Evaluation of a MEMS-based dual metal-layer thin-film microelectrode array for suprachoroidal electrical stimulation

IEEE Trans Neural Syst Rehabil Eng. 2013 Jul;21(4):524-31. doi: 10.1109/TNSRE.2012.2188042. Epub 2012 Apr 9.

Abstract

A double metal-layer thin-film platinum microelectrode array was fabricated for implantation between sclera and choroid based on MEMS processing techniques and photosensitive polyimide material. The array was composed of 60 stimulating sites (6 × 10) and four selectable returning electrodes. The diameter of each stimulating electrode was 350 μ m with a center-to-center spacing of 750 μm. The transient voltage responses of the electrode to current pulse stimulation indicated a charge-injection capacity greater than 52.1 μ C/cm (2) . Acute in vivo animal experiments showed that the implicit time of electrically evoked potentials (EEPs) was 17.09±1.45 ms at a threshold current of 25.55 ±5.43 μA for a full-row of simultaneously stimulated electrodes (i.e., current applied simultaneously to each of the 10 electrodes). Individual electrode stimulation threshold was 48.57 ±6.90 μA. The corresponding threshold charge densities were 13.28 ±2.82 μC/cm (2) and 25.24 ±3.59 μC/cm (2) , respectively. The spatial spread of the maximally recorded P1 response in the EEPs indicated a correspondence between the retinal stimulation site and the focal response location in the cortex. This method of array fabrication is suitable for acute suprachoroidal stimulation, and has a potential use for the fabrication of a visual prosthesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Choroid / physiology*
  • Electric Impedance
  • Electric Stimulation / instrumentation
  • Electric Stimulation / methods
  • Electrodes, Implanted
  • Electrophysiological Phenomena
  • Evoked Potentials / physiology
  • Metals
  • Micro-Electrical-Mechanical Systems*
  • Prosthesis Design*
  • Rabbits
  • Retina / physiology
  • Visual Cortex / physiology
  • Visual Prosthesis*

Substances

  • Metals