A figure gesture sensing device includes a ring-shaped housing, a transmitter, a receiver, and a computer processor. The housing is configured to be worn on a finger of a user. The transmitter is disposed in the housing and configured to emit a first signal into the finger of the user. The receiver is disposed in the housing and configured to detect a second signal. The second signal represents a resonance of the first signal emitted by the transmitter through the finger of the user. The computer processor is operatively coupled to the receiver and is configured to detect a motion gesture of the finger wearing the finger ring with respect to another portion of the human body based on the second signal. In some cases, the transmitter is configured to emit an ultrasonic acoustic signal, a low voltage electrical signal, or a radio frequency signal.