Upper limb prosthetic control using toe gesture sensors

A novel scheme to control upper-limb prosthesis with toe gesture sensing system is presented in this paper. In the proposed system, copper/polymer stack capacitive touch sensors fabricated on a flexible substrate, interfaced with electronics and wireless transmitters forms a smart sensing insole. The scheme takes advantage of the user making various gestures with their left and right hallux digits in the form of a Morse code. The touch results in change in capacitance of the sensors from 56 ±2 pF to 75±3 pF, which is readout by an interface circuitry. This is transmitted wirelessly to a computing system attached to the prosthetic hand, which controls it resulting in various upper-limb prosthetic gestures or grasp patterns depending on the corresponding mapped Morse code. The differential current at the output of the capacitor is converted into voltage through an integrator based capacitance-voltage converter(CVC), fabricated with 0.18μm CMOS technology. The CVC is interfaced with off-the-shelf components. Details of the sensor, sensor interface and system's design, fabrication, validation, and overall functional assessment are presented in this work to show the potential of using toe gestures for upper-limb prosthetic control.