A Reliable Strain Sensor Based on Bridging GaN Nanowires

A reliable piezoresistive strain sensor (PSS) was fabricated by using the directly bridging GaN nanowires (NWs). The bridging NWs were epitaxially grown over a deep trench on GaN-coated sapphire substrate, so homogeneous, solid, and robust connections between the electrode (GaN coating layer) and NWs can be realized without electrical contact barrier. The sensing properties of the GaN-NW PSS were investigated by measuring the deflection-induced resistance variation of NWs. The GaN-NW PSS demonstrates good repeatability, fast response speed, and a relatively high gauge factor (GF) of ~59. To our knowledge, it is the first time that the piezoresistive effect of GaN NW was investigated.