Lee Seung Woo, Seo Jong-Mo, Ha Seungmin, Kim Eui Tae, Chung Hum, Kim Sung June
School of Electrical Engineering and Computer Science, Seoul National University College of Medicine, Gwanak-gu, Korea.
Invest Ophthalmol Vis Sci. 2009 Dec;50(12):5859-66. doi: 10.1167/iovs.09-3743. Epub 2009 Jun 24.
To develop a liquid crystal polymer (LCP)-based, long-term implantable, retinal stimulation microelectrode array using a novel fabrication method.
The fabrication process used laser micromachining and customized thermal-press bonding to produce LCP-based microelectrode arrays. To evaluate the fabrication process and the resultant electrode arrays, in vitro reliability tests and in vivo animal experiments were performed. The in vitro tests consisted of electrode site impedance recording and electrode interlayer adhesion monitoring during accelerated soak tests. For in vivo testing, the fabricated electrode arrays were implanted in the suprachoroidal space of rabbit eyes. Optical coherence tomography (OCT) and electrically evoked cortical potentials (EECPs) were used to determine long-term biocompatibility and functionality of the implant.
The fabricated structure had a smooth, rounded edge profile and exhibited moderate flexibility, which are advantageous features for safe implantation without guide tools. After accelerated soak tests at 75 degrees C in phosphate-buffered saline, the electrode sites showed no degradation, and the interlayer adhesion of the structure showed acceptable stability for more than 2 months. The electrode arrays were safely implanted in the suprachoroidal space of rabbit eyes, and EECP waveforms were recorded. Over a 3-month postoperative period, no chorioretinal inflammation or structural deformities were observed by OCT and histologic examination.
LCP-based flexible microelectrode arrays can be successfully applied as retinal prostheses. The results demonstrate that such electrode arrays are safe, biocompatible, and mechanically stable and that they can be effective as part of a chronic retinal implant system.
采用一种新颖的制造方法，开发一种基于液晶聚合物（LCP）的、可长期植入的视网膜刺激微电极阵列。
制造过程采用激光微加工和定制热压键合来生产基于LCP的微电极阵列。为评估制造过程和所得电极阵列，进行了体外可靠性测试和体内动物实验。体外测试包括在加速浸泡测试期间记录电极位点阻抗和监测电极层间粘附力。对于体内测试，将制造的电极阵列植入兔眼的脉络膜上腔。使用光学相干断层扫描（OCT）和电诱发皮层电位（EECP）来确定植入物的长期生物相容性和功能。
制造的结构具有光滑、圆形的边缘轮廓，并表现出适度的柔韧性，这对于无需引导工具即可安全植入是有利的特征。在75摄氏度的磷酸盐缓冲盐水中进行加速浸泡测试后，电极位点没有降解，结构的层间粘附力在超过2个月的时间内表现出可接受的稳定性。电极阵列被安全地植入兔眼的脉络膜上腔，并记录到了EECP波形。在术后3个月的时间里，通过OCT和组织学检查未观察到脉络膜视网膜炎症或结构畸形。
基于LCP的柔性微电极阵列可成功应用于视网膜假体。结果表明，这种电极阵列是安全的、生物相容的且机械稳定的，并且作为慢性视网膜植入系统的一部分可以是有效的。
