A novel bionic dual-stiffness piezoresistive millimeter-sized cantilever

Abstract Millimeter-sized cantilevers are a common structure in sensors. Inspired by whisker structures, we proposed a novel bionic dual-stiffness piezoresistive millimeter-sized cantilever (DPMC) to enhance cantilever performance. The DPMC incorporates a backside rectangular recess at the root of the cantilever and a flat upper surface. An etching technology using a controllable area shadow mask was proposed to fabricate a locally rectangular recess on the piezoresistor’s backside in the cantilever’s root. Three piezoresistive millimeter-sized cantilevers (PMCs), each with a width of 500 μ m, were fabricated. These cantilevers featured piezoresistive sensing section thicknesses of 6.2 μ m, 10 μ m, and 10 μ m, and transmission section lengths of 4500 μ m, 4500 μ m, and 7500 μ m, respectively. Scanning Electron Microscopy (SEM) images confirm the feasibility and controllability of fabricating rectangular backside recesses using the shadow mask backside etching method. Experimental results demonstrated that the DPMC achieved an extended upper detection limit of about 16% while maintaining comparable sensitivity to a uniform PMC with a transmission section length of 7500 μ m under low uniform pressure. This cantilever introduces a novel approach for achieving both high sensitivity and a high upper detection limit in PMCs.