Microneedle Penetrating Array with Axon-Sized Dimensions for Cuff-less Peripheral Nerve Interfacing

• Main Authors: Yan, Dongxiao, Jiman, Ahmad, Ratze, David, Huang, Shuo, Parizi, Saman, Welle, Elissa, Ouyang, Zhonghua, Patel, Paras, Kushner, Mark J., Chestek, Cynthia, Bruns, Tim M., Yoon, Euisik, Seymour, John
• Format: Conference Proceeding
• Language: English
• Subjects: Etching; Needles; Plasmas; Shafts; Shape; Silicon; Stress
• ISSN: 1948-3554
• DOI: 10.1109/NER.2019.8717097

Autonomic nerves are typically only hundreds of microns in diameter near their organ targets and these carry all of the sympathetic and parasympathetic control signals. We present a cuff-less microneedle array specifically designed to potentially map small autonomic nerves. The focus of this paper is the design and fabrication of an ultra-miniaturized silicon needle array on a silicone substrate. We demonstrate arrays having 25 to 100 microneedles. Each needle has a 1-micron tip and dual-taper shaft. We demonstrate an ability to control the tip shape, angle, and shaft angle which is important for balancing sharpness and stiffness. These high-density arrays also include a special backside anchor embedded in silicone for stability in the elastic substrate, yet the array freely wraps over a 300-µm nerve. Another critical method presented here is a surgical technique for inserting and securing an array without a cuff (as small as 0.3 mm wide and 1.2 mm long) by photochemical bonding of collagen/Rose Bengal adhesive agents to epineurium. Future work will focus on device functionalization and histological characterization in a rat vagus model.