Mechanically adaptive and deployable intracortical probes enable long-term neural electrophysiological recordings

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 121; no. 40; p. e2403380121
• Main Authors: Wang, Suhao, Jiang, Qianqian, Liu, Hang, Yu, Chaonan, Li, Pengxian, Pan, Gang, Xu, Kedi, Xiao, Rui, Hao, Yaoyao, Wang, Chengjun, Song, Jizhou
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 01.10.2024
• Subjects: Animals; Brain; Brain - physiology; Cerebral Cortex - physiology; Configuration management; Design; Electrodes; Electrodes, Implanted; Electrophysiological Phenomena; Fabrication; Immune response; Immunological memory; Implantation; Mechanical properties; Neurons - physiology; Phase transitions; Polymers; Polymers - chemistry; Probes; Rats; Rats, Sprague-Dawley; Recording; Shape memory; Softening; Structural design; Structural engineering; Substrates; Tissues; neural probe; mechanically adaptive; shape memory polymer; deployable structure
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.2403380121

Flexible intracortical probes offer important opportunities for stable neural interfaces by reducing chronic immune responses, but their advances usually come with challenges of difficult implantation and limited recording span. Here, we reported a mechanically adaptive and deployable intracortical probe, which features a foldable fishbone-like structural design with branching electrodes on a temperature-responsive shape memory polymer (SMP) substrate. Leveraging the temperature-triggered soft-rigid phase transition and shape memory characteristic of SMP, this probe design enables direct insertion into brain tissue with minimal footprint in a folded configuration while automatically softening to reduce mechanical mismatches with brain tissue and deploying electrodes to a broader recording span under physiological conditions. Experimental and numerical studies on the material softening and structural folding-deploying behaviors provide insights into the design, fabrication, and operation of the intracortical probes. The chronically implanted neural probe in the rat cortex demonstrates that the proposed neural probe can reliably detect and track individual units for months with stable impedance and signal amplitude during long-term implantation. The work provides a tool for stable neural activity recording and creates engineering opportunities in basic neuroscience and clinical applications.