R. China.
| | - YongAn Huang
- State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan 430074, P. R. China.
- Flexible Electronics Research Center, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Zhouping Yin
- State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan 430074, P. R. China.
- Flexible Electronics Research Center, Huazhong University of Science and Technology, Wuhan 430074, China
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4
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Microfabrication Bonding Process Optimization for a 3D Multi-Layer PDMS Suspended Microfluidics. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12094626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Microfluidic systems have received increased attention due to their wide variety of applications, from chemical sensing to biological detection to medical analysis. Microfluidics used to be fabricated by using etching techniques that required cleanroom and aggressive chemicals. However, another microfluidic fabrication technique, namely, soft lithography, is less expensive and safer compared to former techniques. Polydimethylsiloxane (PDMS) has been widely employed as a fabrication material in microfluidics by using soft lithography as it is transparent, soft, bio-compatible, and inexpensive. In this study, a 3D multi-layer PDMS suspended microfluidics fabrication process using soft lithography is presented, along with its manufacturing issues that may deteriorate or compromise the microsystem’s test results. The main issues considered here are bonding strength and trapped air-bubbles, specifically in multi-layer PDMS microfluidics. In this paper, these two issues have been considered and resolved by optimizing curing temperature and air-vent channel integration to a microfluidic platform. Finally, the suspended microfluidic system has been tested in various experiments to prove its sensitivity to different fluids and flow rates.
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Mkhize N, Bhaskaran H. Electrohydrodynamic Jet Printing: Introductory Concepts and Considerations. SMALL SCIENCE 2021. [DOI: 10.1002/smsc.202100073] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Affiliation(s)
- Nhlakanipho Mkhize
- Department of Materials University of Oxford Parks Road Oxford OX1 3PH UK
| | - Harish Bhaskaran
- Department of Materials University of Oxford Parks Road Oxford OX1 3PH UK
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6
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Mi Y, Liu X, Gao Z, Wang M, Shi L, Zhang X, Gao K, Mugisha ER, Yan W. 3D Photovoltaic Router of Water Microdroplets Aiming at Free-Space Microfluidic Transportation. ACS APPLIED MATERIALS & INTERFACES 2021; 13:45018-45032. [PMID: 34482685 DOI: 10.1021/acsami.1c10940] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
So far, microfluidic navigation based on space-charge modulation is limited in a two-dimensional (2D) substrate plane. In this paper, a three-dimensional (3D) photovoltaic water-microdroplet router based on a superhydrophobic LiNbO3:Fe crystal is reported. This router employs the repulsive electrostatic force induced by the positive photovoltaic charges generated under focused laser illumination and permits traveling microdroplets to be routed in both in-plane and out-of-plane ways. By analyzing the dynamic process of microdroplet routing, it is found that the microdroplets can gain positive charges through traveling on a superhydrophobic surface and that the positive photovoltaic charges exert an electrophoretic (EP) force on the microdroplets being charged and make them either routed inside the 2D substrate plane or jump out of the 2D plane through electrostatic ballistic ejection. The laser-illumination and microdroplet-size dependence of the deflecting parameters of the in-plane microdroplet routing as well as the jumping trajectory of the out-of-plane routing are investigated. An electrostatic kinetic model is established for both routing ways, and the simulation based on this model predicts well the experimental dependence. A few examples of cascaded free-space microfluidic transportation using the 3D photovoltaic router are demonstrated, showing the potential of this technique in future biological applications.
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Affiliation(s)
- Yuhang Mi
- School of Materials Science and Engineering, Hebei Engineering Laboratory of PFC, Hebei University of Technology, Tianjin 300130, China
| | - Xiaohu Liu
- School of Materials Science and Engineering, Hebei Engineering Laboratory of PFC, Hebei University of Technology, Tianjin 300130, China
| | - Zuoxuan Gao
- School of Materials Science and Engineering, Hebei Engineering Laboratory of PFC, Hebei University of Technology, Tianjin 300130, China
| | - Mengtong Wang
- School of Materials Science and Engineering, Hebei Engineering Laboratory of PFC, Hebei University of Technology, Tianjin 300130, China
| | - Lihong Shi
- Department of Physics, Tianjin Chengjian University, Tianjin 300384, China
| | - Xiong Zhang
- School of Materials Science and Engineering, Hebei Engineering Laboratory of PFC, Hebei University of Technology, Tianjin 300130, China
| | - Kaifang Gao
- School of Materials Science and Engineering, Hebei Engineering Laboratory of PFC, Hebei University of Technology, Tianjin 300130, China
| | - Euphrem Rwagasore Mugisha
- School of Materials Science and Engineering, Hebei Engineering Laboratory of PFC, Hebei University of Technology, Tianjin 300130, China
| | - Wenbo Yan
- School of Materials Science and Engineering, Hebei Engineering Laboratory of PFC, Hebei University of Technology, Tianjin 300130, China
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7
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Inkjet Printing of Flexible Transparent Conductive Films with Silver Nanowires Ink. NANOMATERIALS 2021; 11:nano11061571. [PMID: 34203673 PMCID: PMC8232118 DOI: 10.3390/nano11061571] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 06/04/2021] [Accepted: 06/07/2021] [Indexed: 11/23/2022]
Abstract
The inkjet printing process is a promising electronic printing technique for large-scale, printed, flexible and stretchable electronics because of features such as its high manufacturing speed, environmental friendliness, simple process, low cost, accurate positioning, and so on. As the base material of printed conductive patterns, conductive ink is the foundation of the development of printed electronics technology, and directly affects the performance and the quality of electronic products. In this paper, conductive ink with silver nanowires (AgNWs) was prepared, with AgNWs of lengths of 2–5 µm and diameters of 20 nm or so, isopropyl alcohol and ethylene glycol as the mixed solvents, and modified polysilane as the wetting agent. We discussed the relationship between the formula of the AgNWs ink and the surface tension, viscosity, contact angle between ink droplet and poly(ethylene) terephthalate (PET) surface, as well as the film-forming properties of the ink. Further, we analyzed the effects of the number of printed layers and the ink concentration of the AgNWs on the microstructures, photoelectric properties and accuracy of the printed patterns, as well as the change in the sheet resistance of the film during different bending cycles. The experimental results show that flexible transparent conductive patterns with a light transmittance of 550 nm of 83.1–88.4% and a sheet resistance of 34.0 Ω∙sq−1–78.3 nm∙sq−1 can be obtained by using AgNWs ink of 0.38 mg∙mL−1 to 0.57 mg∙mL−1, a poly (ethylene terephthalate) (PET) substrate temperature of 40 °C, a nozzle temperature of 35 °C, and heat treated at 60 °C for 10 min. These performances indicate the excellent potential of the inkjet printing of AgNWs networks for developing flexible transparent conductive film.
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Gao Z, Mi Y, Wang M, Liu X, Zhang X, Gao K, Shi L, Mugisha ER, Chen H, Yan W. Hydrophobic-substrate based water-microdroplet manipulation through the long-range photovoltaic interaction from a distant LiNbO 3:Fe crystal. OPTICS EXPRESS 2021; 29:3808-3824. [PMID: 33770973 DOI: 10.1364/oe.417225] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 01/16/2021] [Indexed: 06/12/2023]
Abstract
Development of photovoltaic water-microdroplet manipulation using LN:Fe crystals has to meet the requirement of the hybrid and heating-avoided design of biological lab-on-chips. To fulfill this, we demonstrate a successful manipulation of a water microdroplet on a hydrophobic substrate by utilizing the long-range photovoltaic interaction from a distant LN:Fe crystal (see Visualization 1). The maximal manipulation distance (MMD) is found to be dependent on the laser-illumination intensity at the LN:Fe crystal and it can be tuned up to a sub-centimeter level (∼4 mm). Basing on the two-center model of light-induced charge transport in the LN:Fe crystal, we establish an analytic model to describe the force balance during the microdroplet manipulation under a long-range photovoltaic interaction. Either shortening the manipulation distance or increasing the illumination intensity can enhance the photovoltaic interaction and increase the velocity of the microdroplet being manipulated. An abrupt shape change followed by a fast repelling movement of the water microdroplet is observed under a strong photovoltaic interaction (see Visualization 2).
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Kim YJ, Lim JH, Lee JM, Choi JW, Choi HW, Seo WH, Lee KG, Lee SJ, Chung BG. CuS/rGO-PEG Nanocomposites for Photothermal Bonding of PMMA-Based Plastic Lab-on-a-Chip. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:176. [PMID: 33445759 PMCID: PMC7828185 DOI: 10.3390/nano11010176] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 12/28/2020] [Accepted: 01/10/2021] [Indexed: 11/16/2022]
Abstract
We developed copper sulfide (CuS)/reduced graphene oxide (rGO)-poly (ethylene glycol) (PEG) nanocomposites for photothermal bonding of a polymethyl methacrylate (PMMA)-based plastic lab-on-a-chip. The noncontact photothermal bonding of PMMA-based plastic labs-on-chip plays an important role in improving the stability and adhesion at a high-temperature as well as minimizing the solution leakage from microchannels when connecting two microfluidic devices. The CuS/rGO-PEG nanocomposites were used to bond a PMMA-based plastic lab-on-a-chip in a short time with a high photothermal effect by a near-infrared (NIR) laser irradiation. After the thermal bonding process, a gap was not generated in the PMMA-based plastic lab-on-a-chip due to the low viscosity and density of the CuS/rGO-PEG nanocomposites. We also evaluated the physical and mechanical properties after the thermal bonding process, showing that there was no solution leakage in PMMA-based plastic lab-on-a-chip during polymerase chain reaction (PCR) thermal cycles. Therefore, the CuS/rGO-PEG nanocomposite could be a potentially useful nanomaterial for non-contact photothermal bonding between the interfaces of plastic module lab-on-a-chip.
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Affiliation(s)
- Young Jae Kim
- Department of Mechanical Engineering, Sogang University, Seoul 04107, Korea; (Y.J.K.); (J.W.C.); (H.W.C.)
| | - Jae Hyun Lim
- Department of Biomedical Engineering, Sogang University, Seoul 04107, Korea; (J.H.L.); (W.H.S.)
| | - Jong Min Lee
- Division of Chemical Industry, Yeungnam University College, Daegu 38541, Korea;
| | - Ji Wook Choi
- Department of Mechanical Engineering, Sogang University, Seoul 04107, Korea; (Y.J.K.); (J.W.C.); (H.W.C.)
| | - Hyung Woo Choi
- Department of Mechanical Engineering, Sogang University, Seoul 04107, Korea; (Y.J.K.); (J.W.C.); (H.W.C.)
| | - Won Ho Seo
- Department of Biomedical Engineering, Sogang University, Seoul 04107, Korea; (J.H.L.); (W.H.S.)
| | - Kyoung G. Lee
- Division of Nano-Bio Sensors/Chips Development, National NanoFab Center, Daejeon 34141, Korea; (K.G.L.); (S.J.L.)
| | - Seok Jae Lee
- Division of Nano-Bio Sensors/Chips Development, National NanoFab Center, Daejeon 34141, Korea; (K.G.L.); (S.J.L.)
| | - Bong Geun Chung
- Department of Mechanical Engineering, Sogang University, Seoul 04107, Korea; (Y.J.K.); (J.W.C.); (H.W.C.)
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10
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Akther F, Yakob SB, Nguyen NT, Ta HT. Surface Modification Techniques for Endothelial Cell Seeding in PDMS Microfluidic Devices. BIOSENSORS 2020; 10:E182. [PMID: 33228050 PMCID: PMC7699314 DOI: 10.3390/bios10110182] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 11/13/2020] [Accepted: 11/15/2020] [Indexed: 12/14/2022]
Abstract
Microfluidic lab-on-a-chip cell culture techniques have been gaining popularity by offering the possibility of reducing the amount of samples and reagents and greater control over cellular microenvironment. Polydimethylsiloxane (PDMS) is the commonly used polymer for microfluidic cell culture devices because of the cheap and easy fabrication techniques, non-toxicity, biocompatibility, high gas permeability, and optical transparency. However, the intrinsic hydrophobic nature of PDMS makes cell seeding challenging when applied on PDMS surface. The hydrophobicity of the PDMS surface also allows the non-specific absorption/adsorption of small molecules and biomolecules that might affect the cellular behaviour and functions. Hydrophilic modification of PDMS surface is indispensable for successful cell seeding. This review collates different techniques with their advantages and disadvantages that have been used to improve PDMS hydrophilicity to facilitate endothelial cells seeding in PDMS devices.
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Affiliation(s)
- Fahima Akther
- Australian Institute for Bioengineering and Nanotechnology, the University of Queensland, Brisbane, QLD 4072, Australia;
- Queensland Micro-and Nanotechnology Centre, Griffith University, Brisbane, QLD 4111, Australia;
| | - Shazwani Binte Yakob
- School of Pharmacy, the University of Queensland, Brisbane, QLD 4102, Australia;
| | - Nam-Trung Nguyen
- Queensland Micro-and Nanotechnology Centre, Griffith University, Brisbane, QLD 4111, Australia;
| | - Hang T. Ta
- Australian Institute for Bioengineering and Nanotechnology, the University of Queensland, Brisbane, QLD 4072, Australia;
- Queensland Micro-and Nanotechnology Centre, Griffith University, Brisbane, QLD 4111, Australia;
- School of Environment and Science, Griffith University, Brisbane, QLD 4111, Australia
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11
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Shoda K, Tanaka M, Mino K, Kazoe Y. A Simple Low-Temperature Glass Bonding Process with Surface Activation by Oxygen Plasma for Micro/Nanofluidic Devices. MICROMACHINES 2020; 11:E804. [PMID: 32854246 PMCID: PMC7570177 DOI: 10.3390/mi11090804] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 08/11/2020] [Accepted: 08/23/2020] [Indexed: 12/18/2022]
Abstract
The bonding of glass substrates is necessary when constructing micro/nanofluidic devices for sealing micro- and nanochannels. Recently, a low-temperature glass bonding method utilizing surface activation with plasma was developed to realize micro/nanofluidic devices for various applications, but it still has issues for general use. Here, we propose a simple process of low-temperature glass bonding utilizing typical facilities available in clean rooms and applied it to the fabrication of micro/nanofluidic devices made of different glasses. In the process, the substrate surface was activated with oxygen plasma, and the glass substrates were placed in contact in a class ISO 5 clean room. The pre-bonded substrates were heated for annealing. We found an optimal concentration of oxygen plasma and achieved a bonding energy of 0.33-0.48 J/m2 in fused-silica/fused-silica glass bonding. The process was applied to the bonding of fused-silica glass and borosilicate glass, which is generally used in optical microscopy, and revealed higher bonding energy than fused-silica/fused-silica glass bonding. An annealing temperature lower than 200 °C was necessary to avoid crack generation by thermal stress due to the different thermal properties of the glasses. A fabricated micro/nanofluidic device exhibited a pressure resistance higher than 600 kPa. This work will contribute to the advancement of micro/nanofluidics.
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Affiliation(s)
| | | | | | - Yutaka Kazoe
- Department of System Design Engineering, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku, Kanagawa 223-8522, Japan; (K.S.); (M.T.); (K.M.)
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12
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Direct Ink Writing Technology (3D Printing) of Graphene-Based Ceramic Nanocomposites: A Review. NANOMATERIALS 2020; 10:nano10071300. [PMID: 32630782 PMCID: PMC7407564 DOI: 10.3390/nano10071300] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 06/27/2020] [Indexed: 12/19/2022]
Abstract
In the present work, the state of the art of the most common additive manufacturing (AM) technologies used for the manufacturing of complex shape structures of graphene-based ceramic nanocomposites, ceramic and graphene-based parts is explained. A brief overview of the AM processes for ceramic, which are grouped by the type of feedstock used in each technology, is presented. The main technical factors that affect the quality of the final product were reviewed. The AM processes used for 3D printing of graphene-based materials are described in more detail; moreover, some studies in a wide range of applications related to these AM techniques are cited. Furthermore, different feedstock formulations and their corresponding rheological behavior were explained. Additionally, the most important works about the fabrication of composites using graphene-based ceramic pastes by Direct Ink Writing (DIW) are disclosed in detail and illustrated with representative examples. Various examples of the most relevant approaches for the manufacturing of graphene-based ceramic nanocomposites by DIW are provided.
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13
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Wang Y, Wang Y, Mei D. Scalable Printing of Bionic Multiscale Channel Networks Through Digital Light Processing-Based Three-Dimensional Printing Process. 3D PRINTING AND ADDITIVE MANUFACTURING 2020; 7:115-125. [PMID: 36655197 PMCID: PMC9586228 DOI: 10.1089/3dp.2020.0025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Digital light processing (DLP)-based printing process has been used to print microfeature-sized constructs and architectures for biomedical applications; the key challenge is to achieve both large printing size and high accuracy at the same time. Here we reported a scalable DLP-based three-dimensional (3D) printing system with scalable resolution and building size, which was used for printing of multiscale hydrogel fractal bionic channels. Scalable printing was achieved by moving the convex lens of the printing system, and thus, each single micromirror of the digital micromirror device chip corresponded to the single-pixel size scaling from 6 to12 μm. Using this system, we were able to use poly (ethylene glycol) diacrylate to fabricate a variety of multiscale architectures, such as regular fractal Y-shaped channels, and more irregular and intricate geometries, such as biomimetic capillary vascular networks. Blue and red food dye solutions were able to freely fill all these channels in the scaffolds, from the trunk (>1500 μm in width) to small branch (∼30 μm in width) by capillarity. Cell experiments were carried out to certify the biocompatibility of printed multiscale biomimetic channel networks. This work reveals significant progress in printing multiscale constructs with both large printing size and high precision in scalable DLP-based 3D printing.
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Affiliation(s)
- Yue Wang
- State Key Laboratory of Fluid Power and Mechatronic Systems, School of Mechanical Engineering, Zhejiang University, Hangzhou, China
- Key Laboratory of Advanced Manufacturing Technology of Zhejiang Province, School of Mechanical Engineering, Zhejiang University, Hangzhou, China
| | - Yancheng Wang
- State Key Laboratory of Fluid Power and Mechatronic Systems, School of Mechanical Engineering, Zhejiang University, Hangzhou, China
- Department of Aerospace and Mechanical Engineering, The George Washington University, Washington, District of Columbia, USA
| | - Deqing Mei
- State Key Laboratory of Fluid Power and Mechatronic Systems, School of Mechanical Engineering, Zhejiang University, Hangzhou, China
- Department of Aerospace and Mechanical Engineering, The George Washington University, Washington, District of Columbia, USA
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14
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Ćatić N, Wells L, Al Nahas K, Smith M, Jing Q, Keyser UF, Cama J, Kar-Narayan S. Aerosol-jet printing facilitates the rapid prototyping of microfluidic devices with versatile geometries and precise channel functionalization. APPLIED MATERIALS TODAY 2020; 19:100618. [PMID: 33521242 PMCID: PMC7821597 DOI: 10.1016/j.apmt.2020.100618] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Microfluidics has emerged as a powerful analytical tool for biology and biomedical research, with uses ranging from single-cell phenotyping to drug discovery and medical diagnostics, and only small sample volumes required for testing. The ability to rapidly prototype new designs is hugely beneficial in a research environment, but the high cost, slow turnaround, and wasteful nature of commonly used fabrication techniques, particularly for complex multi-layer geometries, severely impede the development process. In addition, microfluidic channels in most devices currently play a passive role and are typically used to direct flows. The ability to "functionalize" the channels with different materials in precise spatial locations would be a major advantage for a range of applications. This would involve incorporating functional materials directly within the channels that can partake in, guide or facilitate reactions in precisely controlled microenvironments. Here we demonstrate the use of Aerosol Jet Printing (AJP) to rapidly produce bespoke molds for microfluidic devices with a range of different geometries and precise "in-channel" functionalization. We show that such an advanced microscale additive manufacturing method can be used to rapidly design cost-efficient and customized microfluidic devices, with the ability to add functional coatings at specific locations within the microfluidic channels. We demonstrate the functionalization capabilities of our technique by specifically coating a section of a microfluidic channel with polyvinyl alcohol to render it hydrophilic. This versatile microfluidic device prototyping technique will be a powerful aid for biological and bio-medical research in both academic and industrial contexts.
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Affiliation(s)
- Nordin Ćatić
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, UK
| | - Laura Wells
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, UK
| | - Kareem Al Nahas
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Michael Smith
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, UK
| | - Qingshen Jing
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, UK
| | - Ulrich F. Keyser
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Jehangir Cama
- Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
- Corresponding author at: Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK.
| | - Sohini Kar-Narayan
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, UK
- Corresponding author at: Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, UK.
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15
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Fabrication of Microfluidic Chips Based on an EHD-Assisted Direct Printing Method. SENSORS 2020; 20:s20061559. [PMID: 32168871 PMCID: PMC7146459 DOI: 10.3390/s20061559] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 03/05/2020] [Accepted: 03/09/2020] [Indexed: 11/27/2022]
Abstract
Microfluidic chips have been widely used in many areas such as biology, environmental monitoring, and micromixing. With the increasing popularity and complexity of microfluidic systems, rapid and convenient approaches for fabricating microfluidic chips are necessary. In this study, a method based on EHD (electrohydrodynamic)-assisted direct printing is proposed. Firstly, the principle of EHD-assisted direct printing was analyzed. The influence of the operating voltage and moving speed of the work table on the width of a paraffin wax model was studied. Then, two kinds of paraffin wax molds for micromixing with channel widths of 120 μm were prepared. A polydimethylsiloxane (PDMS) micromixer was fabricated by replicating the paraffin wax mold, and the micromixing of blue and yellow dye was realized. The results show that EHD-assisted direct printing can be used to make complex microscale structures, which has the potential to greatly simplify the manufacturing process.
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Abstract
Nowadays it is easy to imagine that the exploitation of different additive manufacturing approaches could find use in regenerative medicine and frontiers nanotechnology with a strong interest in the development of in vivo bio-incubators that better replicate the tissue environment. Various electrospinning technologies have been exploited for the fabrication of composite polymeric architectures, where fibers have been used for the construction layer by layer of micro-architectures. Unfortunately, in case of processing biomaterials, the intrinsic factors of the materials could become obstacles when considering such advanced engineering methods. Here, for the first time, we use the pyro-EHD process for the fabrication of layered three-dimensional architectures made using a biodegradable and biocompatible polymer. The proposed approach for layered 3D printing works at mild temperature allowing deposition at high resolution and great flexibility in manufacturing, avoiding high voltage generators, and nozzles. The layered 3D printing, activated by the pyro-electric effect, is discussed and characterized in terms of geometrical features and processing parameters. Different geometries and micro-architecture (wall, square, triangle, and hybrid structures) have been demonstrated and over printing of composite polymer, obtained by mixing multiwall carbon nanotubes and fluorochrome, has been discussed, focusing on the use of a biodegradable and biocompatible polymer.
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Gill E, Willis S, Gerigk M, Cohen P, Zhang D, Li X, Huang YYS. Fabrication of Designable and Suspended Microfibers via Low-Voltage 3D Micropatterning. ACS APPLIED MATERIALS & INTERFACES 2019; 11:19679-19690. [PMID: 31081331 PMCID: PMC6613729 DOI: 10.1021/acsami.9b01258] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Accepted: 05/13/2019] [Indexed: 05/02/2023]
Abstract
Building two-dimensional (2D) and three-dimensional (3D) fibrous structures in the micro- and nanoscale will offer exciting prospects for numerous applications spanning from sensors to energy storage and tissue engineering scaffolds. Electrospinning is a well-suited technique for drawing micro- to nanoscale fibers, but current methods of building electrospun fibers in 3D are restrictive in terms of printed height, design of macroscopic fiber networks, and choice of polymer. Here, we combine low-voltage electrospinning and additive manufacturing as a method to pattern layers of suspended mesofibers. Layers of fibers are suspended between 3D-printed supports in situ in multiple fiber layers and designable orientations. We examine the key working parameters to attain a threshold for fiber suspension, use those behavioral observations to establish a "fiber suspension indicator", and demonstrate its utility through design of intricate suspended fiber architectures. Individual fibers produced by this method approach the micrometer/submicrometer scale, while the overall suspended 3D fiber architecture can span over a centimeter in height. We demonstrate an application of suspended fiber architectures in 3D cell culture, utilizing patterned fiber topography to guide the assembly of suspended high-cellular-density structures. The solution-based fiber suspension patterning process we report offers a unique competence in patterning soft polymers, including extracellular matrix-like materials, in a high resolution and aspect ratio. The platform could thus offer new design and manufacturing capabilities of devices and functional products by incorporating functional fibrous elements.
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Affiliation(s)
- Elisabeth
L. Gill
- Department
of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, U.K.
- The
Nanoscience Centre, University of Cambridge, 11 JJ Thomson Avenue, Cambridge CB3 0FF, U.K.
| | - Samuel Willis
- Department
of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, U.K.
| | - Magda Gerigk
- Department
of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, U.K.
- The
Nanoscience Centre, University of Cambridge, 11 JJ Thomson Avenue, Cambridge CB3 0FF, U.K.
| | - Paul Cohen
- Department
of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, U.K.
| | - Duo Zhang
- Department
of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, U.K.
- The
Nanoscience Centre, University of Cambridge, 11 JJ Thomson Avenue, Cambridge CB3 0FF, U.K.
| | - Xia Li
- Department
of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, U.K.
| | - Yan Yan Shery Huang
- Department
of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ, U.K.
- The
Nanoscience Centre, University of Cambridge, 11 JJ Thomson Avenue, Cambridge CB3 0FF, U.K.
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Coppola S, Nasti G, Vespini V, Mecozzi L, Castaldo R, Gentile G, Ventre M, Netti PA, Ferraro P. Quick liquid packaging: Encasing water silhouettes by three-dimensional polymer membranes. SCIENCE ADVANCES 2019; 5:eaat5189. [PMID: 31139742 PMCID: PMC6534387 DOI: 10.1126/sciadv.aat5189] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 04/17/2019] [Indexed: 05/05/2023]
Abstract
One of the most important substances on Earth is water. It is an essential medium for living microorganisms and for many technological and industrial processes. Confining water in an enclosed compartment without manipulating it or by using rigid containers can be very attractive, even more if the container is biocompatible and biodegradable. Here, we propose a water-based bottom-up approach for facile encasing of short-lived water silhouettes by a custom-made adaptive suit. A biocompatible polymer self-assembling with unprecedented degree of freedom over the water surface directly produces a thin membrane. The polymer film could be the external container of a liquid core or a free-standing layer with personalized design. The membranes produced have been characterized in terms of physical properties, morphology and proposed for various applications from nano- to macroscale. The process appears not to harm cells and microorganisms, opening the way to a breakthrough approach for organ-on-chip and lab-in-a-drop experiments.
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Affiliation(s)
- Sara Coppola
- Institute of Applied Sciences and Intelligent Systems “E. Caianiello,” Via Campi Flegrei 34, 80078 Pozzuoli, Italy
| | - Giuseppe Nasti
- Institute of Applied Sciences and Intelligent Systems “E. Caianiello,” Via Campi Flegrei 34, 80078 Pozzuoli, Italy
| | - Veronica Vespini
- Institute of Applied Sciences and Intelligent Systems “E. Caianiello,” Via Campi Flegrei 34, 80078 Pozzuoli, Italy
| | - Laura Mecozzi
- Institute of Applied Sciences and Intelligent Systems “E. Caianiello,” Via Campi Flegrei 34, 80078 Pozzuoli, Italy
| | - Rachele Castaldo
- Institute for Polymers, Composites and Biomaterials, CNR, Via Campi Flegrei 34, 80078 Pozzuoli, Italy
| | - Gennaro Gentile
- Institute for Polymers, Composites and Biomaterials, CNR, Via Campi Flegrei 34, 80078 Pozzuoli, Italy
| | - Maurizio Ventre
- Department of Chemical, Materials and Industrial Production Engineering, University of Naples Federico II, Piazzale Tecchio 80, 80125 Naples, Italy
| | - Paolo A. Netti
- Department of Chemical, Materials and Industrial Production Engineering, University of Naples Federico II, Piazzale Tecchio 80, 80125 Naples, Italy
- Center for Advanced Biomaterials For Healthcare @CRIB, Istituto Italiano di Tecnologia, Largo Barsanti e Matteucci 53, 80125 Naples, Italy
| | - Pietro Ferraro
- Institute of Applied Sciences and Intelligent Systems “E. Caianiello,” Via Campi Flegrei 34, 80078 Pozzuoli, Italy
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Russo P, Nasti G, Coppola S, Gentile G, Tuccitto N, Li-Destri G, Marletta G, Ferraro P. Single fibres of pyro-electrospinned PVDF-HFP/MWCNT unveal high electrical conductivity. POLYMER 2018. [DOI: 10.1016/j.polymer.2018.11.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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20
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Mi S, Du Z, Xu Y, Sun W. The crossing and integration between microfluidic technology and 3D printing for organ-on-chips. J Mater Chem B 2018; 6:6191-6206. [PMID: 32254609 DOI: 10.1039/c8tb01661e] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Organ-on-chips were designed to simulate the real tissue or organ microenvironment by precise control of the cells, the extracellular matrix and other micro-environmental factors to clarify physiological or pathological mechanisms. The organ chip is mainly based on the poly(dimethylsiloxane) (PDMS) microfluidic devices, whereas the conventional soft lithography requires a cumbersome manufacturing process, and the complex on-chip tissue or organ chip also depends on the complicated loading process of the cells and biomaterials. 3D printing can efficiently design and automatically print micrometre-scale devices, while bio-printing can also precisely manipulate cells and biomaterials to create complex organ or tissue structures. In recent years, the popularization of 3D printing has provided more possibilities for its application to 3D printed organ-on-chips. The combination of 3D printing and microfluidic technology in organ-on-chips provides a more efficient choice for building complex flow channels or chambers, as well as the ability to create biological structures with a 3D cell distribution, heterogeneity and tissue-specific function. The fabrication of complex, heterogeneous 3D printable biomaterials based on microfluidics also provides new assistance for building complex organ-on-chips. Here, we discuss the recent advances and potential applications of 3D printing in combination with microfluidics to organ-on-chips and provide outlooks on the integration of the two technologies in building efficient, automated, modularly integrated, and customizable organ-on-chips.
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Affiliation(s)
- Shengli Mi
- Biomanufacturing Engineering Laboratory, Advanced Manufacturing Division, Graduate School at Shenzhen, Tsinghua University, Shenzhen, P. R. China.
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21
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Electrohydrodynamic Direct-Writing Micropatterns with Assisted Airflow. MICROMACHINES 2018; 9:mi9090456. [PMID: 30424389 PMCID: PMC6187393 DOI: 10.3390/mi9090456] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 09/06/2018] [Accepted: 09/10/2018] [Indexed: 11/16/2022]
Abstract
Electrohydrodynamic direct-writing (EDW) is a developing technology for high-resolution printing. How to decrease the line width and improve the deposition accuracy of direct-written patterns has been the key to the promotion for the further application of EDW. In this paper, an airflow-assisted spinneret for electrohydrodynamic direct-writing was designed. An assisted laminar airflow was introduced to the EDW process, which provided an additional stretching and constraining force on the jet to reduce the surrounding interferences and enhance jet stability. The flow field and the electric field around the spinneret were simulated to direct the structure design of the airflow-assisted spinneret. Then, a series of experiments were conducted, and the results verified the spinneret design and demonstrated a stable ejection of jet in the EDW process. With assisted airflow, the uniformity of printed patterns and the deposition position accuracy of a charged jet can be improved. Complex patterns with positioning errors of less than 5% have been printed and characterized, which provide an effective way to promote the integration of micro/nanosystems.
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Ye D, Ding Y, Duan Y, Su J, Yin Z, Huang YA. Large-Scale Direct-Writing of Aligned Nanofibers for Flexible Electronics. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2018; 14:e1703521. [PMID: 29473336 DOI: 10.1002/smll.201703521] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 12/08/2017] [Indexed: 05/27/2023]
Abstract
Nanofibers/nanowires usually exhibit exceptionally low flexural rigidities and remarkable tolerance against mechanical bending, showing superior advantages in flexible electronics applications. Electrospinning is regarded as a powerful process for this 1D nanostructure; however, it can only be able to produce chaotic fibers that are incompatible with the well-patterned microstructures in flexible electronics. Electro-hydrodynamic (EHD) direct-writing technology enables large-scale deposition of highly aligned nanofibers in an additive, noncontact, real-time adjustment, and individual control manner on rigid or flexible, planar or curved substrates, making it rather attractive in the fabrication of flexible electronics. In this Review, the ground-breaking research progress in the field of EHD direct-writing technology is summarized, including a brief chronology of EHD direct-writing techniques, basic principles and alignment strategies, and applications in flexible electronics. Finally, future prospects are suggested to advance flexible electronics based on orderly arranged EHD direct-written fibers. This technology overcomes the limitations of the resolution of fabrication and viscosity of ink of conventional inkjet printing, and represents major advances in manufacturing of flexible electronics.
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Affiliation(s)
- Dong Ye
- State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
- Flexible Electronics Research Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Yajiang Ding
- State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
- Flexible Electronics Research Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Yongqing Duan
- State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
- Flexible Electronics Research Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Jiangtao Su
- State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
- Flexible Electronics Research Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Zhouping Yin
- State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
- Flexible Electronics Research Center, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Yong An Huang
- State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
- Flexible Electronics Research Center, Huazhong University of Science and Technology, Wuhan, 430074, China
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23
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Mei X, Chen Q, Wang S, Wang W, Wu D, Sun D. The microscale Weissenberg effect for high-viscosity solution pumping at the picoliter level. NANOSCALE 2018; 10:7127-7137. [PMID: 29616244 DOI: 10.1039/c7nr09315b] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Transportation of highly viscous solutions at the picoliter level with a rapid dynamic response is paramount for micro/nano-fabrication. With the advantages of a higher length-wall (thickness) ratio and a more stable free surface compared to those of the traditional Weissenberg effect (TWE), the microscale Weissenberg effect (MWE) can continuously and controllably pump high-viscosity solutions at the picoliter scale. Some typical characteristics and behaviors of MWE are investigated as the rotation rod diameter decreases to the microscale of ∼100 μm. The pumped minimum solution volume can reach 167.5 pL per second, and the minimum response time of solution pumping is 0.3 s, which is much shorter than that of pressure driven pumping. Then, a new direct writing with an adjustable jet diameter based on the MWE is proposed to write microstructures on a substrate from a solution with a viscosity of approximately 130.1 Pa s. The stability of the as-spun jet and the deposited structures is improved when a high voltage is applied. To fully demonstrate the advantages of MWE, MWE-based direct writing is performed to successfully fabricate microfluidic channels with variable diameters. Thus, the system can overcome the problems of high transport resistance to the pumping of a high-viscosity solution.
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Affiliation(s)
- Xuecui Mei
- Department of Mechanical and Electrical Engineering, Xiamen University, Xiamen 361000, P. R. China.
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Chen Q, Mei X, Shen Z, Wu D, Zhao Y, Wang L, Chen X, He G, Yu Z, Fang K, Sun D. Direct write micro/nano optical fibers by near-field melt electrospinning. OPTICS LETTERS 2017; 42:5106-5109. [PMID: 29240148 DOI: 10.1364/ol.42.005106] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 11/09/2017] [Indexed: 06/07/2023]
Abstract
A simple fabrication method of micro/nano-optical fibers (MNOFs) based on near-field melt electrospinning (NMES) is proposed in this Letter. Single fibers with diameters ranging from 500 nm to 6 μm were directly written by near-field electrospinning of molten poly(methyl methacrylate) (PMMA). The morphology and transmission characteristics of single PMMA MNOFs were experimentally measured. The results showed that PMMA MNOFs have the advantages of smooth surfaces, uniform diameters, and low loss. As an example of one-step fabrication for MNOF devices, a planar helical MNOF structure was directly written and optically characterized. To demonstrate the versatility of the NMES process, in combination with the microfluidic technique, a liquid refractive index-sensing chip was fabricated and tested. Our results demonstrate that the proposed fabrication method has strong potential in the direct writing of patterned optical devices and heterogeneous integrated devices.
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25
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Influences of Excitation on Dynamic Characteristics of Piezoelectric Micro-Jets. MICROMACHINES 2017; 8:mi8070213. [PMID: 30400404 PMCID: PMC6190458 DOI: 10.3390/mi8070213] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 06/14/2017] [Accepted: 06/30/2017] [Indexed: 11/24/2022]
Abstract
Piezoelectric micro-jets are based on piezoelectric ink-jet technology and can achieve the drop-on demand requirements. A piezoelectric micro-jet which is designed for bearing lubrication is presented in this paper. In order to analyze the fluid dynamic characteristics of the piezoelectric micro-jet so as to obtain good injection performance, a direct coupling simulation method is proposed in this paper. The effects of inlet and viscous losses in the cavity are taken into account, which are close to the actual conditions in the direct coupling method. The effects of the pulse excitation parameters on the pinch-off time, tail length, velocity, and volume of the droplet are analyzed by the proposed direct coupling method. The pressure distribution inside the cavity of the micro-jet and the status of the droplet formation at different times are also given. In addition, the method is proved to be effective in predicting and analyzing the fluid dynamic characteristics of piezoelectric micro-jets by comparing the simulation results with the experimental results.
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