Remote excitation and readout of a high Q silicon resonator

This paper presents the first published report of a totally passively driven actuation and readout of an electromechanical resonator using inductive coupling. The goal of this work is to remotely excite and read a MEMS comb drive resonator with a focus on low power operation while simultaneously maximizing standoff distance without the use of active electronics at the sensor location. Initial measurements focused on the determining the relationship of the received signal level with the drive parameters. Reading the resonator through integrated piezoresistors, the drive response showed the expected dependence of both the RF power and AM modulation depth and the coil separation matched a simple model of a 6 cm coil radius and B⁴ dependence. Measurements of an entirely wireless (read and driven) resonator were made to explore the standoff capability with a practical limit of ~15 dBm RF power to both the drive and receive systems. A standoff of 9 cm was demonstrated limited by power input to the device. The effect of read and drive coil position was also studied.