Response of P(VDF-TrFE) sensor to force and temperature

Responses of a tactile sensor to force (0 to 9 N) and temperature (15 to 47°C) are investigated. The sensor is based on ferroelectric polyvinylidene fluoride — trifluoroethylene (P(VDF-TrFE)) copolymer. The 2.5-μm-thick copolymer layer was sandwiched between aluminum and gold electrodes and the active sensing area was 25 mm². The response of the sensor was measured in a form of capacitance recorded at 2 kHz. The capacitance was measured in a steady-state condition, i.e. after the force and temperature have stabilized. We have found that the sensor´s sensitivity to temperature is comparable to that of force, and even greatly exceeds the force sensitivity when dealing with forces larger than 3 N. This is because the response of the sensor to temperature is approximately linear, while the response to the applied force is logarithmic. Consequently, at the lower end of applied forces (< 0.5 N), the sensitivity is 7.5 pF/N while the temperature sensitivity is about 7 pF/°C within the whole temperature range.