Designing a userfriendly device to restore hand function after spinal cord lesion or stroke

Background

Accidents like cervical spinal cord injury (e.g. after breaking the neck) or an ictus can lead to paralysis of the arm and hand. In many cases this paralysis is partial, such that for example some wrist movement is possible but the fingers cannot be used. The wrist movement can be measured by electrodes on the skin of the forearm as myoelectric signals (MES). Fingers can be stimulated to extension or flexion by electrical stimulation of the muscle nerves (FES), likewise via electrodes on the forearm.

It has been clinically demonstrated that MES can be used to control FES to restore handfunction using a specialized electronic device. Currently the prototypes are pocket size and battery powered. Electrodes are self adhesive pads that must be placed on the skin at certain subject dependent spots on the forearm. These are connected with the electronics using wires.

Clinical studies have shown feasibility of the system and that it can be applied by therapists and patients as is to achieve functional benefits.

However, solving some design issues will beyound doubt make the system more userfriendly and functional; thus more successful as a product.

An electrode mount for facilitating donning and doffing in autonomy

An artistic and functional design in leather and cotton has been proposed by Leonardo deCarlo in his masters thesis in Industrial Design. This splint can place the electrodes on the forearm in custumizable fashion. It uses gold plated connectors to provide contact between electrodes and electronics.
The only similar device is the former Handmaster, now H200 from Bioness.
Further development of the designs should go in the direction of minimization of visual impact and production cost.

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