A CMOS-based highly scalable flexible neural electrode interface

Abstract

Perception, thoughts, and actions are encoded by the coordinated activity of large neuronal populations spread over large areas. Using thin film electrocorticography (ECoG) arrays, this cortical activity has been used to decode speech and individual finger movements, enabling neuroprosthetics, and to localize epileptic foci. However, the connectorization of these multi-thousand channel thin-film arrays to external circuitry is challenging; current state-of-the-art methods are complex, bulky, and unscalable. We address this shortcoming by developing an electrode connector based on an ultra-conformable thin film electrode array that self-assembles onto hard silicon chip sensors, such as microelectrode arrays (MEAs) or camera sensors enabling large channel counts at high density. The interconnects are formed using microfabricated electrode pads suspended by thin support arms, termed flex2chip. Capillary-assisted assembly drives the pads to deform towards the chip surface, and van der Waals forces maintain this deformation, establishing mechanical and Ohmic contact onto individual pixels. We demonstrate a 2200-channel array with a channel density of 272 channels / mm2 connected to the MEA through the flex2chip interconnection method. Thin film electrode arrays connected through the flex2chip successfully measured extracellular action potentials ex vivo. Furthermore, in a transgenic mouse model for absence epilepsy, Scn8a+/-, we observed highly variable propagation trajectories at micrometer scales, even across the duration of a single spike-and-wave discharge (SWD).

Ultra-flexible endovascular probes for brain recording through micron-scale vasculature

“…First, as MEV implantation induces minimal immune response, future efforts will be directed toward developing stretchable MEV probes with chronic recording capabilities. Second, the platform could be scaled to hundreds to thousands of electrodes for high-density recording and stimulation ( 16, 45 ) by adapting highly scalable I/O interfaces ( 46 ). Third, steering compartments, such as magnetic actuators ( 18, 47 ), could be incorporated to the tip of the probe to control navigation and improve the branch selectivity.…”

Electrochemical and electrophysiological considerations for clinical high channel count neural interfaces

“…(a) Representative positioning of the different electrode types (surface electrocorticography [ECoG], depth, and penetrating surface) on the surface of the brain (illustrations not to scale). (b) Comparison of the inter-contact pitch, total coverage, and channel count offered by the state-of-the-art recording electrodes: 1-PtNRGrids, 33 2-Utah Array, 31 3-Neuropixels, 32 4-Neural Matrix, 42 5-Paradromics Argo, 36 , 43 6-NeuroGrid, 44 7-Viventi, 45 8-Escabi, 46 9-Ledochowitsch, 47 10-Molina-Luna, 48 11-Hollenberg, 49 12-Rubehn, 50 13-Kaiju, 51 14-Matsuo, 52 15-Toda, 53 16-Castagnola, 54 17-Zhao, 55 18- Precision Neuroscience, 56 19-Ad-Tech Medical Clinical Grid, 20-PMT Corporation Clinical Grid. 57 The dashed region shows the tradeoff between the channel pitch and coverage for devices with limited channel count.…”

“…Yet, high spatial resolution electrodes such as the Utah array and the Neuropixels probes can reach high channel counts up to a few thousand contacts for a relatively small coverage area ( Figure 1b ). 31 , 32 To mitigate this tradeoff, new fabrication and interconnection strategies evolved to achieve thousands 33 – 35 to tens of thousands 36 of electrode channels in a variety of species, including humans. 37 …”

2D Optimized Electrodes for Highly Sensitive and Biocompatible Neural Recording

“…Neural electrodes, as devices for recording and stimulating neural activity, are crucial components for establishing connections between the human brain and the external world. 1,2 They enable high-precision and wide-range recording of neuronal discharge patterns and can be used to modulate neuronal activity through electrical stimulation, offering potential for alleviating and treating neurological disorders, 3−5 holding immense potential for treating neurological disorders. 6,7 Implantable neural electrodes invade the brain directly without filtering through the cortex and skull, thus providing high spatial resolution and signal-to-noise ratio (SNR) for signal transmission.…”