(355b) All-Polymer-Based Configurable Intracortical Neural Electrode Array for Chronic In Vivo Brain Neural Recording

Implantable neural electrode arrays are promising bioelectronic platforms for recording electrophysiological signals from brains with high precision. However, most commercial electrode arrays have a large mechanical mismatch with the brain tissue and offer limited configuration due to material choices and conventional semiconductor fabrication processes. The development of next-generation tissue-compliant electrode arrays requires the convergence of advanced fabrication processes and novel bioelectrically active materials. In this study, we introduce the concept of integrating advanced two-photon 3D-printed technology and tailored conductive polymer electrodeposition to create the first functional all-polymer electrode arrays. The two-photon 3D printing technology is used to create 3D-printed microchannels to configure neural electrode arrays on demand. Then, an optimized conductive polymer deposition protocol (poly(3,4-ethylenedioxythiophene) doped with tetrafluoroborate (PEDOT:BF₄)) is used to create 3D bioelectrically active materials inside 3D-printed microchannels. These self-assembled PEDOT:BF₄ all polymer neural electrodes can reduce the mechanical mismatch between electrodes and brain tissue.

Moreover, they are electrochemically stable and have low interfacial impedance under physiological conditions. The results of impedance measurements reveal a lower impedance of the PEDOT electrodes than conventional metal and semiconductor electrodes. A chronic animal study (6 weeks) was also implemented to conduct electrophysiology recording experiments in free-moving animals. The chronic electrophysiology experiments have demonstrated stable recording of single-unit neural activities over 6 weeks. This is the first demonstration of chronically functional all-polymer intracortical neural electrode arrays for single-unit neural recording. These results indicate that the 3D-printed neural arrays based on templated PEDOT:BF₄ are a promising next-generation bioelectronic platform for intracortical recording of electrophysiological signals. Moreover, the numerous designs available through 3D printing offer opportunities to go beyond the current neural array technology.