Complete filling of liquid metal in comb-shaped transducers for acoustofluidics

Abstract

We demonstrate the complete filling of both deionized water (DI water) and liquid metal (EGaIn) into closed-end microchannels driven by a constant pressure at the inlet. A mathematical model based on gas diffusion through porous PDMS wall is developed to unveil the physical mechanism in the filling process. The proposed theoretical analysis based on our model agrees well with the experimental observations. We also successfully generate traveling surface acoustic waves by actuating interdigitated microchannels filled with EGaIn. Our work will bring significant insights in the fabrication of liquid electrodes for various microfluidic lab-on-a-chip applications.