Prosthetic finger phalanges with lifelike skin compliance for low-force social touching interactions

TL;DR

This study investigates synthetic finger phalanges with lifelike skin compliance for prosthetic hands, aiming to improve their physical interaction capabilities during social touching by comparing different designs and materials.

Contribution

It introduces new configurations of synthetic finger phalanges with enhanced skin-like compliance, validated through experiments and finite element simulations.

Findings

Synthetic phalanges can mimic human skin compliance more closely.

Material and internal structure variations significantly affect compliance.

Prosthetic fingers can be optimized for social interaction scenarios.

Abstract

Prosthetic arms and hands that can be controlled by the user's electromyography (EMG) signals are emerging. Eventually, these advanced prosthetic devices will be expected to touch and be touched by other people. As realistic as they may look, the currently available prosthetic hands have physical properties that are still far from the characteristics of human skins because they are much stiffer. In this paper, different configurations of synthetic finger phalanges have been investigated for their skin compliance behaviour and have been compared with the phalanges of the human fingers and a phalanx from a commercially available prosthetic hand. Handshake tests were performed to identify which areas on the human hand experience high contact forces. After these areas were determined, experiments were done on selected areas using an indenting probe to obtain the force-displacement curves. Finite element simulations were used to compare the force-displacement results of the synthetic finger phalanx designs with that of the experimental results from the human and prosthetic finger phalanges. The simulation models were used to investigate the effects of (i) varying the internal topology of the finger phalanx and (ii) varying different materials for the internal and external layers.