Flexible UV sensor based on nanostructured ZnO thin film SAW device

Flexible ultraviolet (UV) light sensor was developed using ZnO thin film based surface acoustic wave (SAW) deposited onto low cost, commercial and thin aluminum foil (50 um thickness). ZnO nanorods were further grown on the surface of the device by a simplified hydrothermal process for enhancing the sensitivity. The zero order antisymmetric (A0) and symmetric (S0) lamb wave modes were identified at 13 MHz and 30 MHz respectively. These modes were used to obtain their frequency responses at various UV light intensities. UV sensing performance was investigated at different flexible/bending positions. The results showed good sensitivity in various flexible positions, moreover, the nanorods improved the sensitivity of the sensor by 59% and 44% for A0 and S0 modes, respectively. In addition, they possessed very good repeatability and stability, hence they have great potential for flexible and wearable UV light sensing applications.