Liquid Metal-Based Wearable Tactile Sensor for Both Temperature and Contact Force Sensing

Abstract

Wearable tactile sensors can be used for haptic perception and are widely utilized in soft robotics, intelligent prosthetics, and other human interfaced/interface applications. The development of tactile sensors with for multifunctional tactile sensing capacity remains a challenge. This article presents the design and fabrication of a wearable tactile sensor based on galinstan liquid metal for the simultaneous sensing of temperature and contact force independently. The decoupling of temperature and contact force sensing, which is based on the measured output voltage signals, is achieved by a designed Wheatstone bridge circuit and by the structural design of the fingerprint-patterned microfluidic channels and the top oval-shaped protrusion. Characterization tests show that the fabricated tactile sensor has a relatively high force sensing sensitivity of 0.32 N ^-1 and its temperature sensing sensitivities are 0.41% °C ^-1 at 20~50 °C and 0.21% °C ^-1 at 50~80 °C. Two wearable tactile sensors are worn on the index finger and thumb of the human hand and are used to detect temperature changes and contact forces during grasping applications. The results show that the developed liquid metal-based tactile sensor has a high flexibility and durability, and can accurately measure the contact forces and temperatures simultaneously. Thus, the developed wearable tactile sensor has great potential for robotic manipulation and healthcare condition sensing in humans.