title: A new high-density (25 electrodes/mm²) penetrating microelectrode array for recording and stimulating sub-millimeter neuroanatomical structures.
abstract: OBJECTIVE
  Among the currently available neural interface devices, there has been a need for a penetrating electrode array with a high electrode-count and high electrode-density (the number of electrodes/mm(2)) that can be used for electrophysiological studies of sub-millimeter neuroanatomical structures. We have developed such a penetrating microelectrode array with both a high electrode-density (25 electrodes/mm(2)) and high electrode-count (up to 96 electrodes) for small nervous system structures, based on the existing Utah Slanted Electrode Array (USEA). Such high electrode-density arrays are expected to provide greater access to nerve fibers than the conventionally spaced USEA especially in small diameter nerves.
  
  
  METHODS
  One concern for such high density microelectrode arrays is that they may cause a nerve crush-type injury upon implantation. We evaluated this possibility during acute (<10 h) in vivo experiments with electrode arrays implanted into small diameter peripheral nerves of anesthetized rats (sciatic nerve) and cats (pudendal nerve).
  
  
  RESULTS
  Successful intrafascicular implantation and viable nerve function was demonstrated via microstimulation, single-unit recordings and histological analysis. Measurements of the electrode impedances and quantified electrode dimensions demonstrated fabrication quality. The results of these experiments show that such high density neural interfaces can be implanted acutely into neural tissue without causing a complete nerve crush injury, while mediating intrafascicular access to fibers in small diameter peripheral nerves.
  
  
  CONCLUSIONS
  This new penetrating microelectrode array has characteristics un-matched by other neural interface devices currently available for peripheral nervous system neurophysiological research.
authors.affiliation: Department of Bioengineering, University of Utah, Salt Lake City, UT, USA.
authors.forename: H A C
authors.initials: HA
authors.lastname: Wark
authors.forename: R
authors.initials: R
authors.lastname: Sharma
authors.forename: K S
authors.initials: KS
authors.lastname: Mathews
authors.forename: E
authors.initials: E
authors.lastname: Fernandez
authors.forename: J
authors.initials: J
authors.lastname: Yoo
authors.forename: B
authors.initials: B
authors.lastname: Christensen
authors.forename: P
authors.initials: P
authors.lastname: Tresco
authors.forename: L
authors.initials: L
authors.lastname: Rieth
authors.forename: F
authors.initials: F
authors.lastname: Solzbacher
authors.forename: R A
authors.initials: RA
authors.lastname: Normann
authors.forename: P
authors.initials: P
authors.lastname: Tathireddy
mesh_terms: D000818:Animals; D002415:Cats; D003943:Diagnostic Techniques, Neurological / Q000295:instrumentation*; D017097:Electric Impedance; D004558:Electric Stimulation / Q000295:instrumentation*; D004567:Electrodes, Implanted; D004867:Equipment Design; D019544:Equipment Failure Analysis; D046228:Microarray Analysis / Q000295:instrumentation*; D008839:Microelectrodes; D036103:Nanotechnology / Q000295:instrumentation*; D010525:Peripheral Nerves / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley