Improved Six-Degree-of-freedom Single-Chip Force/Moment Transducer for Instrumented Teeth

This paper presents the latest achievements in the area of instrumented teeth. It reports a six-degree-of-freedom force/moment transducer (FMT) based on a redesigned sensor chip in 350-nm CMOS technology equipped with 32 piezoresistive microsensors and capable of measuring three force and three moment components. The system was optimized by defining new positions of the stress sensing elements on the chip which maximize the smallest singular value of the sensitivity matrix of the FMT. Thereby its performance with respect to the applied load states is effectively improved. The transducer is calibrated in the clinically relevant ranges of ±3 N and ±3 N mm. Its resolutions of the three force components f
_x
, f
_y
, and f
_z
are 16 mN, 6 mN, 54 mN, respectively, while for the three moment components ms, my, and mz they are 0.069 Nmm, 0.060 Nmm, and 0.040 N mm. In comparison with the previous state of the art, this represents an improvement by a factor of up to 5. Especially the distinction between f
_z
and m
_y
improved significantly.