In this paper, a highly sensitive strain sensor with vertically aligned zinc oxide (ZnO) nanowire arrays on polyethylene terephthalate (PET) film was reported. The device fabrication includes conventional photolithography, metallization, and ZnO nanowire growth through a hydrothermal method. I-V characteristics of the device were highly nonlinear due to the Schottky contact between the nanowire and the gold (Au) electrode. The conductivity of the device is significantly tuned by the change of ZnO/Au Schottky barrier that reflects the strain-induced piezoelectric potential. A gauge factor up to 1813 was obtained from this strain senor, which is higher than the previously reported device based on a lateral ZnO microwire. Theoretical analysis of the piezotronic effect shows that the working nanowire with the largest conductivity change dominates the performance of the device. The non-working nanowire has limited adverse effect on the performance, which explains the robust performance of this novel strain sensor. The stability and fast response of the sensor were also investigated. The sensitive and robust strain sensor is expected to find applications in civil, medical, and other fields.
Bibliographical noteFunding Information:
The authors are truly grateful for the financial support from the Department of Mechanical Engineering and the College of Science and Engineering of the University of Minnesota . The authors would like to thank the National Science Foundation for its financial support ( ECCS-1150147 ). Parts of this work were carried out in Characterization Facility, University of Minnesota, which receives partial support from NSF through the MRSEC program.
- Gauge factor
- Nanowire array
- Piezotronic effect
- Strain sensor