2, Osaka University, Osaka, , Japan
3, National Institute of Information and Communications Technology, Osaka, , Japan
4, Kyushu University, Fukuoka, , Japan
The present work reports effective methods that enabled neural interfaces to stabilize monitoring electrocorticogram (ECoG) on a rodent for 2 months. Integration of metal-nanowire-based tracks that showed high optical transparency and stretchability facilitated a simultaneous optogenetic stimulation and ECoG monitoring in vivo.
Neural interface monitoring and manipulating a target neural activity have realized versatile approaches in neurology [1, 2]. Specific example is a contribution on brain machine interfaces (BMIs)  with a feedback sensation. The bifunctional neural interface is also considered on genetic diagnoses and therapies of patients who suffers from intractable diseases. Such neural interfaces have been demanded to keep their function under long-term implantation, however, usually face on granulation tissue  that interrupts the access to the targeted neuron.
Here, we report highly stable neural interfaces integrated with transparent and stretchable metal-nanowire-based tracks. Au-plated Ag-nanowire-based (AgNW/Au) tracks were connected to 16-channel-microelectrode and encapsulated in thin polymer substrate. The microelectrode was fabricated with gel materials which endured over 2 months immersion in saline solution. Moreover, the AgNW/Au tracks that showed optical transparency over 70%, mechanical durability over 50% strain, and electrical reliability in the presence of water; Ag-nanowire plated with a noble metal increased track’s performance from pristine Ag-nanowire-based tracks without a significant loss of transparency. The transparent neural interface stabilized mechanically, electrically, and chemically realized in long-term implantation by the mean of an antithrombogenic polymer treatment. The sufficient optical transparency also achieved a simultaneous optogenetic stimulation and ECoG monitoring, indicating to open a way of multifaceted approaches for translational research.
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