Environment-Resilient Graphene Vibrotactile Sensitive Sensors for Machine Intelligence

Skin-like sensors that transduce tactile pressures and vibrations with minimal environment variation on performance are crucial in robotic sensing and prosthetic skins. However, sensor performance variations under varying environmental conditions, such as temperature and humidity, are common in piezoresistive sensors because of their intrinsic materials properties. Moreover, the viscoelasticity of soft elastomers causes strain response in a time-dependent fashion, which poses sensor limitations in high-frequency tactile tasks, such as texture recognition. In this work, we demonstrate a new environment-robust tactile sensor via an interfacial engineering process for uniform graphene coating on microstructured elastomers. The sensor enables reliable pressure response over a range of temperature (25-60 degrees C) and humidity (30-90% relative humidity) conditions, with resistance variations less than 5% and 3%, respectively. It is also able to detect vibrations with frequency up to 1500 Hz. Moreover, our sensor shows ultra-high durability, with high sensitivity and low hysteresis preserved after 1 million cycles. We demonstrate applications with the sensor in epidermal signal monitoring at different arteries, as well as accurate (>95%) surface texture recognition in combination with machine learning.