Semi-powered exoskeleton that regulates the muscular activity of jaw movement for oral functional rehabilitation/training.

The sequential oral functions of mastication and swallowing are well tuned in humans. To prevent oral hypofunction as a risk factor for systemic frailty by oral motor training, semi-powered exoskeleton was developed and evaluated its loading/assist effects by monitoring electromyography signals and saliva secretion in healthy persons. The actuator of the driving unit combined mechanical and powered mechanics and was driven alternatively by an unpowered stainless-steel spring system for jaw-opening training by loading and a powered shape-memory alloy spring system to assist jaw closing. Sequential device movement was controlled by two electronic circuits with two magnetic switching systems to match human jaw movement. This exoskeleton realized a 25% increase of jaw-opening muscular activity for training, 15% saving of jaw-closing muscular activity for assistance, and 15% enhancement of saliva secretion, which could contribute to the prevention of oral frailty by maintenance and strengthening of oral function in the upcoming super-aging society.