Thin-Sized Brain-Computer Interface Robot Based on PNIPAM Hydrogel

Abstract

Electroencephalogram (ECoG) is a neural interface designed to record brain surface activity. It consists of a series of electrodes, with the electrode array capable of recording a large area from the cortical surface. However, traditional ECoG electrode implantation typically requires a craniotomy, and the skull window needed for implantation is often larger than the electrode itself. This results in increased damage to the skull, higher surgical risk, and greater challenges in postoperative care. In order to solve this problem, this project combines flexible film electrodes with intelligent 4D hydrogel materials, and proposes a design scheme of minimally invasive implantable ultra-thin electrodes based on the natural gap between the biological brain and the dura mater. The electrode is fabricated using the MEMS lithography process. The diameter of the electrode dots is 200 µm, the width of the electrode lines is 20 µm, and the overall thickness is approximately 50 µm. The packaging layer is composed of a 4D hydrogel material. The shrinkage, which can range from 29.34% to 88.97%, is achievable depending on the material ratios. This material exhibits self-crimping characteristics, enabling adaptive bonding of the electrode to the detection surface. This design aims to enable minimally invasive implantation of neural electrodes, which can not only reduce the risk of surgery, but also reduce the trauma to patients, and provide a new idea and method for the development of neural interface technology.