title: Electrical stimulation of retinal ganglion cells with diamond and the development of an all diamond retinal prosthesis.
abstract: Electronic retinal implants for the blind are already a market reality. A world wide effort is underway to find the technology that offers the best combination of performance and safety for potential patients. Our approach is to construct an epi-retinally targeted device entirely encapsulated in diamond to maximise longevity and biocompatibility. The stimulating array of our device comprises a monolith of electrically insulating diamond with thousands of hermetic, microscale nitrogen doped ultra-nanocrystalline diamond (N-UNCD) feedthroughs. Here we seek to establish whether the conducting diamond feedthroughs of the array can be used as stimulating electrodes without further modification with a more traditional neural stimulation material. Efficacious stimulation of retinal ganglion cells was established using single N-UNCD microelectrodes in contact with perfused, explanted, rat retina. Evoked rat retinal ganglion cell action potentials were recorded by patch clamp recording from single ganglion cells, adjacent to the N-UNCD stimulating electrode. Separately, excellent electrochemical stability of N-UNCD was established by prolonged pulsing in phosphate buffered saline at increasing charge density up to the measured charge injection limit for the material.
authors.affiliation: Research School of Biology, Australian National University, Acton, ACT 0200, Australia.
authors.forename: Alex E
authors.initials: AE
authors.lastname: Hadjinicolaou
authors.forename: Ronald T
authors.initials: RT
authors.lastname: Leung
authors.forename: David J
authors.initials: DJ
authors.lastname: Garrett
authors.forename: Kumaravelu
authors.initials: K
authors.lastname: Ganesan
authors.forename: Kate
authors.initials: K
authors.lastname: Fox
authors.forename: David A X
authors.initials: DA
authors.lastname: Nayagam
authors.forename: Mohit N
authors.initials: MN
authors.lastname: Shivdasani
authors.forename: Hamish
authors.initials: H
authors.lastname: Meffin
authors.forename: Michael R
authors.initials: MR
authors.lastname: Ibbotson
authors.forename: Steven
authors.initials: S
authors.lastname: Prawer
authors.forename: Brendan J
authors.initials: BJ
authors.lastname: O'Brien
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003460:Crystallization; D018130:Diamond / Q000737:chemistry*; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D004867:Equipment Design; D005074:Evoked Potentials, Visual; D006801:Humans; D008839:Microelectrodes; D051381:Rats; D012165:Retinal Ganglion Cells / Q000502:physiology*; D057488:Visual Prosthesis
chemical_list: D018130:Diamond