Nathan Roger
Senior Lecturer 
Ben Gurion University of the Negev

Biomedical engineering; design, mechanism design. Biomechanics of musculo-skeletal system. Electrical stimulation of neuromuscular tract. Design of rehabilitation systems for the disabled. Research projects: Design of neuromuscular stimulation systems for restoration of upper limb function in the paralyzed. Design of manual wheelchair propulsion system for the weak/crippled upper limb. Development of a semi-automatic surgical suturing system, Impact forces in the human body during landing from a vertical jump. In-vivo measurements on synovial joint friction coefficient.

A non-invasive hybrid system based on neuromuscular stimulation has been developed for restoration of arm function in C4 quadriplegia: A 24-channel stimulator is computer controlled and operated by voice commands from the patient. Bipolar surface electrodes on the hand, forearm, and upper arm deliver square-wave compensated double pulse constant current stimulation to the arm. Stimulation parameters are controlled from the computer software. Insufficiency in stimulation-generated muscle response is augmented by mechanical splinting and suspension systems. Residual voluntary shoulder girdle movements are utilized to transmit hand motion in the horizontal plane. Vertical motion is difficult to obtain due to peripheral denevation of the band of muscles controlling the elbow and glenohumeral joints. Custom-designed utensils compensate for this deficiency by amplifying the stimulation-generated wrist flexion. Writing function has been enhanced by the introduction of an instrumented pen with closed-loop control. Gripping force and pen/ paper pressure are the two parameters controlled simultaneously, using a mixture of control regimes: deadband control, PID with artificial intelligence algorithms, and an adaptive capability. Fast automatic techniques have been developed to en- able donning of the system in approximately 15 minutes by a non-expert. A miniaturized battery-powered domestic system is now being developed based on this design. Eating, drinking, personal grooming, drawing and writing activities have been among the activities restored to quadriplegic patients.