Ultraflexible and Stretchable Intrafascicular Peripheral Nerve Recording Device with Axon‐Dimension, Cuff‐Less Microneedle Electrode Array

作者：Yan Dongxiao; Jiman Ahmad A.; Bottorff Elizabeth C.; Patel Paras R.; Meli Dilara; Welle Elissa J.; Ratze David C.; Havton Leif A.; Chestek Cynthia A.; Kemp Stephen W. P.; Bruns Tim M.; Yoon Euisik; Seymour John P.

来源：Small, 2022, 18(21).

DOI：10.1002/SMLL.202200311

• bioelectronics
• intrafascicular recordings
• microelectrode arrays
• microneedles
• neural interfaces, peripheral nerves
• tissue reactivity

Peripheral nerve mapping tools with higher spatial resolution are needed to advance systems neuroscience, and potentially provide a closed‐loop biomarker in neuromodulation applications. Two critical challenges of microscale neural interfaces are 1) how to apply them to small peripheral nerves, and 2) how to minimize chronic reactivity. A flexible microneedle nerve array (MINA) is developed, which is the first high‐density penetrating electrode array made with axon‐sized silicon microneedles embedded in low‐modulus thin silicone. The design, fabrication, acute recording, and chronic reactivity to an implanted MINA, are presented. Distinctive units are identified in the rat peroneal nerve. The authors also demonstrate a long‐term, cuff‐free, and suture‐free fixation manner using rose bengal as a light‐activated adhesive for two time‐points. The tissue response is investigated at 1‐week and 6‐week time‐points, including two sham groups and two MINA‐implanted groups. These conditions are quantified in the left vagus nerve of rats using histomorphometry. Micro computed tomography (micro‐CT) is added to visualize and quantify tissue encapsulation around the implant. MINA demonstrates a reduction in encapsulation thickness over previously quantified interfascicular methods. Future challenges include techniques for precise insertion of the microneedle electrodes and demonstrating long‐term recording.(#br)An ultrasmall microneedle nerve array is developed for mapping of peripheral nerves. Isotropic and anisotropic reactive etching shape each electrode. This process allows the inclusion of high‐temperature silicon dioxide insulation and a compliant medical‐grade elastomer substrate. The cuff‐less nerve interface is attached to autonomic nerves in vivo using photochemical activation. The results demonstrate fabrication, acute electrophysiology, and high‐fidelity device‐tissue interfaces.