A simple method to implement and further performances enhancement of the shear force sensor

This study reports a simple method to design the shear force sensor using the SOI wafer with polymer filler (PDMS). The shear force sensor contains three sensing units: two cantilevers with piezo-resistors are the sensing units to detect shear force in two orthogonal directions and the central membrane with piezo-resistors is the sensing unit to monitor the normal load. The polymer filler serves as the interface layer for force transmission and the protection layer for suspended sensing units. The performance of the shear force sensor can be improved by varying the cavity size of sensing cantilevers. Measurements indicate that the sensitivity increases for 4-fold (from 0.039%/kPa to 0.17%/kPa) as the cavity size W
_cavity
×L
_cavity
increases from 300μm×550μm to 700μm×1350μm. This study provides a simple approach to both the design and process to change performances of the shear force sensor.