Understanding brain function requires the ability to record simultaneously from thousands or tens-of- thousands of neurons contributing to the dynamic activity in a neural circuit. CMOS based electrode technology constitutes the only means to electrically interact with living systems beyond this scale and at sub- millisecond time resolution, but suffers from the limited recording depth and the invasiveness of silicon wafer which might prohibit their use in human experimentation. Still, there is a growing awareness that leveraging commercially available large-scale CMOS technologies might address the scaling challenge in brain mapping. We herein propose a new device concept which encompasses a unique and innovative combination of two widely-used existing technologies - metal microwires and CMOS electronics - to create a synergistic result. By developing small-diameter, deep-penetrating, gold microprobes monolithically on a thin yet reliable CMOS electronic ?router?, we aim to achieve over one thousand subcellular neuro probes with only a few I/O wires in a commercially viable way, with scalability up to tens of thousands and even higher for large-scale in vivo brain mapping. We will first develop a viable electrochemical deposition process to achieve high-aspect-ratio gold microprobes with down to 10m diameter, and up to 1mm length. A passive gold microprobe array with 96 channels will be developed first at a density up to 100 probes/mm2. In parallel, we will develop a massively multiplexed CMOS ASIC design on SOI substrates to be thinned down to the buried oxide layer with less-than- 3m device thickness on a supporting Kapton substrate. We will form the massively multiplexed penetrating arrays with up to 1000 electrodes by synthesizing gold microprobes on the thinned-down ASIC. Implantations in rodent cortex will be used to assess recording reliability and tissue response. The monolithic fabrication process of the gold microprobes will support up-scaling to 10,000 - 100,000 microprobes or higher at the cm scale. This project leverages a vibrant collaboration between material scientists, circuit designers, device engineers and electrophysiologists at Northeastern University (NU) and the University of Utah (Utah), to realize large-scale, subcellular, deep-penetrating gold microprobe arrays that serve as a basis to scale to whole- mouse-brain recording.
To understand how the brain works and cure brain diseases, neuroscientists and clinicians need brain-mapping devices. This project will develop new device concepts to enable ultra-large-scale introcortical electrode arrays, which can measure neural signals with high resolution but also over large areas of the brain. The devices here also have the potential to be chronically implanted, to improve the performance of auditory, visual and motor prosthetics.
