Highly-doped bulk silicon microheaters and electrodes embedded between free-hanging microfluidic channels by surface channel technology

Surface Channel Technology is widely used as the fabrication process to make free-hanging microchannels in various microfluidic devices. In this extended abstract, we report an innovative fabrication method to embed highly-doped silicon electrodes between the adjacent free-hanging microfluidic channels using the SCT process. Essentially, two parameters are used to tune the final cross-sectional geometry and size of the bulk silicon electrodes. One is the distance between two adjacent rows of slits and the other is the width of flat membrane above the microchannels. The advantageous physical features make bulk silicon electrodes suitable for many sensing and actuation applications. When the bulk silicon electrodes are used as microheaters, they allow higher power dissipation. This is because of their larger cross-sectional areas compared to the commonly used thin film metal microheaters. Moreover, as sensing electrodes, bulk silicon electrodes are located between the sidewalls of two adjacent microchannels. This makes them applicable as the sidewall resistive or capacitive readout in e.g. flow sensors.