Wide bandgap semiconductor nanomembranes as a long-term biointerface for flexible, implanted neuromodulator

• Published in: Proceedings of the National Academy of Sciences - PNAS 2022-08, Vol.119 (33), p.e2203287119
• Main Authors: Nguyen, Tuan-Khoa, Barton, Matthew, Ashok, Aditya, Truong, Thanh-An, Yadav, Sharda, Leitch, Michael, Nguyen, Thanh-Vinh, Kashaninejad, Navid, Dinh, Toan, Hold, Leonie, Yamauchi, Yusuke, Nguyen, Nam-Trung, Phan, Hoang-Phuong
• Format: Article
• Language: English
• Subjects: Animal models; Barrier layers; Bioelectricity; Biological Sciences; Biomedical materials; Carbon Compounds, Inorganic - chemistry; Chemical vapor deposition; Electric Stimulation Therapy - instrumentation; Electrodes; Epilepsy; Fabrication; Flexible components; Implantable Neurostimulators; Mass production; Membranes, Artificial; Microelectromechanical systems; Movement disorders; Muscle contraction; Muscles; Muscular function; Nanostructures; Nervous system; Neurodegenerative diseases; Neurological diseases; Neuromodulation; Parkinson's disease; Peripheral nerves; Physical Sciences; Semiconductors; Service life assessment; Silicon; Silicon carbide; Silicon Compounds - chemistry; Silicon dioxide; Silicon Dioxide - chemistry; Spinal cord injuries; Stability; Stimulation; Thin films; Wet oxidation; Wide bandgap semiconductors
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.2203287119

Electrical neuron stimulation holds promise for treating chronic neurological disorders, including spinal cord injury, epilepsy, and Parkinson's disease. The implementation of ultrathin, flexible electrodes that can offer noninvasive attachment to soft neural tissues is a breakthrough for timely, continuous, programable, and spatial stimulations. With strict flexibility requirements in neural implanted stimulations, the use of conventional thick and bulky packages is no longer applicable, posing major technical issues such as short device lifetime and long-term stability. We introduce herein a concept of long-lived flexible neural electrodes using silicon carbide (SiC) nanomembranes as a faradic interface and thermal oxide thin films as an electrical barrier layer. The SiC nanomembranes were developed using a chemical vapor deposition (CVD) process at the wafer level, and thermal oxide was grown using a high-quality wet oxidation technique. The proposed material developments are highly scalable and compatible with MEMS technologies, facilitating the mass production of long-lived implanted bioelectrodes. Our experimental results showed excellent stability of the SiC/silicon dioxide (SiO ) bioelectronic system that can potentially last for several decades with well-maintained electronic properties in biofluid environments. We demonstrated the capability of the proposed material system for peripheral nerve stimulation in an animal model, showing muscle contraction responses comparable to those of a standard non-implanted nerve stimulation device. The design concept, scalable fabrication approach, and multimodal functionalities of SiC/SiO flexible electronics offer an exciting possibility for fundamental neuroscience studies, as well as for neural stimulation-based therapies.