Novel flexible neural interfaces: intracortical reconfigurable multimodal origami probe and intrafascicular microneedle electrode array

Flexible neural interface is an emerging technology that enables high-spatial-resolution neural recording with enhanced biocompatibility in central and peripheral nervous systems. The dissertation is dedicated to tackling various challenges in channel-count scaling, multi-function integration, three-dimensional electrode array formation, and tissue-reactivity mitigation with innovative designs and technologies. Specifically, it is divided into four parts: I. Chronic implantable thin-film polyimide based flexible neural probe. II. Reconfigurable and multimodal flexible neural probes by magnetic- and capillary-assisted hybrid self-assembly. III. Origami neural probes with 360° or double-side distributed electrode array by capillary-assisted self-assembly. IV. Flexible microneedle electrode array for interfascicular recording of sub-millimeter nerves. In the second part, micro-magnet “LEGO”s were embedded into the flexible probes allowing separately fabricated probes to be self-assembled into one. A flexible probe with over 128 electrodes integrated with temperature and chemical sensors was created which has by far the highest single-shank channel count. In the third part, a 3D origami probe with up to 128 electrodes and a diameter of 105-μm was created which has by far the highest density 360° distributed microelectrodes. Angular heterogeneous single-unit signals and neural connectivity surrounding the probe were identified. In the last part, axon-dimension microneedle electrodes were shaped with reactive ion etching and embedded into a thin silicone substrate. Intrafascicular recording and reduced tissue encapsulation were demonstrated.

Chair: Professor Euisik Yoon