Fabrication of single-electrode piezoelectric motion sensor with InN nanowires

We discuss the fabrication and characterization of flexible piezoelectric motion sensors (PMSs) with single-electrode (SE) configuration. As a response medium of the devices, InN nanowires (NWs), formed on Si(111) substrates by a plasma-assisted molecular beam epitaxy, were used. For comparison, the PMSs with two electrodes (TEs) were prepared. The performances of the PMSs were analyzed depending on device parameters such as bending frequency, operation time, relative humidity, and bending cycle. For example, the output voltage of the SE-PMS with the InN NWs aligned along the bending direction was measured to be 10.65 V, which is higher than that (7.1 V) of the TE device. To evaluate the possibility for real-life applications, the flexible PMSs were attached to a human finger and their output signals were measured depending on the movement angle.