Enhancement of an indium phosphide resonator sensor microsystem through the development of an adaptive feedback circuit and electrospray deposition

Abstract

Cantilever resonator sensor enhancement through the development of an adaptive feedback circuit and the use of electrospray deposition is presented. The feedback system adapts to a wide range of resonators by implementing a hill climbing algorithm, locking onto the cantilever's resonance condition. Eight different cantilever-based sensors (Length=40-75μm), resonating at 201.0kHz to 592.1kHz, with a minimum standard deviation of 11.8Hz, corresponding to a mass resolution limit of 123fg for the device, have been dynamically detected using a single circuit. Electrospray deposition of thin-films on multiple substrate materials and released microstructures has been performed. An average deposition rate of 9.5±5nm/min was achieved with an average surface roughness of 4.5nm on a 197nm thick film. This technology will enable a post-processing method for depositing absorbing layers for sensing applications. With the development of these two technologies, the practical functionality of a chip-scale sensor microsystem will be more readily realized.