A sensor, in accordance with aspects of the present technique, is provided. The sensor comprises a membrane formed of gallium nitride. The membrane is disposed on a substrate, which is wet-etched to form a closed cavity. The membrane exhibits both a capacitive response and a piezo-response to an external stimulus. The sensor further includes a circuit for measuring at least one of the capacitive response or the piezo-response. In certain aspects, the sensor may be operable to measure external stimuli, such as, pressure, force and mechanical vibration.