Abstract
Injection of liquid metal into a polydimethylsiloxane (PDMS) channel can provide a simple, cheap, and fast method to fabricate a noncontact electrode for micro electroosmotic flow (EOF) pumps. In this study, a multi-stage EOF pump using liquid metal noncontact electrodes was proposed and demonstrated for high-flow-velocity applications. To test the pumping performance of this EOF pump and measure the flow velocity, fluorescent particles were added into deionized (DI) water to trace the flow. According to the experimental results, the pump with a five-stage design can drive a water flow of 5.57 μm/s at 10 V, while the PDMS gap between the electrode and the pumping channel is 20 μm. To provide the guidance for the pump design, parametric studies were performed and fully discussed, such as the PDMS gap, pumping channel dimension, and stage number. This multi-stage EOF pump shows potential for many high-flow-velocity microfluidic applications.
Highlights
Electroosmotic flow (EOF) pumps have become attractive for a wide range of applications, including microfluidic actuation [1,2], biochemical analysis [3,4,5,6], and electronic cooling [7,8]
Due to the outstanding electrical and mechanical properties, liquid metal has been considered as a promising material to fabricate noncontact electrodes in microfluidics [24].The liquid metal is a kind of gallium-based alloy whose melting point is around room temperature
In our previous work [27], we proposed a handy single-channel EOF pump using this liquid metal noncontact electrode
Summary
Electroosmotic flow (EOF) pumps have become attractive for a wide range of applications, including microfluidic actuation [1,2], biochemical analysis [3,4,5,6], and electronic cooling [7,8]. Polyacrylamide-filled capillary [17,18], Nafion-coated Ag/Ag2O [19,20], alizarin paste-coated carbon paper [21,22], and polyaniline-wrapped aminated graphene [23] have been reported to fabricate noncontact electrodes for EOF pumps These noncontact electrodes can enable stable and efficient pumping performance for a long time. Due to the outstanding electrical and mechanical properties, liquid metal has been considered as a promising material to fabricate noncontact electrodes in microfluidics [24].The liquid metal is a kind of gallium-based alloy whose melting point is around room temperature It can be and quickly injected into polydimethylsiloxane (PDMS) microchannels to form stable electrodes in any shape, at any location, because of its advantageous properties, including good flowability, deformability, low viscosity, and excellent wettability with PDMS [24,25,26]. A multi-stage EOF pump (shown in Figure 1) using the liquid metal noncontact electrode was developed for high-flow-rate microfluidic applications. I2n0tμhmis phuigmh.pI,nththeiPsDpMumSpg,atphebePtDwMeeSngaadpjabceetnwt etwenoapdujamcepnint gtwchoapnunmelpsihnagscthhaensnaemlsehsaizsethaes tshaemwe isdizthe aosf tthhee pwuidmtphionfgtchheapnunmel.ping channel
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