Hand-gesture recognition using self-powered and single-electrode motion sensors fabricated with InN nanowires.

The ability to accurately monitor human motions such as hand-gestures is essential for establishing human-machine interface (HMI) systems for application in cutting-edge technologies such as robotics, artificial intelligence, and the internet of things. In this study, we developed self-powered and single-electrode piezoelectric motion sensors (PMSs) to precisely monitor hand-gestures. The sensors are based on semiconductor InN nanowires (NWs) and graphene as the response medium and channel of carrier movement, respectively. Compared to motion sensors with a double-electrode configuration, the single-electrode device offers notable advantages, including structural simplicity, elimination of the shielding effect of the top electrode, and a reduced risk of failure resulting from short-circuiting. Systematic analysis of the self-powered PMSs by varying the degree of strain, relative humidity, number of bending cycles, and operational time (up to 30 days) indicates that the device performance is sufficient for practical application. A PMS module composed of 14 chips attached to the finger joints of a left hand was able to successfully distinguish hand-gestures corresponding to the volume of an object (softball, baseball, and golf ball). This result demonstrates that single-electrode PMSs with InN NWs could contribute to realizing sophisticated HMI technology.