A Highly Sensitive Force Sensor with Fast Response Based on Interlocked Arrays of Indium Tin Oxide Nanosprings toward Human Tactile Perception

Development of a sensor for recognizing tactile feeling is essential for realizing artificial systems that can perform human tactile functions for various applications. For achieving the capability of human tactile sensation, highly sensitive responses are required not only to static pressures but also to dynamic high-frequency vibrations. Here, a highly sensitive force sensor based on interlocked arrays of vertically aligned indium tin oxide (ITO) nanospring structures fabricated on a flexible polyethylene naphthalate substrate is presented. The combination of rigid ITO on the flexible substrate, its unique nanoscale spring-like geometry, and the interlocking configuration results in sensitive responses to both static and dynamic pressures with a sub-millisecond response time over wide pressure and frequency ranges appropriate for human tactile perception. Consequently, the sensor is capable of classifying eight fabrics possessing complex patterns with 99.8% accuracy. In addition, a flexible 14 x 14 force sensor matrix array is demonstrated, thus demonstrating the integration capability.