High Power Si Sidewall Heaters for Fluidic Applications Fabricated by Trench-Assisted Surface Channel Technology

We have fabricated mechanically stable, thermally isolated microfluidic channels with silicon heaters embedded in the sidewalls, using the trench-assisted surface channel technology (TASCT) [1]. Sidewall heating results in an enhanced heating uniformity while allowing high heating powers because of the relatively large cross-sectional area ( 20 μm by 50 μm) of the silicon heaters. In the proof-of-principle device a maximum temperature of 406 °C was reached at a heating power of 1.4 W, limited by thermal expansion of the channel. The fabrication process enables both the channels and the silicon heaters to have a rectangular cross-section with a depth defined by the device layer thickness and a variable width and length.