Fully 3D Printed Flexible, Conformal and Multi-directional Tactile Sensor with Integrated Biomimetic and Auxetic Structure

Abstract

Abstract Tactile sensors are instrumental for developing the next generation of biologically inspired robotic prostheses with tactile feedback capability. However, current sensing technology is still less than ideal either in terms of sensitivity under high pressure or compliance with uneven working surfaces. Also, the fabrication of tactile sensors often requires the use of highly sophisticated and costly manufacturing processes further limiting the widespread application of the technology. Here, we challenge the current perspective and propose the use of an in-house 3D printing system to develop a new conformal tactile sensor with enhanced sensing performance. The ability of the sensor to detect multi-directional stimuli is achieved through the integration of the auxetic structure and interlocking features. The unique design of our sensor allows for an extended sensing range (from 0.1 to 0.26 MPa) whilst providing sensitivity on both normal and shear directions at 0.63 KPa− 1 and 0.92 N− 1, respectively. This is further complemented by capacity of the sensor to detect small temperature variations between 40 and 90°C. To demonstrate the feasibility of our approach, the tactile sensor is printed in situ on the fingertip of an anthropomorphic robotic hand, the proximal femur head and lumbar vertebra. The results suggest that it is possible to gain sensorimotor control and temperature sensing ability in artificial upper limbs whilst monitoring the bone-on-bone load, thus opening the door to a new generation of tactile sensors with novel auxetic structure design and enhanced performance for application in human prosthetics.