Electrical characterization of 26 × 26 ground reaction sensor array interfaced with two parallel electronic detection channels

This paper presents the electrical characterization results of a 26 x 26 high-density ground reaction sensor array (HD-GRSA) interfaced with two parallel electronic detection channels. The system was developed for improving inertial measurement unit (IMU) positioning accuracy. The HD-GRSA is composed of 26 x 26 sensing nodes, which can measure dynamic ground force and shear strain associated with a ground locomotion gait. Each electronic detection channel consists of a front-end multiplexer that can sequentially connect individual sensing nodes from a 13 x 13 sub-array to a capacitance-to-voltage (C/V) converter followed by a 12-bit algorithmic ADC. The electronics were fabricated in a 0.35 μm CMOS process occupying an area of 7.7 mm2 for each channel while dissipating a DC power of 3 mW from a 3V supply. The HD-GRSA demonstrates the designed functionality achieving a gait ground velocity resolution of approximately 95 μmRMS/sec, limited by the electronic interference signals due to the long metal traces on the sensor array. Further performance improvement is expected by employing interference suppression techniques and better matching for critical wiring traces.