Flexure Hinge Based Fully Compliant Prosthetic Finger

Abstract

A prosthetic hand is usually made by rigid body mechanism with ropes and pulleys. Such a hand is not “soft” to patients and nor to objects to be manipulated by the hand. In this paper, the concept of compliant mechanism is applied to a prosthetic hand. A fully compliant monolithic prosthetic finger was designed and constructed with the 3D printing technology. Such a finger may be called an all-in-one piece finger. The main challenge in designing and constructing such a finger lies in the design of flexure hinge. A new design process was proposed, which takes the flexure hinge in the context of the prosthesis finger as a 3D object as opposed to the literature that treats it as a 2D object. A new prosthetic finger was then constructed with the 3D printing technology. Another contribution is the proposal of a score system to give a qualitative evaluation of the shape of flexure hinge. Finally, a fully compliant finger with a monolithic structure and flexure hinge was built.