Generation of Electromechanical Frequency Combs in Fluid Media with a Parametrically Driven Capacitive Microresonator

Abstract

The generation of electromechanical frequency combs in both air and liquid environments using a capacitive microresonator array is presented in this paper. In contrast to frequency comb generation in purely mechanical resonators, we show that the damping dependent threshold for comb generation can be reduced by parametrically coupling a resonant electrical circuit to the mechanical resonator. A 1-D lumped parameter model of the proposed system is presented and semi-analytical solutions are developed to investigate the parameters influencing frequency comb formation under various operating conditions. The results obtained with numerical simulations are experimentally validated using a commercially available MEM resonator, and frequency combs with a repetition rate sensitive to the force on the mechanical resonator are generated with a single electrical drive in air and in a liquid-filled microfluidic channel. In contrast to prior work on electromechanical frequency combs, this work represents a simple yet robust approach to generating stable combs, thereby enabling its practical use in applications such as gas sensing and microfluidics.