Modeling and optical testing of viscous-driven microcantilevers for acoustic particle velocity sensing

Compared to traditional sound detection based on pressure sensing, bioinspired vector acoustic sensing using viscous-driven microstructures offers intrinsic advantages for source localization, directional detection, and noise suppression. However, the relationship between design parameters and noise performance in these mechanical sensing structures remains insufficiently understood. In this work, we develop a simplified single-degree-of-freedom lumped model to describe both thermomechanical noise and sound-induced motion of viscous-driven microbeams. The model agrees well with experimental results across a range of beam geometries measured using laser Doppler vibrometry. It further reveals that increasing structural damping, typically avoided in pressure sensors, can lower the noise floor in viscous-driven structures. This insight highlights a new design strategy for high-performanceparticle velocity sensors.