Optoelectronic retinal prosthesis: system design and performance
Optoelectronic retinal prosthesis: system design and performance
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DOI：
10.1088/1741-2560/4/1/s09
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发表时间：
2007-03-01
影响因子：
4
通讯作者：
Palanker, D. V.
中科院分区：
文献类型：
--
作者：
Loudin, J. D.;Simanovskii, D. M.;Palanker, D. V.
高分辨率视网膜假体的设计提出了许多独特的工程和生物挑战。越来越小的电极必须注入足够的电荷来刺激神经细胞，在电化学安全电压范围内。刺激部位应放置在距离靶细胞的电极直径内，以防止“模糊”并最大限度地减少电流。信号必须通过无线方式从外部源传递到大量电极，理想情况下，视觉信息应该保持与眼球运动的自然联系。最后，一个好的系统必须具有广泛的刺激电流，图像处理的外部控制和阳极优先或阴极优先脉冲的选择。本文讨论了这些挑战，并提出了解决方案，他们的系统的基础上，光电二极管阵列注入。视频帧通过以近红外波长运行的头戴式近眼投影系统进行处理并成像到视网膜植入物上。光电二极管将光转换成脉冲电流，通过施加共同的双相偏置波形来使电荷注入最大化。由此产生的假体将在中央10度视野中以高达50 Hz的帧速率提供刺激，通过眼球运动可获得完整的30度视野。像素大小可从100 μ m扩展到25 μ m，对应于直径为3 mm的植入物上的640-10 000个像素。
The design of high-resolution retinal prostheses presents many unique engineering and biological challenges. Ever smaller electrodes must inject enough charge to stimulate nerve cells, within electrochemically safe voltage limits. Stimulation sites should be placed within an electrode diameter from the target cells to prevent 'blurring' and minimize current. Signals must be delivered wirelessly from an external source to a large number of electrodes, and visual information should, ideally, maintain its natural link to eye movements. Finally, a good system must have a wide range of stimulation currents, external control of image processing and the option of either anodic-first or cathodic-first pulses. This paper discusses these challenges and presents solutions to them for a system based on a photodiode array implant. Video frames are processed and imaged onto the retinal implant by a head-mounted near-to-eye projection system operating at near-infrared wavelengths. Photodiodes convert light into pulsed electric current, with charge injection maximized by applying a common biphasic bias waveform. The resulting prosthesis will provide stimulation with a frame rate of up to 50 Hz in a central 10 degrees visual field, with a full 30 degrees field accessible via eye movements. Pixel sizes are scalable from 100 to 25 mu m, corresponding to 640-10 000 pixels on an implant 3 mm in diameter.