Design and preparation of exo-glove with tactile sensing

Abstract

Doing simple daily tasks gets difficult for people with hand impairments, and to solve this, many assistive devices have been developed. However, they are too expensive, heavy, complex, and difficult to integrate with reliable tactile sensing. Thus, to address these problems, this project develops a finger flexion and extension assistive exo-glove with integrated tactile sensors based on Triboelectric Nanogenerator (TENG) technology. The glove itself is simple to wear and is 3D-printed from SIL-30 silicone, which has strong mechanical properties, including high elongation and good flexibility during bending. For mechanical assistance, a compact tendon-driven screw-guided mechanism that converts motor rotation into linear displacement of the tendon guide for controlled flexion and extension was developed. In the case of tactile feedback, at the fingertips, a TENG sensor was incorporated, which was fabricated with conductive silver ink electrodes between two layers of silicone. The performance of the sensor was experimented with both manual and machine-controlled loading conditions. Voltage outputs during hand tapping were observed to rise and fall above 20 V and this represented a high response to natural touch interactions. The electrical output was both reliable in tracking applied force and contact frequency under conditions of 1-3 N static forces and during cyclic tests with a frequency of 1-3 Hz. Also, in real-time experiments with the built-in exo-glove system, it was observed that the processed signal of tactile sensation was steady in the no-contact condition and revealed a definite change towards higher values during finger-object contact. The signal consistently exceeded a predefined threshold, enabling reliable detection of grasp events and successful triggering of the motor stopping mechanism. In order to determine the mechanical properties of the silicone material 5 ASTM D12 Standard specimens were tested in a Universal Tensile Machine. The findings were an average of 2.08 MPa tensile strength at maximum and an average of 885% elongation at break meaning that the material is very elastic and flexible. In general, the findings indicate that a soft robotic glove can be effectively used to integrate assistive movement with TENG tactile sensing. The actuation system functioned properly, enabling finger flexion and extension. The glove was fully assembled, and both the glove design and the tactile sensor were found to be functional. These results highlight the potential of the exo-glove for practical and affordable use in the future.