Stress-Amplified Piezoelectric MEMS Microphone with Concave-Convex Rings

This paper presents a clamped piezoelectric MEMS microphone with a segmented piezoelectric layer of alternating thickness. A periodic concave-convex structure is introduced in the proximity of the fixed boundary, where concave rings contain a single piezoelectric layer and convex rings consist of two layers. This modified bimorph configuration yields higher stress and broader high-stress regions under actuation than conventional unimorph or bimorph designs. This results in enhanced sensitivity through series-parallel interconnection. The resonant frequency and sensitivity can be tuned by varying the number and size of the corrugations. Finite element simulations have demonstrated a 43.17% enhancement in sensitivity and a resonant frequency of 28.9 kHz, which is 3.69 kHz lower than that of a standard bimorph, with a 1 kHz sensitivity of –61.29 dB (ref. 1 V/Pa). The design demonstrates strong potential for compact, low-power acoustic sensing applications.