Microgaskets for High-Channel-Density Reconnectable Implantable Packaging

• Published in: Journal of microelectromechanical systems Vol. 31; no. 3; pp. 384 - 392
• Main Authors: Rustogi, Paritosh, Judy, Jack W.
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.06.2022; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Aspect ratio; Bioelectricity; channel isolation; Clamps; Connectors; Contacts; Density; Elastomers; Gaskets; Impedance; Implantable connectors; Implants; microgaskets; neural interfaces; Polydimethylsiloxane; Surface impedance; Microgaskets; Channel Isolation; Neural interfaces; Implantable Connectors
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2022.3159487

Demands for implantable bioelectronic devices to increase the number of channels for greater functional capacity and resolution, shrink implant size to minimize tissue response and patient burden, and support battery changes and electronics upgrades for long-term operational viability, cannot be met with existing implant-connector technology. In this paper we describe our novel approach to develop a rematable high-channel-density implant-connector technology, with a focus on the design, fabrication, and characterization of its microgasket. The microgaskets made of polydimethylsiloxane elastomer (PDMSe) have achieved much better electrical isolation for neural stimulation (~5 <inline-formula> <tex-math notation="LaTeX">\text{M}\Omega </tex-math></inline-formula> at 10 kHz) compared with conventional implant connectors (50 <inline-formula> <tex-math notation="LaTeX">\text{k}\Omega </tex-math></inline-formula> at 10 kHz), despite a 200-fold increase in channel density (conventional: ~0.0644 ch/mm 2 , microgasket: ~12.8 ch/mm 2 ). The microgaskets also achieved high electrical isolation for neural recording (i.e., ~35 <inline-formula> <tex-math notation="LaTeX">\text{M}\Omega </tex-math></inline-formula> at 1 kHz) at the same high channel density. When mechanically compressed the microscale vias in the PDMSe microgaskets deform laterally, which could damage or enhance gasket-traversing conductive spring elements in each microscale via depending on their design. We have demonstrated that by lowering the height-to-width aspect ratio of the gasket vias, they can maintain their shape under clamping pressures high enough to achieve high isolation. [2021-0024]