Hand Restoration System using Surface Electrode Array Stimulation

Abstract

Stroke is one of the leading causes of serious, long-term disabilities. Each year over 15 million people worldwide suffer from a stroke and 5 million are left permanently disabled. Loss of hand function is one of the most frequently persisting consequences of stroke and is often characterized by an inability to open the hand, due to finger extension deficit and, over time, increasing stiffness due to spasticity and muscle contractures.

There is a deficiency of effective stroke rehabilitation systems for restoration of hand function, with most existing rehabilitation methods concentrating on regaining reaching function in the arm. Consequently, the recovery of the wrist and fingers movement has a delayed progression compared with the rest of the upper-limb.

The Hand Restoration System (HaReS) has been designed for functional and motor rehabilitation of fingers and wrist in the early stages of recovery. System consists of ergonomic wearable sensors (5DT gloves and goniometers) and dedicated rehabilitation software with motivating game-based training environment that provides feedback to the patient. HaReS has been designed for a wide group of stroke patients to increase the motivation and support them in precisely performing repetitive movements. The key element of the system is novel electrical stimulation based control of the hand that uses an analogue multiplexer in conjunction with a 5x8 element electrode array and multi-channel stimulation hardware.

Surface electrode array stimulation is novel non-invasive method of muscle activation applied via adhesive electrode arrays placed on the surface of the patient skin above the location of the desired muscles. Surface electrode array stimulation is able to induce movements in paralysed or weak limb, by delivering a series of electrical pulses to associated skeletal muscles through activation of chosen elements of electrode array. Surface electrode array stimulation can be an effective technique for stroke rehabilitation of the wrist and fingers, due to its increased muscle selectivity, which is made possible by enabling an individual or selected group of array elements to be made active. However, the effectiveness of the method is strongly related to the precision and accuracy of the stimulation. Locating the optimal stimulation sites is critical to the effective application of this rehabilitation approach. An electrical stimulation technique has been developed which features a novel auto-configuration method of finding the most effective stimulation sites. The method utilises the concept of “Virtual Elements” with a constrained optimisation approach, to enable the participant to precisely perform predefined hand gestures.

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Identifiers

ORCID for Christopher Freeman: orcid.org/0000-0003-0305-9246

ORCID for Eric Rogers: orcid.org/0000-0003-0179-9398

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