A Translational Platform for Polyimide Neural Interfaces: Polyimide Synthesis and in Vivo Evaluation in Epileptic Mice.

Abstract

Thin-film polyimide neural probes have shown great promise in neuroscience but remain difficult to clinically translate due to the unavailability and lack of customizability of commercially available medical-grade polyamic acids. We present an open-source, end-to-end platform for synthesizing BPDA-pPDA-based polyimide from a custom polyamic acid and translating it into microfabricated thin-film neural interfaces. The approach combines accessible polymer chemistry with a streamlined MEMS-compatible fabrication process to produce flexible, biocompatible depth and surface electrode arrays with high thermal stability, chemical inertness, and low moisture uptake. Devices were validated through benchtop characterization, ISO 10993-11 systemic toxicity testing, and in vivo electrophysiology, both acute and semi-chronic, in wild-type and laforin knockout epileptic mice. The arrays reliably captured high-quality multi- and single-unit activity, as well as spontaneous epileptiform discharges, over implantation periods of up to 12 days. By demonstrating a customizable, end-to-end platform for synthesizing and fabricating thin-film polyimide neural electrodes, and by mimicking human neurosurgical workflows through depth, surface, and semi-chronic studies in mice, this work underscores the translational potential of polyimide-based neural microelectrodes and provides a practical pathway to accelerate clinical adoption.