Photovoltaic retinal prosthesis: implant fabrication and performance
Photovoltaic retinal prosthesis: implant fabrication and performance
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DOI：
10.1088/1741-2560/9/4/046014
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发表时间：
2012-08-01
影响因子：
4
通讯作者：
Palanker, D. V.
中科院分区：
文献类型：
--
作者：
Wang, Lele;Mathieson, K.;Palanker, D. V.
这项工作的目的是开发和测试一种光伏视网膜假体，用于恢复因退行性视网膜疾病而失明的患者的视力。采用硅集成电路/MEMS工艺制作了一种用于视网膜下刺激的硅光电二极管阵列。二维阵列中的每个像素包含三个串联的光电二极管，它们将脉冲近红外光光电转换为双相电流，以刺激附近的视网膜神经元，而无需有线电源连接。装置厚度选择为30 μ m，以吸收大部分光，同时仍然足够薄以用于视网膜下植入。有源电极和返回电极将电流限制在每个像素附近，并溅射涂有氧化铱，以提高电荷注入水平并提供稳定的神经界面。像素由5 μ m宽的沟槽隔开，以使它们电隔离，并允许营养物扩散通过器件。三种尺寸的像素（280，140和70 μ m）与80，40和20 μ m直径的有源电极制造。一个二极管、两个串联连接的二极管和三个串联连接的二极管结构的导通电压分别约为0.6、1.2和1.8 V。在880 nm波长处测得的每个二极管的光响应度类似于0.36 A W-1，在零电压偏置下，并且与暴露的硅面积成比例。对于所有三种像素尺寸，反向偏置暗电流足够低（
The objective of this work is to develop and test a photovoltaic retinal prosthesis for restoring sight to patients blinded by degenerative retinal diseases. A silicon photodiode array for subretinal stimulation has been fabricated by a silicon-integrated-circuit/MEMS process. Each pixel in the two-dimensional array contains three series-connected photodiodes, which photovoltaically convert pulsed near-infrared light into bi-phasic current to stimulate nearby retinal neurons without wired power connections. The device thickness is chosen to be 30 mu m to absorb a significant portion of light while still being thin enough for subretinal implantation. Active and return electrodes confine current near each pixel and are sputter coated with iridium oxide to enhance charge injection levels and provide a stable neural interface. Pixels are separated by 5 mu m wide trenches to electrically isolate them and to allow nutrient diffusion through the device. Three sizes of pixels (280, 140 and 70 mu m) with active electrodes of 80, 40 and 20 mu m diameter were fabricated. The turn-on voltages of the one-diode, two-series-connected diode and three-series-connected diode structures are approximately 0.6, 1.2 and 1.8 V, respectively. The measured photo-responsivity per diode at 880 nm wavelength is similar to 0.36 A W-1, at zero voltage bias and scales with the exposed silicon area. For all three pixel sizes, the reverse-bias dark current is sufficiently low (