title: An optically powered single-channel stimulation implant as test system for chronic biocompatibility and biostability of miniaturized retinal vision prostheses.
abstract: A microsystem based microimplant with an optically powered single-channel stimulator was designed and developed as test system for an epi-retinal vision implant. Biostability of the hybrid assembly and the encapsulation materials were evaluated in pilot experiments in chronic implantations in a cat animal model. The implant was fabricated on a flexible polyimide substrate with integrated platinum electrode, interconnection lines, and contact pads for hybrid integration of electronic components. The receiver part was realized with four photodiodes connected in series. A parylene C coating was deposited on the electronic components as insulation layer. Silicone rubber was used to encapsulate the electronics in the shape of an artificial intraocular lens to allow proper implantation in the eye. Pilot experiments showed the biostability of the encapsulation approach and full electric functionality of the microimplant to generate stimulation currents over the implantation period of three months in two cats. In one cat, electrical stimulation of the retina evoked neuronal responses in the visual cortex and indicated the feasibility of the system approach for chronic use.
authors.affiliation: Department of Physics, Philipps University Marburg, Renthof 7, 35037 Marburg, Germany. th.schanze@web.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Schanze
authors.forename: Lutz
authors.initials: L
authors.lastname: Hesse
authors.forename: Carsten
authors.initials: C
authors.lastname: Lau
authors.forename: Nina
authors.initials: N
authors.lastname: Greve
authors.forename: Werner
authors.initials: W
authors.lastname: Haberer
authors.forename: Sascha
authors.initials: S
authors.lastname: Kammer
authors.forename: Thomas
authors.initials: T
authors.lastname: Doerge
authors.forename: Andreas
authors.initials: A
authors.lastname: Rentzos
authors.forename: Thomas
authors.initials: T
authors.lastname: Stieglitz
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000009:adverse effects / Q000737:chemistry; D002415:Cats; D004558:Electric Stimulation / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods; D004599:Electric Stimulation Therapy / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods; D004567:Electrodes, Implanted; D019544:Equipment Failure Analysis; D005240:Feasibility Studies; D005549:Foreign-Body Reaction / Q000175:diagnosis* / Q000209:etiology; D007910:Lenses, Intraocular; D008839:Microelectrodes; D055095:Optics and Photonics / Q000295:instrumentation*; D019736:Prostheses and Implants; D011474:Prosthesis Design; D012160:Retina; D014786:Vision Disorders / Q000534:rehabilitation*
chemical_list: D001672:Biocompatible Materials