Multi-Axis Large-Range Silicon-Micromachined Force Sensing System

This paper reports the first microfabricated modular multi-degree-of-freedom (DOF) force sensing system using a p+ silicon and glass wafer stack. The proposed 2-DOF sensor combines a large measurement range and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{small} \ 2\times 2 \ \text{mm}^{2}$</tex> active region with the use of common and off-the-shelf substrates. The four mask fabrication method entails dry-etching of electrodes and 300 µm high micro-pillars into bulk silicon, which are anodically bonded to a glass wafer containing micromachined cavities with gold electrodes. Four 2-DOF sensor elements can be assembled in a single package to allow for larger-range 6-DOF force/torque sensing functionality. The sensor was characterized for 0–15 N in normal direction and 0-2.5 N in shear direction, showing relatively high sensitivities for the sensor size due to the dense electrode array.