A Tactile Sensing System Based on the Triboelectric Nanogenerator for Prosthetic Application

Abstract

The distribution of interfacial stress between the amputee's residual limb and the prosthetic socket is thought to be directly related to comfort. Prosthetic sockets are custom-made and the current technology is very mature, whether, by manual molding or 3D scanning, the prosthesis can be made to fit the patient's residual limb, but when the patient actually wears the prosthesis, the wearer may still experience discomfort due to long wear time and foreign body friction. Therefore, researchers have been interested in quantifying these interfacial stresses in order to assess the extent of any potential damage to the residual limb and to reduce the cost of prosthetic fabrication by avoiding repetitive changes to the prosthesis. However, the existing pressure sensors are not only expensive but also have compatibility problems with the residual limb and are prone to instability under the influence of the external environment, which greatly affects the actual force readings in the area. Here, we developed a tactile sensor by triboelectric nanogenerator(TENG), which collects force energy by triboelectric effect, and its wide material selection, easy fabrication, and self-driving properties are receiving more and more attention. In our research, we propose to develop a multi-point array tactile sensor based on two materials: polydimethylsiloxane (PDMS) and polycaprolactone (PCL). The surface of PDMS has a droplet microstructure, and PCL is made into a nanofiber film by electrospinning to increase the specific surface area of the material in contact to improve the output characteristics of the device and achieve a larger detection range and sensitivity. In addition to the excellent durability at 10,000 cycles, the characteristics of the device also show good stability at different humidity and temperature. Finally, we integrated this multi-point array sensor with a multi-channel measurement system, attached it to the contact interface of a 3D-printed residual limb and prosthetic model, and collected real-time correspondence signals from the compressed side to demonstrate the feasibility of this application. We believe that this novel design offers a new approach to improve the comfort of prosthetic wear for amputees and has considerable potential.