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Feng H, Shen S, Jin M, Zhang Q, Liu M, Wu Z, Chen J, Yi Z, Zhou G, Shui L. Microwell Confined Electro-Coalescence for Rapid Formation of High-Throughput Droplet Array. Small 2023; 19:e2302998. [PMID: 37449335 DOI: 10.1002/smll.202302998] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 06/14/2023] [Indexed: 07/18/2023]
Abstract
Droplet array is widely applied in single cell analysis, drug screening, protein crystallization, etc. This work proposes and validates a method for rapid formation of uniform droplet array based on microwell confined droplets electro-coalescence of screen-printed emulsion droplets, namely electro-coalescence droplet array (ECDA). The electro-coalescence of droplets is according to the polarization induced electrostatic and dielectrophoretic forces, and the dielectrowetting effect. The photolithographically fabricated microwells are highly regular and reproducible, ensuring identical volume and physical confinement to achieve uniform droplet array, and meanwhile the microwell isolation protects the paired water droplets from further fusion and broadens its feasibility to different fluidic systems. Under optimized conditions, a droplet array with an average diameter of 85 µm and a throughput of 106 in a 10 cm × 10 cm chip can be achieved within 5 s at 120 Vpp and 50 kHz. This ECDA chip is validated for various microwell geometries and functional materials. The optimized ECDA are successfully applied for digital viable bacteria counting, showing comparable results to the plate culture counting. Such an ECDA chip, as a digitizable and high-throughput platform, presents excellent potential for high-throughput screening, analysis, absolute quantification, etc.
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Affiliation(s)
- Haoqiang Feng
- International Joint Laboratory of Optofluidic Technology and System, National Centre for International Research on Green Optoelectronics, South China Academy of Advanced Optoelectronics & School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou, 510006, P. R. China
| | - Shitao Shen
- International Joint Laboratory of Optofluidic Technology and System, National Centre for International Research on Green Optoelectronics, South China Academy of Advanced Optoelectronics & School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou, 510006, P. R. China
| | - Mingliang Jin
- International Joint Laboratory of Optofluidic Technology and System, National Centre for International Research on Green Optoelectronics, South China Academy of Advanced Optoelectronics & School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou, 510006, P. R. China
| | - Qilin Zhang
- International Joint Laboratory of Optofluidic Technology and System, National Centre for International Research on Green Optoelectronics, South China Academy of Advanced Optoelectronics & School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou, 510006, P. R. China
| | - Mengjun Liu
- International Joint Laboratory of Optofluidic Technology and System, National Centre for International Research on Green Optoelectronics, South China Academy of Advanced Optoelectronics & School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou, 510006, P. R. China
| | - Zihao Wu
- International Joint Laboratory of Optofluidic Technology and System, National Centre for International Research on Green Optoelectronics, South China Academy of Advanced Optoelectronics & School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou, 510006, P. R. China
| | - Jiamei Chen
- International Joint Laboratory of Optofluidic Technology and System, National Centre for International Research on Green Optoelectronics, South China Academy of Advanced Optoelectronics & School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou, 510006, P. R. China
- Shenzhen Bao'an District Traditional Chinese Medicine Hospital, Shenzhen, 518133, P. R. China
| | - Zichuan Yi
- College of Electron and Information, University of Electronic Science and Technology of China, Zhongshan Institute, Zhongshan, 528402, P. R. China
| | - Guofu Zhou
- International Joint Laboratory of Optofluidic Technology and System, National Centre for International Research on Green Optoelectronics, South China Academy of Advanced Optoelectronics & School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou, 510006, P. R. China
| | - Lingling Shui
- International Joint Laboratory of Optofluidic Technology and System, National Centre for International Research on Green Optoelectronics, South China Academy of Advanced Optoelectronics & School of Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou, 510006, P. R. China
- Guangdong Provincial Key Laboratory of Nanophotonic Functional Materials and Devices, South China Normal University, Guangzhou, 510006, P. R. China
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Li S, Yuan S, Zhang Y, Guo H, Liu S, Wang D, Wang Y. Molecular Dynamics Study on the Demulsification Mechanism of Water-In-Oil Emulsion with SDS Surfactant under a DC Electric Field. Langmuir 2022; 38:12717-12730. [PMID: 36197725 DOI: 10.1021/acs.langmuir.2c02364] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Application of an electric field is an effective demulsification method for water-in-oil (W/O) emulsions. For the W/O emulsions stabilized by anionic surfactants, the microscopic demulsification mechanism is still not very clear. In this work, the coalescence behavior of two droplets stabilized by the anionic surfactant sodium dodecyl sulfate (SDS) in the oil phase under a DC electric field is investigated by molecular dynamics simulation. The effects of electric field strength and oil type on the electrocoalescence of two water droplets are mainly considered. The trajectory snapshots and center of mass of the two water droplets suggest that there is almost no migratory coalescence. The movement of sodium ions and SDS, which is a combined effect of the electric field force and the resistance from the oil phase, is crucial for the deformation and connection of two water droplets. The results of mean square displacement, radial distribution function, hydration number, and interaction energies of Na+-H2O and SDS-H2O indicate that the sodium ion has a stronger ability to carry water molecules for movement than SDS. The stronger electric field strength will result in more severe deformation and shorter coalescence time. Under the higher electric field strength, the two droplets will be elongated into a slender water ribbon. By applying a pulsed DC electric field with suitable amplitude, frequency, and duty ratio, it is possible to achieve full coalescence for the ionic surfactant-stabilized W/O emulsions. The oil phase also plays an important role for the deformation of droplets and the migration of emulsion components. For the different oil phases, a longer time or stronger electric field strength would be needed for the electrocoalescence of droplets in the oil phase with higher density and viscosity. Our results are expected to be helpful for practical application in the petroleum industry and chemical engineering.
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Affiliation(s)
- Shiyan Li
- College of Science, China University of Petroleum, Qingdao266580, China
| | - Shundong Yuan
- College of Science, China University of Petroleum, Qingdao266580, China
| | - Yuanwu Zhang
- College of Science, China University of Petroleum, Qingdao266580, China
| | - Huiying Guo
- Research Institute of Experiment and Detection, Xinjiang Oilfield Company, PetroChina, Karamay834000, China
| | - Sai Liu
- Research Institute of Experiment and Detection, Xinjiang Oilfield Company, PetroChina, Karamay834000, China
| | - Diansheng Wang
- College of Science, China University of Petroleum, Qingdao266580, China
| | - Yudou Wang
- College of Science, China University of Petroleum, Qingdao266580, China
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Zhao Y, Gu Y, Gao G. Piezoelectricity induced by pulsed hydraulic pressure enables in situ membrane demulsification and oil/water separation. Water Res 2022; 215:118245. [PMID: 35290871 DOI: 10.1016/j.watres.2022.118245] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 02/23/2022] [Accepted: 03/01/2022] [Indexed: 05/25/2023]
Abstract
Recovering oil from oily wastewater is not only for economic gains but also for mitigating environmental pollution. However, demulsification of oil droplets stabilized with surfactants is challenging because of their low surface energy. Although the widely used oil/water separation membrane technologies based on size screening have attracted considerable attention in the past few decades, they are incapable of demulsification of stabilized oil emulsions and the membrane concentrates often require post-processing. Herein, the piezoelectric ceramic membrane (PCM), which can respond to the inherent transmembrane pressure in the pressure-driven membrane processes, was employed to transform hydraulic pressure pulses into electroactive responses to in situ demulsification. The pulsed transmembrane pressure on the PCM results in the generation of considerable rapid voltage oscillations over 3.2 V and a locally high electric field intensity of 7.2 × 107 V/m, which is capable of electrocoalescence with no additional stimuli or high voltage devices. Negative dielectrophoresis (DEP) force occurred in this membrane process and repelled the large size of oil after demulsification away from the PCM surface, ensuring continuous membrane demulsification and oil/water separation. Overall, PCM provides a further opportunity to develop an environmentally friendly and energy-saving electroresponsive membrane technology for practical applications in wastewater treatment.
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Affiliation(s)
- Yang Zhao
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China
| | - Yuna Gu
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China
| | - Guandao Gao
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China; Research Center for Environmental Nanotechnology (ReCENT), Nanjing University, Nanjing 210023, China.
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