Prototype electrically driven prosthetic hand model with experimental muscle‐rise sensor designed for use in student instruction

Abstract

Development of the Finch as an electrically driven hand prosthesis and investigation of its clinical application in recent years have led the authors to consider the possibility of its use by non‐disabled individuals at educational sites. Consequently, the authors sought to construct a modified model with electrically driven opposing fingers and investigate its potential for educational use. of this prototypical electrically driven hand prosthesis are its splint‐form forearm support body including the wrist joint immobilization orthosis for smooth opening and closing of the opposing fingers and its finger and muscle‐rise sensors. Particularly innovative aspects are its inclusion of the muscle‐rise sensor serving as a switch in the wrist immobilization orthosis and mounting of the muscle‐rise sensor on the extensor carpi radialis muscle. The wrist immobilization orthosis is an attached aluminum plate (hereinafter “metal plate") extending from the back of the hand along the postcubital major axis. When the test subject dorsiflexes their wrist the back of their hand pushes up the metal plate with the opisthenar.Thus, in the forearm postcubital region, the metal plate pushes down the muscle‐rise sensor with the wrist joint as the fulcrum, facilitating operation of the switch. The test results show that the test subject can readily open and close the finger devices unaccompanied by any need for unnatural body movement, and that use in combination with the wrist joint immobilization orthosis is effective even in those with insufficient muscle rise. Although further improvement may be necessary regarding the structure and weight, the study indicates that the electrically driven prosthetic hand model can clearly present the differences in perception and effects from those of a body‐driven prosthetic hand and that educational use will be possible. The purpose of this paper is to report the structure and function of the prototype electrically driven prosthetic hand model for educational use, present the results of utilization tests, and identify aspects that will require further development.