A wrist-worn computer interface including a sensor for measuring wrist tendon forces corresponding to specific finger motions including a linear array of cantilevered piezoelectric sensors configured to emit electric currents upon pressure from the wrist tendons on the tip of the piezoelectric sensors, a processing module configured for converting the electric currents generated upon pressure from wrist tendons into signals and for processing the signals to identify one or more specific finger motions, and a flexible PCB connecting the piezoelectric sensors to the processing module. A controller module is configured to cause one or more computing devices to automatically execute one or more specific commands corresponding to one or more of the specific finger motions.