Stiction-free poly-SiGe resonators for monolithic integration of biosensors with CMOS

This work presents the first fabricated and characterized MEMS in polycrystalline silicon-germanium (poly-SiGe) for biosensing applications. The devices, clamped-clamped microresonators, combine the possibility of above-IC MEMS-CMOS integration with a stiction-free design that enables biomolecule mass sensing in air. By perforating the resonant beam with square or hexagonal holes, a higher surface-to-volume ratio is achieved leading to an increased relative frequency shift for a certain analyte surface density. A minimum detectable mass of ~2pg in air was calculated. A mass sensing test was performed on these perforated devices by immobilization of biotin and the extraction of the resulting resonance frequency shift.