title: Braided multi-electrode probes: mechanical compliance characteristics and recordings from spinal cords.
abstract: OBJECTIVE
  To test a novel braided multi-electrode probe design with compliance exceeding that of a 50 µm microwire, thus reducing micromotion- and macromotion-induced tissue stress.
  
  
  METHODS
  We use up to 24 ultra-fine wires interwoven into a tubular braid to obtain a highly flexible multi-electrode probe. The tether-portion wires are simply non-braided extensions of the braid structure, allowing the microprobe to follow gross neural tissue movements. Mechanical calculation and direct measurements evaluated bending stiffness and axial compression forces in the probe and tether system. These were compared to 50 µm nichrome microwire standards. Recording tests were performed in decerebrate animals.
  
  
  RESULTS
  Mechanical bending tests on braids comprising 9.6 or 12.7 µm nichrome wires showed that implants (braided portions) had 4 to 21 times better mechanical compliance than a single 50 µm wire and non-braided tethers were 6 to 96 times better. Braided microprobes yielded robust neural recordings from animals' spinal cords throughout cord motions.
  
  
  CONCLUSIONS
  Microwire electrode arrays that can record and withstand tissue micro- and macromotion of spinal cord tissues are demonstrated. This technology may provide a stable chronic neural interface into spinal cords of freely moving animals, is extensible to various applications, and may reduce mechanical tissue stress.
authors.affiliation: School of Biomedical Engineering, Science and Health System, Drexel University, Philadelphia, PA, USA.
authors.forename: Taegyo
authors.initials: T
authors.lastname: Kim
authors.forename: Almut
authors.initials: A
authors.lastname: Branner
authors.forename: Tanuj
authors.initials: T
authors.lastname: Gulati
authors.forename: Simon F
authors.initials: SF
authors.lastname: Giszter
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D003943:Diagnostic Techniques, Neurological / Q000295:instrumentation*; D055119:Elastic Modulus; D004553:Electric Conductivity; D004567:Electrodes, Implanted; D004867:Equipment Design; D019544:Equipment Failure Analysis; D046228:Microarray Analysis / Q000295:instrumentation; D008839:Microelectrodes; D018670:Monitoring, Ambulatory / Q000295:instrumentation*; D009046:Motor Neurons / Q000502:physiology*; D011892:Rana catesbeiana; D013116:Spinal Cord / Q000502:physiology*; D013718:Tensile Strength