Mixed Dimensional ZnO/WSe Piezo-gated Transistor with Active Millinewton Force Sensing.

This work demonstrates a mixed-dimensional piezoelectric-gated transistor in the microscale that could be used as a millinewton force sensor. The force-sensing transistor consists of 1D piezoelectric zinc oxide (ZnO) nanorods (NRs) as the gate control and multilayer tungsten diselenide (WSe) as the transistor channel. The applied mechanical force on piezoelectric NRs can induce a drain-source current change (Δ) on the WSe channel. The different doping types of the WSe channel have been found to lead to different directions of Δ. The pressure from the calibration weight of 5 g has been observed to result in an ∼30% change for ZnO NRs on the p-type doped WSe device and an ∼-10% change for the device with an n-type doped WSe. The outcome of this work would be useful for applications in future human-machine interfaces and smart biomedical tools.