PVDF-Muscovite Bimorph System as Flexible Transparent Thermal Sensor

With the rise of wearable devices, research on flexible materials has become more crucial. However, moderating the connection of multiple functions and the interaction between humans and devices is essential. Thus, the actuators and sensors become significant components in this field. This study focuses on improving the sensitivity of flexible thermal sensors to follow up on the human body’s condition. We propose a thermally sensitive system based on polyvinylidene difluoride (PVDF) and muscovite. Muscovite offers a platform for better thin film growth and stable mechanical flexibility in this system. The disparity in the coefficient of thermal expansion between muscovite and PVDF is enormous, leading to a considerable strain under a low-temperature variation. Further, PVDF is a piezoelectric material that exhibits electric polarization variations due to the internal generation of mechanical stress, producing an electric field. With a thickness of 20μm, this system can generate an output voltage of up to 2.21V at a 100^OC temperature variation. On the other hand, the transparency of PVDF /muscovite shows excellent potential for more applications, such as all-transparent wearable devices. In conclusion, considerable sensitivity can be achieved in the designed system. The subtle fluctuations of temperature can be detected daily and generate a considerable electric signal compared with a pyroelectric system. The measurement shows an effective pyroelectric coefficient of about 119.4 (10^-4C．m^-2．K^-1). Therefore, this research gives us an excellent option for integration into wearable devices.