Tibrewala, A.; Phataralaoha, A.; Büttgenbach, S. (Institute for Microtechnology, Technical University of Braunschweig, Germany)
3D force sensors were successfully fabricated using bulk silicon micromachining. p-diffused piezoresistors were integrated in the membrane structure and the membranes were etched in KOH. To lower the horizontal to vertical stiffness ratio (Sx/Sz), five boss full membrane were developed, along with traditional one boss full membrane. FEM simulations were performed to locate the high stress point on the membranes, where piezoresistors were then placed. Vertical and horizontal sensitivities, stiffness ratios, maximum deflection of the sensors were measured for both the designs.