Size effect in a cantilevered ZnO micro/nanowire and its potential as a performance tunable force sensor
Multi-axis force sensing in the nanonewton range is essential in M/NEMS, intelligent electron devices, and structure monitoring areas. Here a nanonewton force sensor with tunable performances based on a cantilevered ZnO micro/nanowire has been fabricated. Owing to the modification effect of the strain induced piezopotential on the carrier transport at the M/S interface, the force can be linearly related to the natural logarithm of the current. More importantly, through changing the position of the applied force along the c-axis direction of the ZnO wire, which can also be regarded as the size effect of the wire, not only do the detection limit and the sensitivity change, but also the resolution of the sensor can be effectively modulated. A mechanical model is proposed to explain the observed phenomenon. This prototype device guides the design of spatial force sensors with tunable performances, which may have great applications in smart M/NEMS, nanorobotics, high resolution touchscreens and even personal electronics.