Fig. 2: Fabrication process flow of the microfluidic device.

a Photoresist casting on a silicon dioxide-coated wafer. b Maskless lithography for channel design. c SiO2 etching, d resist stripping, e second lithography to open the inlet–outlet and pressure ports. f DRIE for Si etching. g Photoresist stripping. h Ti and Al coating to protect the wafer as well as etching and second DRIE for etching through the wafer to open inlets, outlets, and pressure ports. i Wet etching of Al. j Wet etching of Ti. k Wet etching of SiO2. l Anodic bonding of the substrate to glass after etching the silicon dioxide layer completely.