Abstract:
The primary function of a prosthetic device is to provide assistive support for patients with upper
or lower limb amputation. Among the upper limb amputations, most of the patients with trans-metacarpal
amputation avoids the use of prosthetics due to the high cost and complex nature of the commercially
available prosthetics. These commercially available prostheses lack certain features, like adaptive grasp
and comfort. In order to overcome these problems, 3D printing has shown a promising path in developing
quick and customizable solutions using modern technology. Despite the importance of adaptive grasp in a
prosthesis, literature shows that studies related to improving adaptive grasp seems to be limited.
The purpose of this study is to improve the adaptive grasp mechanism used in mechanical prosthesis to
effectively utilize the limited angle of the wrist to produce enough gripping force for better functionality.
The typical angle of motion of the healthy person, the limitations and complications occurring were found
and the effects of trans-metacarpal amputation to the motion of the wrist were analysed. According to the
findings the design of the prosthesis was started using Computer Aided Designing (CAD) software and
necessary improvements needed were taken into consideration during the design phase of the new
prosthesis and the mechanism. The proper material was selected to be used in the 3D printer and the
prosthesis was printed and tested for adaptive grasp and comfort. Whipple Tree mechanism was used to
improve the adaptive grasp through proper force distribution. It was found that this kind of prosthetic
hands will help the amputee to grasp complex shaped objects which cannot be grasped by commercially
available prosthetic devices. Moreover, the ‘Flexi’ material will give enough comfort to the amputee during
operation.
