An Ultra-Flexible Tactile Sensor Using Silk Piezoelectric Thin Film

Tactile sensors are pressure/strain sensors that facilitate the measurement of mechanical stimuli arising from living and nonliving objects to fetch information about their physical state. These systems are of utmost importance in applications such as artificial intelligence, robotic-based prosthetics, and healthcare. To mimic the human nature of touch perception, the flexibility of active sensing material is a critical requirement in the construction of a tactile sensor. Finding a biocompatible, flexible material with moderately high sensitivity is the major hurdle in the development of prosthetic wearable and implantable devices. In this article, we report, for the first time, a silk-based ultra-flexible tactile sensor that draws on the piezoelectric property of silk thin film. The fabrication of the tactile sensor involves only one lithography step and one spin coating step, which makes it easy to be realized in resource-constrained laboratory settings. A systematic analysis is carried out to correlate the performance of the sensor with the properties of silk thin films prepared under different conditions. To assess the potential of the silk-based tactile sensor's utility in practical applications, the linearity, repeatability, and stability of the fabricated devices are also analyzed. Apart from that, the tactile sensor is attached to different body parts to detect and distinguish various body movements. It is observed that the silk-based tactile sensor could detect different body movements distinctly, stably, and accurately.