title: Evaluation of a MEMS-based dual metal-layer thin-film microelectrode array for suprachoroidal electrical stimulation.
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.
authors.affiliation: School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China. suihong@sjtu.edu.cn
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Sui
authors.forename: Jingjing
authors.initials: J
authors.lastname: Sun
authors.forename: Liming
authors.initials: L
authors.lastname: Li
authors.forename: Chuanqing
authors.initials: C
authors.lastname: Zhou
authors.forename: Xuejiao
authors.initials: X
authors.lastname: Luo
authors.forename: Niansheng
authors.initials: N
authors.lastname: Xia
authors.forename: Yan
authors.initials: Y
authors.lastname: Yan
authors.forename: Yao
authors.initials: Y
authors.lastname: Chen
authors.forename: Qiushi
authors.initials: Q
authors.lastname: Ren
authors.forename: Xinyu
authors.initials: X
authors.lastname: Chai
mesh_terms: D000818:Animals; D002829:Choroid / Q000502:physiology*; D017097:Electric Impedance; D004558:Electric Stimulation / Q000295:instrumentation / Q000379:methods; D004567:Electrodes, Implanted; D055724:Electrophysiological Phenomena; D005071:Evoked Potentials / Q000502:physiology; D008670:Metals; D055617:Micro-Electrical-Mechanical Systems; D011474:Prosthesis Design; D011817:Rabbits; D012160:Retina / Q000502:physiology; D014793:Visual Cortex / Q000502:physiology; D057488:Visual Prosthesis
chemical_list: D008670:Metals