A coplanar microfluidic channel applied for surface modification of oxidized Galinstan

In this paper, a gas permeable PDMS (polydimethlysiloxane) based microfluidic device has been reported for surface modification of oxidized Galinstan. A microchannel with Galinstan droplets was surrounded by another coplanar channel filled with HCl solution. Due to the excellent permeability of PDMS, the HCl vapor easily passed through a thin PDMS wall between two channels (interchannel wall) to achieve continuous chemical reaction with oxidized Galinstan. The PDMS wall thickness was optimized after studying the recovery of non-wetting characteristics of HCl treated Galinstan droplet and HCl permeability through different thickness of PDMS films. The novel microfuidic device was fabricated using conventional micro-molding technology. The Lab VIEW controlled syringe pump system was used for characterizing behavior of HCl vapor treated Galinstan in the microchannel. The experimental results demonstrated that the method easily removes the oxide layer of oxidized Galinstan and can effectively move HCl-treated Galinstan droplets in microchannel.