An affordable transradial prosthesis based on force myography sensor

Abstract

Forearm amputation abruptly affects the patient’s life by limiting their body functionality. Available myoelectric prosthesis somewhat can regain the lost capability of amputees. Nevertheless, there are some limitations associated with these prosthetic devices: (1) their price is excessive (2) their function mainly depends on electromyography (EMG) signals, which are quite susceptible to sweat, motion artifact, electrode shift, and other electrical interference (3) these have sophisticated hardware as well as the control system. This paper introduces an affordable transradial prosthesis controlled by the force myography (FMG) signal. In this work, a unique FMG sensor was designed for the reliable detection of muscular contractions from the remaining forearm of amputees. The sensor was fabricated using a unique mechanical assembly and specific signal conditioning circuitry. A 3D printed prosthetic hand was prepared with an individual position control strategy that receives input from the designed sensor. The designed sensor was validated by determining characteristics such as sensitivity, repeatability, hysteresis, and frequency response. Moreover, its ability to detect muscular contractions was compared with that of an EMG sensor. The designed sensor showed a good correlation (r>0.88) and higher SNR values (>42 dB) as compared to the EMG sensor. Furthermore, the developed hand prototype with the implemented control scheme was successfully verified on five amputees for performing various grasping activities. The amputees were able to control the grasping force of hand fingers with the intent of muscle contraction. The hand offered fast and intuitive operation with input from the FMG sensor.