Fabrication of a Hydrophilic Poly(dimethylsiloxane) Microporous Structure and Its Application to Portable Microfluidic Pump

Abstract

In this paper, we present a simple and low-cost fabrication technique of a novel hydrophilic poly(dimethylsiloxane) (PDMS) microporous structure (or microsponge) based on a modified sugar leaching technique. A surfactant, Silwet L-77 enabled us to achieve the wettability conversion of PDMS from hydrophobic to hydrophilic. The wettability changes of PDMS surfaces and microsponges were characterized at various weight percentages of Silwet L-77 and it was found that a hydrophilic PDMS microsponge containing 0.6% of Silwet L-77 rapidly absorbed water droplets. The average porosity of the fabricated PDMS microsponges was measured as 0.55. We have successfully demonstrated the hydrophilic PDMS microsponge as a portable pump for a microfluidic device. The hydrophilic PDMS microsponge was firmly bonded at the inlet of a PDMS microchannel via oxygen plasma treatment. A water-phase sample was easily loaded into the hydrophilic PDMS microsponge and it was released and injected into the microchannel by simply pushing the microsponge.