Polydimethylsiloxane–LiNbO3 surface acoustic wave micropump devices for fluid control into microchannels

Abstract

This paper presents prototypical microfluidic devices made by hybrid microchannels based on piezoelectric LiNbO₃ and polydimethylsiloxane. This system enables withdrawing micropumping by acoustic radiation in microchannels. The withdrawing configuration, integrated on chip, is here quantitatively investigated for the first time, and found to be related to the formation and coalescence dynamics of droplets within the microchannel, primed by surface acoustic waves. The growth dynamics of droplets is governed by the water diffusion on LiNbO₃, determining the advancement of the fluid front. Observed velocities are up to 2.6 mm s⁻¹ for 30 dBm signals applied to the interdigital transducer, corresponding to tens of nl s⁻¹, and the micropumping dynamics is described by a model taking into account an acoustic power exponentially decaying upon travelling along the microchannel. This straighforward and flexible micropumping approach is particularly promising for the withdrawing of liquids in lab-on-chip devices performing cycling transport of fluids and biochemical reactions.