This paper presents a fully integrated photodiode-based low-power and low-mismatch stimulator for a subretinal prosthesis. It is known that a subretinal prosthesis achieves 1600-pixel stimulators on a limited single-chip area that is implanted beneath the bipolar cell layer. However, the high-density pixels cause high power dissipation during stimulation and high fabrication costs because of special process technologies such as the complementary metal-oxide semiconductor CMOS image sensor process. In addition, the many residual charges arising from the high-density pixel stimulation have deleterious effects, such as tissue damage and electrode corrosion, on the retina tissue. In this work, we adopted a switched-capacitor current mirror technique for the single-pixel stimulator (SPStim) that enables low power consumption and low mismatch in the subretinal device. The customized P+/N-well photodiode used to sense the incident light in the SPStim also reduces the fabrication cost. The 64-pixel stimulators are fabricated in a standard 0.35-μm CMOS process along with a global digital controller, which occupies a chip area of 4.3 × 3.2 mm2 and are ex-vivo demonstrated using a dissected pig eyeball. According to measured results, the SPStim accomplishes a maximum biphasic pulse amplitude of 143 μA, which dissipates an average power of 167 μW in a stimulation period of 5 ms, and an average mismatch of 1.12 % between the cathodic and anodic pulses.
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机译：本文提出了一种用于视网膜下假体的完全集成的基于光电二极管的低功率和低失配刺激器。众所周知，视网膜下假体在植入双极细胞层下方的有限的单芯片区域上实现了1600像素的刺激器。然而，由于诸如互补金属氧化物半导体CMOS图像传感器工艺之类的特殊工艺技术，高密度像素在刺激期间导致高功率耗散以及高制造成本。另外，由高密度像素刺激产生的许多残余电荷对视网膜组织具有有害作用，例如组织损伤和电极腐蚀。在这项工作中，我们为单像素刺激器（SPStim）采用了开关电容器电流镜技术，该技术可实现视网膜下装置的低功耗和低失配。用于感测SPStim中入射光的定制P + / N阱光电二极管还降低了制造成本。 64像素的刺激器采用标准的0.35μmCMOS工艺以及全局数字控制器制造而成，该控制器占用的芯片面积为4.3×3.2 mm 2 ，并通过解剖猪进行了体外演示。眼球。根据测量结果，SPStim的最大双相脉冲振幅为143μA，在5 ms的激励周期内平均功耗为167μW，阴极和阳极脉冲之间的平均失配为1.12％。
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