Piezoelectric Transduction of a Button-like Mode Disk Resonator for Enhanced Quality Factor in Water

We present a unique lateral bulk resonance mode with a lateral strain profile that resembles a shirt button that we transduce piezoelectrically in a MEMS disk resonator. This button-like (BL) mode offers the 3-fold benefits of (1) intrinsic feedthrough cancellation using fully-differential transduction, (2) strong piezoelectric coupling from the associated strain profile, and (3) higher quality (Q) factor compared to the fundamental wine glass (WG1) mode in water. These above features make the BL mode highly attractive when applying MEMS resonators to mass sensing in liquid. We demonstrate enhancements in Q factor by 68% to a Q factor of 265 and 41% increase in the coupling factor (k(t)(2)) relative to the WG1 mode when transducing in water, leading to a signal-to-background ratio (SBR) of 28.1 dB even in water.