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

Abstract

A B S T R A C TA 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.

Organic Thin Film Transistors With Multi-Finger Contacts as Voltage Amplifiers

“…The data of Fig. 6 suggests that regardless of the value of R d , V ds operation point of at least −2.5 V is needed to reach the maximum voltage gain when V g oscillates around −2 V. One can also infer that the resistance between source and drain is ∼100 k , a factor of ∼10 smaller when compared to DNTT transistors with standard source/drain contacts with L = 30 µm and W = 1 mm [10]. This decrease is important for the reduction in both V dd and R d .…”

“…Being an integral part of an analog sensor, the OTFT can provide two functions. It can act as a signal transducer by converting the physical stimulus to voltage [10] and a signal amplifier. The transconductance and geometry of the transistor play an important role for the latter.…”

Flexible Multifunctional Sensors for Wearable and Robotic Applications

“…While at an early stage, multifunctional sensors based on piezoelectric OFET have been made of several subcells and each cell acts as a single mode sensor. [92] Based on this capacitance change, Hannah et al fabricated a multifunctional sensor include PVDF-TrFE capacitor combined with an OFET for static/quasi-static force or temperature; see Figure 7a. Using a sequential and area selective poling process, one composite element can be either piezoelectric and another is pyroelectric for pressure and temperature sensing, respectively.…”

“…[39,91] For instance, Graz et al [91] fabricated a flexible bifunctional sensor with two integrated sensing elements www.advmattechnol.de based on a composite foil of lead titanate (PbTiO 3 ) nanoparticles embedded in an PVDF-TrFE matrix. [92] In the above discussions, the sensors are able to detect force or temperature at one time. The capacitance of PVDF-TrFE can be changed with a "static" force or temperature, and the changes in output are not driven by the piezoelectricity or pyroelectricity of PVDF-TrFE.…”

“…A pressure sensitivity of ≈7.5 pF N −1 was obtained in the range from 0 to ≈0.5 N and temperature sensitivity of ≈7 pF per °C in the temperature range of 19-47 °C. [6] The approach greatly reduced the complexity in structural integration, eliminated, or minimized signal interferences coupled by strain, significantly reduced the power consumption, and decreased the failure rate in production due [92] Copyright 2018, Elsevier. Multimodal piezoelectric OFET sensors can provide simultaneous sensing of both temperature and pressure.…”