Multifunctional sensor based on organic field-effect transistor and ferroelectric poly(vinylidene fluoride trifluoroethylene)

A multifunctional sensor that responds to all – static/quasi-static or dynamic temperature or force – is reported. The sensor is based on a ferroelectric poly(vinylidene fluoride trifluoroethylene) (P(VDF-TrFE)) capacitor connected to the gate of organic field-effect transistor (OFET). Both, the P(VDF-TrFE) capacitance and the output voltage of the P(VDF-TrFE)/OFET sensor exhibit a logarithmic response to static compressive force, leading to higher sensitivity for small forces. In addition, both the P(VDF-TrFE) capacitance and the output voltage of the P(VDF-TrFE)/OFET sensor exhibit a linear dependence on the static/constant temperature. Response to static force or temperature is observed irrespective of whether P(VDF-TrFE) is in ferroelectric or paraelectric states, confirming that piezo/pyroelectricity is not essential when monitoring static events. The piezo/pyroelectricity become activated during dynamic events (dynamic force or temperature) when the ferroelectric P(VDF-TrFE)/OFET sensor is used. The obtained results indicate different sensing mechanisms for static and dynamic stimuli. Consequently, by choosing P(VDF-TrFE) layers in ferroelectric or paraelectric states a route for differentiating between the static and dynamic stimuli may exist.