Forssell Mats, Ong Xiao Chuan, Khilwani Rakesh, Burak Ozdoganlar O, Fedder Gary K
Department of Electrical and Computer Engineering, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA, 15213, USA.
Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA.
Biomed Microdevices. 2018 Jul 26;20(3):61. doi: 10.1007/s10544-018-0307-3.
The long-term electrical leakage performance of parylene-C/platinum/parylene-C (Px/Pt/Px) interconnect in saline is evaluated using electrochemical impedance spectroscopy (EIS). Three kinds of additional ceramic encapsulation layers between the metal and Px are characterized: 50 nm-thick alumina (AlO), 50 nm-thick titania (TiO), and 80 nm-thick AlO-TiO nanolaminate (NL). The AlO and TiO encapsulation layers worsen the overall insulation properties. The NL encapsulation layer improves the insulation when combined with a TiO outer layer to promote adhesion to the Px. Experiments are performed with various insulation promotion treatments: A-174 silane (A174) treatment before Px deposition (to promote adhesion); SF plasma treatment (F) after Px deposition (to increase hydrophobicity); and ion-milling descum (IM) after Px deposition (to prevent parylene oxidation). A174 and F treatments do not have a significant impact, while IM leads to worse insulation performance. A circuit model elucidates the insulation characteristics of Px-ceramic-Pt-ceramic-Px interconnect. These studies provide a foundation for processing ultra-compliant neural probes with long-term chronic utility.
采用电化学阻抗谱（EIS）评估聚对二甲苯-C/铂/聚对二甲苯-C（Px/Pt/Px）互连在盐水中的长期漏电性能。对金属与Px之间的三种附加陶瓷封装层进行了表征：50纳米厚的氧化铝（AlO）、50纳米厚的二氧化钛（TiO）以及80纳米厚的AlO-TiO纳米层压板（NL）。AlO和TiO封装层会恶化整体绝缘性能。NL封装层与TiO外层结合时可改善绝缘性能，以促进与Px的粘附。对各种绝缘促进处理进行了实验：在沉积Px之前进行A-174硅烷（A174）处理（以促进粘附）；在沉积Px之后进行SF等离子体处理（F）（以增加疏水性）；以及在沉积Px之后进行离子铣削去渣（IM）（以防止聚对二甲苯氧化）。A174和F处理没有显著影响，而IM会导致绝缘性能变差。一个电路模型阐明了Px-陶瓷-Pt-陶瓷-Px互连的绝缘特性。这些研究为处理具有长期慢性效用的超柔性神经探针奠定了基础。
