title: A low-cost multichannel wireless neural stimulation system for freely roaming animals.
abstract: OBJECTIVE
  Electrical stimulation of nerve tissue and recording of neural activity are the basis of many therapies and neural prostheses. Conventional stimulation systems have a number of practical limitations, especially in experiments involving freely roaming subjects. Our main objective was to develop a modular, versatile and inexpensive multichannel wireless system able to overcome some of these constraints.
  
  
  METHODS
  We have designed and implemented a new multichannel wireless neural stimulator based on commercial components. The system is small (2 cm × 4 cm × 0.5 cm) and light in weight (9 g) which allows it to be easily carried in a small backpack. To test and validate the performance and reliability of the whole system we conducted several bench tests and in vivo experiments.
  
  
  RESULTS
  The performance and accuracy of the stimulator were comparable to commercial threaded systems. Stimulation sequences can be constructed on-the-fly with 251 selectable current levels (from 0 to 250 µA) with 1 µA step resolution. The pulse widths and intervals can be as long as 65 ms in 2 µs time resolution. The system covers approximately 10 m of transmission range in a regular laboratory environment and 100 m in free space (line of sight). Furthermore it provides great flexibility for experiments since it allows full control of the stimulator and the stimulation parameters in real time. When there is no stimulation, the device automatically goes into low-power sleep mode to preserve battery power.
  
  
  CONCLUSIONS
  We introduce the design of a powerful multichannel wireless stimulator assembled from commercial components. Key features of the system are their reliability, robustness and small size. The system has a flexible design that can be modified straightforwardly to tailor it to any specific experimental need. Furthermore it can be effortlessly adapted for use with any kind of multielectrode arrays.
authors.affiliation: Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hung Hom, Hong Kong.
authors.forename: Monzurul
authors.initials: M
authors.lastname: Alam
authors.forename: Xi
authors.initials: X
authors.lastname: Chen
authors.forename: Eduardo
authors.initials: E
authors.lastname: Fernandez
mesh_terms: D000818:Animals; D001921:Brain / Q000166:cytology / Q000502:physiology*; D004558:Electric Stimulation / Q000379:methods; D004567:Electrodes, Implanted / Q000191:economics; D004867:Equipment Design / Q000191:economics / Q000295:instrumentation / Q000379:methods; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D013686:Telemetry / Q000191:economics / Q000295:instrumentation* / Q000379:methods; D059015:Wireless Technology / Q000191:economics / Q000295:instrumentation*