title: Wireless distributed functional electrical stimulation system.
abstract: BACKGROUND
  The control of movement in humans is hierarchical and distributed and uses feedback. An assistive system could be best integrated into the therapy of a human with a central nervous system lesion if the system is controlled in a similar manner. Here, we present a novel wireless architecture and routing protocol for a distributed functional electrical stimulation system that enables control of movement.
  
  
  METHODS
  The new system comprises a set of miniature battery-powered devices with stimulating and sensing functionality mounted on the body of the subject. The devices communicate wirelessly with one coordinator device, which is connected to a host computer. The control algorithm runs on the computer in open- or closed-loop form. A prototype of the system was designed using commercial, off-the-shelf components. The propagation characteristics of electromagnetic waves and the distributed nature of the system were considered during the development of a two-hop routing protocol, which was implemented in the prototype's software.
  
  
  RESULTS
  The outcomes of this research include a novel system architecture and routing protocol and a functional prototype based on commercial, off-the-shelf components. A proof-of-concept study was performed on a hemiplegic subject with paresis of the right arm. The subject was tasked with generating a fully functional palmar grasp (closing of the fingers). One node was used to provide this movement, while a second node controlled the activation of extensor muscles to eliminate undesired wrist flexion. The system was tested with the open- and closed-loop control algorithms.
  
  
  CONCLUSIONS
  The system fulfilled technical and application requirements. The novel communication protocol enabled reliable real-time use of the system in both closed- and open-loop forms. The testing on a patient showed that the multi-node system could operate effectively to generate functional movement.
authors.affiliation: School of Electrical Engineering, University of Belgrade, Belgrade, Serbia. nenad@etf.rs
authors.forename: Nenad S
authors.initials: NS
authors.lastname: Jovičić
authors.forename: Lazar V
authors.initials: LV
authors.lastname: Saranovac
authors.forename: Dejan B
authors.initials: DB
authors.lastname: Popović
mesh_terms: D000465:Algorithms; D000669:Amplifiers, Electronic; D001132:Arm / Q000502:physiology; D001676:Biofeedback, Psychology; D003199:Computer Systems; D003201:Computers; D004558:Electric Stimulation; D004599:Electric Stimulation Therapy / Q000295:instrumentation*; D004581:Electronics; D004867:Equipment Design; D018737:Hand Strength / Q000502:physiology; D006429:Hemiplegia / Q000534:rehabilitation; D006801:Humans; D018482:Muscle, Skeletal / Q000502:physiology; D012815:Signal Processing, Computer-Assisted; D012984:Software; D059015:Wireless Technology