Static and dynamic response of a multiplexed-array piezoresistive contact sensor

Multiplexed piezoresistive sensor arrays hold great potential for measuring contact stress distributions for orthopedic research applications. However, their acceptance has been handicapped by output drift and the fact that their dynamic response has not been well characterized. In this report, the static and dynamic responses of one device of this class (the K-Scan piezoresistive contact stress sensor) are formally characterized using a specially made pressure vessel that provides spatially homogeneous contact stress. Drift was predominant early in static loading, reaching relative errors of approximately 30 percent over a 10-min period. During loading, first-order dynamic analysis showed that the time constant land time lag) was nearly zero and there was little attenuation of the output up to 20 Hz. A deconvolution algorithm proved capable of compensating for the great majority of static drift.