Piezoresistive/Piezoelectric Pressure Sensor Based on CVD-Grown ZnO Nanowires on Polyethylene Terephthalate Substrate

Recent developments in the domain of electronic materials and devices have attracted the interest of researchers toward flexible and printable electronic components like organic transistors, printable electrodes, and sensors. Zinc oxide (ZnO) nanowires (NWs) possess several excellent properties like high mobility, large exciton binding energy, and direct-band gap in addition to large piezoelectric coefficients. Here, we report a flexible piezo-resistive/piezoelectric sensor based on ZnO NWs on an indium tin oxide (ITO)-coated polyethylene terephthalate (PET) substrate. The device exhibits variation in resistance from 100 to 2400 Ω during relaxation and bending conditions, respectively. The I–V curves of the ZnO NW-based flexible pressure sensor show a transition in current conduction from 24.40 mA to 0.30 μA upon bending (to 95.5°) from flat at +5 V. We observed 10-fold enhanced variation as compared to previous reports. Improved sensitivity has been observed in our experiments due to fewer defects in CVD-grown NWs as compared with others where hydrothermally grown nanowires were used. The device fabrication methodology reported in this article requires less time and enables efficient devices to realize flexible and wearable technology.