Multiplexed Surface Electrode Arrays Based on Metal Oxide Thin-Film Electronics for High-Resolution Cortical Mapping

Area of Science:

• Neuroscience
• Biomedical Engineering
• Materials Science

Background:

• Electrocorticography (ECoG) is crucial for brain activity recording in research and clinical settings.
• Existing passive ECoG systems face limitations in spatial resolution, cortical coverage, and system compactness due to individual electrode wiring.
• The electrode count and density are bottlenecked by the need for dedicated wiring for each electrode.

Purpose of the Study:

• To present an active micro-electrocorticography (µECoG) implant overcoming the wiring limitations of traditional ECoG arrays.
• To demonstrate a novel neural interface with high electrode density and wide cortical coverage.
• To enable simultaneous recording from a large number of electrodes with reduced noise.

Main Methods:

• Development of a flexible electrode array incorporating metal oxide thin-film transistors (TFTs).
• Integration of the array with an incremental-ΔΣ readout integrated circuit (ROIC).
• Implementation of a 16:1 time-division multiplexing scheme for addressing multiple electrodes via shared lines.
• In vivo validation in mice, recording spontaneous activity and somatosensory evoked potentials.

Main Results:

• The active µECoG implant successfully recorded neural activity from up to 256 electrodes.
• The system demonstrated lower noise levels compared to existing active µECoG arrays.
• Effective recording over a cortical surface area of approximately 8x8 mm² was achieved in mice.
• The technology overcomes the wiring bottleneck inherent in conventional ECoG systems.

Conclusions:

• The proposed active µECoG neural interface offers a significant advancement over traditional ECoG technology.
• This technology holds promise for enhanced cerebral cortex mapping.
• It serves as an enabling technology for the development of sophisticated future brain-machine interfaces.