Inefficient Force Generation in 3-D Printed Prosthetics

Abstract

The process of 3-d printing prosthetic hands has been used to make prosthetics more widely available by lowering the cost. However, many of these devices are not mechanically tested once they are constructed and they may not achieve their intended function. This study quantifies the efficiency and magnitude of mechanically activated grip strength in a 3-d printed prosthetic hand. A rig stabilized the hand on a dynamometer at an angle such that added weight created a constant downward force and engaged the grip. We tested the hypothesis that the presence of the hand would act as a friction device and propagate less force on the dynamometer when engaged than weights alone. The results supported the hypothesis and can aid in classifying the function of the hand for certain tasks such as holding a cup. This study can inform new designs to improve the efficiency of grip strength in similar devices. Furthermore, quantitative data on the strength of the fingers can better inform how custom hand devices will be suited to specific tasks.