Compensation of the anisotropic behavior of single crystalline silicon in a 3D tactile sensor

Abstract

Single crystalline silicon is often used as a base material for micro electromechanical systems (MEMS). A disadvantage from a mechanical point of view is its anisotropic mechanical behavior. A suspension with deformable structures in different crystallographic orientations therefore leads to an unfavorable anisotropic mechanical behavior of the device. To create an isotropic suspension stiffness, the design is limited to deformable structures in equivalent crystallographic orientations, which limits the design possibilities. This paper presents a method to compensate for the anisotropic mechanical properties of silicon by adjusting the dimensions of the mechanical suspension. The method is investigated by the example of a 3D tactile sensor, developed at the Eindhoven University of Technology. Using experimental results and Finite Element Analysis it is shown that an isotropic stiffness can be obtained. As a result, the measurement range and uncertainty of the sensor within this range are improved by a factor of 4. The method is applicable to all systems with an anisotropic mechanical behavior of its material.