A Multichannel Electroosmotic Flow Pump Using Liquid Metal Electrodes
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Original Article
A Multichannel Electroosmotic Flow Pump Using Liquid Metal Electrodes Yongchang Zheng
1,†
, Kai Kang
1,†
, Fucun Xie
1
, Hanyu Li
1
& Meng Gao
2,
*
Received: 24 January, 2019 / Accepted: 3 May, 2019 / Published online: 29 August, 2019 ⒸThe Korean BioChip Society and Springer 2019
Abstract Injecting a room-temperature liquid metal into microchannels offers a simple, rapid, and lowcost method of fabricating microfluidic electrodes. In this work, these electrodes are used to develop a multichannel electroosmotic flow pump for high-flow-rate microfluidic bio analysis applications. In this pump, two identical square-wave shaped liquid metal electrodes were located at both ends of pumping channels on the same horizontal level, and were separated by polydimethylsiloxane gaps from the pumping channels. To test the pumping performance, fluorescent particles were diluted with deionized water and injected into the pumping channels to measure the flow velocity. The results show that the pump with five parallel pumping channels can drive water at a speed of 4.63–45.76 μm/s with applied voltage of 300–1000 V, when the pumping channels are 30 μm wide, 50 μm high, and 250 μm long with 30-μm polydimethylsiloxane gaps. It can reach its highest possible flow rate of 325 nl/min when the applied voltage reaches its limit 3900V (150 μm long pumping channels, 150 μm long nonpumping channels and 30 μm PDMS gap with 10 parallel pumping channels). This EOF pump should be potential in many high-flow-rate microfluidic applications.
1 Department of Liver Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, 100730 Beijing, P. R. China 2 Research Center for Internet of Things, Advanced Institute of Information Technology, Peking University, 311215, Hangzhou, Zhejiang, P. R. China † These authors contrilbuted equally. *Correspondence and requests for materials should be addressed to Meng Gao ( [email protected])
Keywords: Electroosmotic flow pump, Liquid metal electrodes, Microfluidics
Introduction Electroosmotic flow pumps have recently received increasing attentions due to their capabilities of driving a wide range of liquids, controlling small-volume fluids and its flow rates, as well as generating high pumping pressures1-9. In biochip applications, they can drive bio samples with nondestructive and uniformly stable flows under fast and easy operation. Normally, noble metals (platinum, gold, etc.) are used to fabricate microelectrodes of electroosmotic flow pumps1,5-7. By modulating the electric field intensity and direction of microelectrodes, these pumps can easily drive bidirectional fluid flows under direct current (DC) electric field. Unfortunately, these electrodes are directly exposed inside fluids, leading to electrolysis on the surface and undesired failures, such as bubble formation, corrosion, and Joule heating, which eventually limit the fluid flow5,7. Alternating current (AC) electric field can decrease the electrolysis and bub
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