One-year evaluation of a 128-channel flexible IrOx neural interface and development of a miniaturized 256-channel integrated prototype.

Abstract

High-density neural interfaces require both durable electrode-tissue interfaces and compact electronic integration. Here, we combine a year-long evaluation of a 128-channel flexible IrOx electrode array (128-Flex) with the development of a miniaturized 256-channel integrated prototype (256-prot). IrOx modification reduced the mean 1 kHz impedance from 1.096 MΩ to 18.15 kΩ and increased charge storage capacity from 2.02 to 15.37 mC/cm2. Periodic in vivo recordings extended to 12 and 7 months in two rabbits, respectively, with final-session mean SNR values of 6.18 and 5.88 among spike-detecting channels. Post-explantation characterization of the 12-month device showed retained electrode morphology and electrochemical functionality, with a mean impedance of 48.60 kΩ and charge storage capacity of 8.67 mC/cm2. Building on this electrode platform, two 128-channel ASIC modules were integrated through a resin-based feedthrough substrate and two BGA interfaces into a 13 × 13 × 3 mm bare module weighing 1.03 g. The prototype recorded LFPs and spike activity at 1.5 months in an independent rabbit, with 80 and 73 effective recording channels in separately acquired module datasets. Enclosure optimization remains a priority for extending integrated-system evaluation. These results support the long-term recording utility of the flexible IrOx interface and the feasibility of the compact integration strategy.

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