CMOS integrated silicon/glass-bonded 3D force/torque sensor

This paper reports on the design, processing, and characterization of a miniaturized three-dimensional force/torque (3D-FT) sensor with a load range of 10 N and 50 Nmm. The sensor consists of a CMOS sensor chip with a firmly attached, patterned Pyrex cap and a total size of only 4 × 3 × 1.5 mm³. The device is available in two designs with either one or four symmetrically placed posts. The cap is attached either by anodic bonding at the wafer level or by adhesive bonding using Cytop for single-chip processing. It concentrates the mechanical stress in the surface of the CMOS chip around the Pyrex posts. Locations of the stress sensors for maximum sensitivity and selectivity with respect to all six possible loads were determined by 3D finite-element (FE) simulations. The successful measurement of arbitrary 3D force and torque combinations is demonstrated.