Flexible tactile sensor for shear stress measurement using transferred sub-μm-thick Si piezoresistive cantilevers

We propose a flexible tactile sensor using sub-mu m-thick Si piezoresistive cantilevers for shear stress detection. The thin Si piezoresistive cantilevers were fabricated on the device layer of a silicon on insulator (SOI) wafer. By using an adhesion-based transfer method, only these thin and fragile cantilevers were transferred from the rigid handling layer of the SOI wafer to the polydimethylsiloxane layer without damage. Because the thin Si cantilevers have high durability of bending, the proposed sensor can be attached to a thin rod-type structure serving as the finger of a robotic hand. The cantilevers were arrayed in orthogonal directions to measure the X and Y directional components of applied shear stresses independently. We evaluated the bending durability of our flexible tactile sensor and confirmed that the sensor can be attached to a rod with a radius of 10 mm. The sensitivity of the flexible tactile sensor attached to a curved surface was 1.7 x 10(-6) Pa-1 on average for a range of shear stresses from -1.8 x 10(3) to 1.8 x 10(3) Pa applied along its surface. It independently detected the X and Y directional components of the applied shear stresses.