Silicon Carbide (Sic) Micromechanical Self-Sustained Oscillator Operating In Liquid

This digest paper reports on the-first experimental demonstration of self-sustained feedback oscillators referenced to silicon carbide (SiC) beam micromechanical resonators operating in liquid, showing greatly enhanced effective quality-factors (Q(eff)) and good frequency stability. With optical excitation, opto-electrical readout and-feedback control, a SiC doubly-clamped beam (dimensions: 100x15x0.5 mu m) is observed to attain self-sustained oscillation at its fundamental flexural mode of similar to 345kHz in water with similar to 700-fold Q improvement. For the first time, frequency stability is quantified in such an in-liquid feedback oscillator, with tau similar to 10(-4) in water for even relatively long averaging time (tau>100s). We also demonstrate the capability of the SiC oscillator for in-liquid microsphere sensing and estimate this oscillator has a mass responsivity of similar to 17.2Hz/pg. Such SiC micromechanical self-sustained oscillators, together with the appealing mechanical, optical properties of SiC [1], plus its biocompatibility [2] and chemical stability in solutions, open new possibilities for real-time biosensing and in-situ monitoring of cells and molecules in liquid.