(355e) Flexible Gallium-Based PEDOT:BF4 Coated Electrodes for Chronic Neural Recording and Biocompatibility

Implantable microelectrode arrays are valuable tools in neuroscience for studying neural functionalities and disorders like Parkinson's, epilepsy, and spinal cord injury. However, rigid-metal-based electrode arrays often face challenges due to mechanical mismatches with brain tissue, leading to chronic inflammatory responses and compromised performance. To address this, we propose using gallium-based electrodes, offering minimal cytotoxicity, excellent electrical conductivity, and mechanical properties suitable for brain tissue. The low melting point of gallium allows it to transition into liquid after insertion, minimizing tissue-device mismatch.

Our study presents a flexible, gallium-based, PEDOT: BF4-coated neural array for chronic in vivo applications. Compared to rigid metal arrays, our gallium-based neuro devices demonstrate improved biocompatibility, as evidenced by reduced neuron death around the electrode implantation site in rat brains after eight weeks. We detail the fabrication process, including electrode fabrication, customizable array assembly, and PEDOT: BF4 deposition.

We characterize the electrochemical properties, thermal stability, and morphology of the PEDOT: BF4-coated gallium electrodes, showing their structural integrity and chronic electrochemical stability in vitro over five weeks. Acute in vitro and in vivo studies validate the action potential recording capabilities of the flexible gallium-based neuro device.

Furthermore, our chronic implantation study in rats showed that our devices maintained electrochemical functionality over eight weeks. Post-implantation analysis also reveals reduced inflammation GFAP markers and closer proximity of NeuN neuronal markers to the electrode site than rigid metal implants, suggesting enhanced biocompatibility and minimized tissue damage with our gallium-based, PEDOT: BF4-coated neural implant.