Development of a wireless ditributed three channel stimulator used for automatic triggering of stimulation to enable co-ordinated task execution of stroke patients.

Abstract

Each year, hundreds of thousands of people are affected by a neurological related disease or injury causing some of them partial or complete dysfunction of one or more limbs. Functional Electrical Stimulation (FES) techniques have shown a significant improvement in mobility and function for many of these people. FES is an artificial technique of stimulating motor nerves to cause contraction of muscles. Depending on the extent of the injury and the movement disorder, multiple channels of stimulation and sensors might be necessary. However, this results in a complex multi-channel stimulator which is often rejected by the user due to the size, complexity and cosmesis. These issues can be addressed to some extent by using distributed systems that split the complex function of the multi-channel stimulator into multiple local stimulators around the body. However, using conventional techniques will result in a complex network of wires making it difficult and inconvenient for the wearer. The obvious solution is to replace wires with a wireless network where each node from the network communicates with one or multiple nodes, and is small enough to be placed where needed. Because of the safety implications of this application, any wireless network of this type must be at least as reliable as a wired system with latencies that do not weaken the performance of the system. This research involves identifying the wireless technology that can ensure reliability, short latency and low power consumption in environments where FES is used. In addition, the research investigates a control strategy for a wireless distributed FES system which consists of three-channel stimulators and four sensors. This system is designed to correct drop foot and assist reciprocal arm swing in walking mode, and enables reaching and grasping stimulation when the user is stationary. This combination of a wireless network of stimulators and sensors allows the development of a new generation of FES systems that are convenient for use and which are expandable so that new sensors or stimulators can be easily added to the network to meet the needs of each individual user. The experimental results confirmed the feasibility of a wireless network of stimulators and sensors using ZigBee, and indicated that the control strategy was successful in enabling the required stimulation channels.