Zappitelli, K. M. | bioRxiv Science

bioRxiv2024

Optogenetic stimulation of a cortical biohybrid implant guides goal directed behavior

Brain-computer interfaces (BCIs) hold exciting therapeutic potential, but tissue damage caused by probe insertion limits channel count. Biohybrid devices, in which the cell-device interface is crafted in the laboratory, hold promise to address this limitation, but these devices have lacked a demonstration of their applicability for BCI. We developed a biohybrid approach to engraft optogenetically-enabled neurons on the cortical surface housed in a 2D-scaffold of circular microwells. The engrafted neurons survived, exhibited spontaneous activity, and integrated with the host brain several weeks after implantation. We then trained mice with biohybrid implants to perform an optical stimulation task and showed that they could effectively report optogenetic stimulation of their neural graft. This demonstration shows that a cortical biohybrid implant can be used to transmit information to the brain of an implanted animal.

neuroscience↗

bioRxiv2022

Direct laser writing of 3D electrodes on flexible substrates

This report describes a 3D microelectrode array integrated on a thin-film flexible cable for neural recording in small animals. The micro electrode array fabrication process integrates traditional silicon thin-film processing techniques and direct laser writing of 3D structures at micron resolution via two-photon lithography. While direct laser writing of 3D printed electrodes has been described before, this report is the first to provide a method for high-aspect-ratio laser-written structures integrated with microfabricated electrical traces. One prototype is a 16-channel array composed of 350 m long shanks spaced on a grid with 90 m pitch. Other devices shown here include biomimetic mosquito-needles that penetrate through the dura of birds and porous electrodes designed to promote tissue ingrowth or enhance charge injection capacity for neural stimulation. These devices are just a few examples of a new design space that will enable high-channel-count 3D electrode arrays with features definable at single micrometer resolution. Using a custom laser writer, the 3D printing process is rapid (1 mm3/min). This high-speed printing combined with standard wafer-scale processes will enable efficient device fabrication and new studies examining the relationship between electrode geometry and electrode performance. We anticipate highest impact in small animal models, nerve interfaces, retinal implants, and other applications requiring small, high density 3D electrodes.

bioengineering↗