For patients to benefit from state-of-the-art high-channel-count neural-interface technology, translatable implant packaging technology is needed to support it. Despite advances in implant electronics, batteries, enclosures, and even high-feedthrough-count and high-feedthrough-density headers, the lack of advancement in implant connector technology has imposed an often-unacceptable tradeoff between high interface channel count and the ability to disconnect and reconnect implanted interface leads from packaged and implanted electronics. Specifically, it would be of great value to enable battery changes, implant electronics replacement, or implant electronics upgrades to be performed without disturbing high-channel-count thin-film interfaces that have become integrated into delicate and sensitive neural tissue. We propose to revolutionize implantable connector technology by creating miniature, reliable, and high-channel-density connectors for high-channel-count neural interfaces produced with thin-film microfabrication technology. To do this we will advance and miniaturize three critical connector components: (1) the gaskets used to reliably achieve and maintain high channel density and channel-to-channel isolation even without hermeticity; (2) the conductive spring elements in each via used to reliably achieve and maintain low-resistance contacts; and (3) a compact and easy-to-use mechanical mechanism to achieve and maintain a high-clamping force for sealing to the gasket and engaging the conductive springs between all contacts. In Specific Aim 1 we propose to develop and characterize the performance and reliability of a miniaturized thin-film implant-gasket technology so that higher channel densities are possible in implantable connectors without compromising channel-to-channel isolation. In Specific Aim 2 we propose to develop and characterize the performance and reliability of multi-point low-impedance electrical contacts between high-channel-density interface leads and high-feedthrough-density implant-packaging headers. To mitigate risk, we will explore three different approaches. First, we will pattern gaskets or fill gasket vias with a dense mixture of conductive metal particles and PDMS. Second, inspired by the mm-scale packaging technology called fuzz buttons, we will microfabricate fuzz buttons that consist of a dense mat of electrospun microfibers that can be patterned directly on top of the Pt vias in the ceramic header, pyrolyzed, and then coated with metal. Third, we will microfabricate multiple stress-engineered upward-curling microcantilever springs on top of each feedthrough of the ceramic-Pt substrate. Each approach is designed to achieve multiple points of contact for low impedance and a restoring spring force to maintain electrical connection spanning the gasket over time. In Specific Aim 3 we propose to develop and characterize the performance and reliability of the clamping mechanism needed to deliver enough force to achieve reliable channel-to-channel isolation and low contact impedance. For each aim we will use an aggressive reactive-accelerated-aging soak test that mimics a strong tissue response to challenge the reliability of each component of the advanced implantable connector.
