title: Electrical Characterization of 3D Au Microelectrodes for Use in Retinal Prostheses.
abstract: In order to provide high-quality visual information to patients who have implanted retinal prosthetic devices, the number of microelectrodes should be large. As the number of microelectrodes is increased, the dimensions of each microelectrode must be decreased, which in turn results in an increased microelectrode interface impedance and decreased injection current dynamic range. In order to improve the trade-off envelope between the number of microelectrodes and the current injection characteristics, a 3D microelectrode structure can be used as an alternative. In this paper, the electrical characteristics of 2D and 3D Au microelectrodes were investigated. In order to examine the effects of the structural difference, 2D and 3D Au microelectrodes with different base areas but similar effective surface areas were fabricated and evaluated. Interface impedances were measured and similar dynamic ranges were obtained for both 2D and 3D Au microelectrodes. These results indicate that more electrodes can be implemented in the same area if 3D designs are used. Furthermore, the 3D Au microelectrodes showed substantially enhanced electrical durability characteristics against over-injected stimulation currents, withstanding electrical currents that are much larger than the limit measured for 2D microelectrodes of similar area. This enhanced electrical durability property of 3D Au microelectrodes is a new finding in microelectrode research, and makes 3D microelectrodes very desirable devices.
authors.affiliation: Department of Electrical and Computer Engineering, ISRC/ASRI, Seoul National University, Seoul 151-742, Korea. sangmlee@snu.ac.kr.
authors.forename: Sangmin
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Electrical and Computer Engineering, ISRC/ASRI, Seoul National University, Seoul 151-742, Korea. brise98@snu.ac.kr.
authors.forename: Jae Hyun
authors.initials: JH
authors.lastname: Ahn
authors.affiliation: Department of Electrical and Computer Engineering, ISRC/ASRI, Seoul National University, Seoul 151-742, Korea. chungh@snu.ac.kr.|Department of Ophthalmology, College of Medicine, Seoul National University, Seoul 110-744, Korea. chungh@snu.ac.kr.
authors.forename: Jong-Mo
authors.initials: JM
authors.lastname: Seo
authors.affiliation: Department of Ophthalmology, College of Medicine, Seoul National University, Seoul 110-744, Korea. chungh@snu.ac.kr.
authors.forename: Hum
authors.initials: H
authors.lastname: Chung
authors.affiliation: Department of Electrical and Computer Engineering, ISRC/ASRI, Seoul National University, Seoul 151-742, Korea. dicho@snu.ac.kr.
authors.forename: Dong-Il Dan
authors.initials: DI
authors.lastname: Cho
mesh_terms: D017097:Electric Impedance; D006046:Gold / Q000737:chemistry*; D008839:Microelectrodes; D055616:Microtechnology / Q000295:instrumentation*; D011474:Prosthesis Design; D057488:Visual Prosthesis
chemical_list: D006046:Gold
keywords: 3D microelectrode; current stimulation; electrical durability; interface impedance; retinal prosthesis