A facile method for the fabrication of glass-PDMS-glass sandwich microfluidic devices by sacrificial molding

The microfluidic devices with a glass-PDMS-glass (G-P-G) sandwich configuration are of interest for a wide range of applications. However, it remains a challenge to fabricate the G-P-G sandwich microfluidic devices due to difficulties in demolding and transferring the fragile PDMS thin-film microstructures. Here, we present a novel strategy to fabricate glass-PDMS-glass (G-P-G) microfluidic devices by embedding a water-soluble, sacrificial mold in sandwiched PDMS film. Firstly, a caramel mold is patterned on a glass slide by degassing-assisted microfluidic soft lithography. Then a thin layer of liquid PDMS is directly cast onto the caramel mold and pressed by another glass slide to form a sandwich structure. Finally, the caramel mold is dissolved by immersing the G-P-G sandwich construction in hot water, leaving a desired microchannel network in sandwich construction. Benefitting from sacrificial molding, this method can easily produce the G-P-G microfluidic devices without demolding, transferring, bonding or assembling fragile PDMS thin-film microstructures, making G-P-G microdevices more accessible to a broader researchers. We also illustrate its applicability in constructing low-evaporation microfluidic devices.