Force-pad made from contact-electrification poly(ethylene oxide)/InSb field-effect transistor

A contact electrification field-effect transistor (CE-FET) is first made from poly(ethylene oxide)/InSb/PET(polyethylene terephthalate) on the flexible force-pad application. The CE-FET operates on a unique principle that relies on the triboelectric potential difference that is established between the two tribo-surfaces, to induce an inner electrical signal by utilizing the external frictional force. Such a signal is able to modulate the carrier transport characteristics in the FET and is self-generated to have the same effect as applying a gate signal. The traditional gate electrode in the FET is replaced by an individually mobile aluminum and a polytetrafluoroethene (PTFE) electrode to serve as a positive and negative gate voltage, respectively. The n-type rich indium (In) InSb thin film is then used as a conduction channel in the CE-FET. When the PTFE film acted as a mobile gate electrode to progressively contact the PEO surface, the drain current was increased from 6 to 12 μA by increasing the distance (d) between the PEO and the PTFE surfaces in the range from 0 to 80 μm. In contrast, when the Al film was used as a mobile electrode to gradually contact the PEO surface, the corresponding drain current decreases from 7 μA to 1.5 μA, while increasing the corresponding distance from 0 to 80 μm, respectively. Thus, the characteristic of the CE-FET has established an enhancement and depletion mode in the InSb conduction channel when the mobile electrodes of the PTFE and aluminum films were mechanically attached to the PEO surface, respectively. The CE-FET InSb is highly reliable and sensitive, which thereby opens up a new research field on the applications of the force pads.