Piezoresistive Sensing in a SOI Mechanically Coupled Micromechanical Multiple-Resonator Array

This paper presents the first results from mechanically coupling multiple resonators in an array in silicon-on-insulator while also employing piezoresistive sensing. By careful design of the couplers, the resonators in the array are synchronized to all resonate in phase and also at the same frequency. By collectively summing the currents from each of the resonators in the array, the net output current is thereby increased. By using piezoresistive sensing, the benefit of arraying is further improved by exploiting the higher electromechanical conversion gain provided by the piezoresistive effect. Further to this enhancement in transduction, our results also show that Q was increased with the coupling. A synchronized array of up to three extensional mode square-plate resonators is demonstrated here, although the concept can be further extended to larger size arrays. We have also formulated a semi-analytical model (with the aid of finite-element analysis) to describe the electromechanical transfer function of the device. Close agreement between our measurements and the model confirms that the observed enhancements afforded by arraying are within theoretical expectations.