An electrical prehension orthosis operated through activity of mastication muscle

An electrical prehension orthosis is under development to support daily activity of cervical spinal cord injury patients. The prehension orthosis has an electric motor to open/close user´s fingers, the second and the third fingers, toward a thumb fixed at opposite position. The prehension orthosis also has a unique interface for controlling it. The interface is a sensor to detect deformation (swelling) of human body surface. In this study this sensor is used to detect activity of mastication muscle. The activity of mastication muscle can be obtained by using this sensor because the mastication muscle always swells as it acts. The sensor is fixed at the user´s head by using a belt and detects user´s efforts for chewing. User can operate the electrical prehansion orthosis through gentle chewing even at the bimanual-handling tasks. Excellent operability of fingers has been demonstrated by a target user. The details of the system and results of evaluation tests are reported in this paper.