Closely Spaced Brain Sensor Electrodes for High-Resolution EEG
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Solution Overview
Problem
Current non-invasive brain signal monitoring techniques, such as EEG and MEG, face limitations in spatial and temporal resolution, are noisy, and require extensive setup time, making them unsuitable for high-resolution measurements and practical applications like brain-computer interfaces and epilepsy research.
Innovation Solution
A sensor assembly with closely spaced electrodes arranged in various patterns, including hexagonal and circular configurations, measures electric field and potential activity, enabling higher order derivatives like the Laplacian, and uses a microcontroller for signal processing to achieve improved signal-to-noise ratio through weighted averaging and active amplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If EEG sensors are miniaturized to increase spatial resolution, then electrode separation can be reduced, but signal quality degrades due to noise and crosstalk
Solution Approach 1:
The patent introduces an intermediary reference electrode that is electrically connected to multiple sensing electrodes through resistors. This reference electrode acts as a mediator to provide a common reference potential, enabling the system to compute local voltage gradients and eliminate common-mode noise. The intermediary structure allows miniaturized electrodes to maintain signal quality by referencing measurements to a shared potential rather than using traditional global references.
Solution Approach 2:
The patent implements local quality by using multiple reference electrodes distributed across the sensor array, with each reference electrode serving a local group of sensing electrodes. This local referencing approach allows the system to adapt to spatial variations in noise and potential distribution, improving measurement precision in different regions of the scalp while maintaining miniaturized electrode dimensions.
2Manufacturing precision
If a large number of sensors are used to improve spatial resolution, then measurement density increases, but setup time and complexity increase
Solution Approach 1:
The patent applies universality by designing a modular sensor assembly where a single integrated circuit board can support multiple sensing electrodes and reference electrodes in various configurations. The same hardware platform can be used for different electrode arrangements (e.g., 19-channel, 32-channel, or 64-channel systems), reducing the need for separate setup procedures for different sensor densities and thereby reducing overall setup time.
Solution Approach 2:
The patent segments the sensor system into modular units that can be independently configured and assembled. Each sensor assembly can be pre-configured with specific electrode patterns before use, allowing rapid deployment without complex on-site assembly. This segmentation enables the system to achieve high spatial resolution while maintaining efficient setup procedures.
3Reliability
If traditional EEG reference and grounding electrodes are used, then global reference is established, but local measurements are contaminated by global brain activity
Solution Approach 1:
The patent resolves this contradiction by implementing local quality through distributed reference electrodes that are positioned close to the sensing electrodes. Each local reference provides a reference potential that is specific to its region, allowing the system to measure local voltage gradients without contamination from distant global brain activity. This local referencing approach maintains reference stability while improving local measurement accuracy.
Solution Approach 2:
The patent uses intermediary reference electrodes that are electrically connected to multiple sensing electrodes through resistors. These intermediary references act as local common-mode rejection points, enabling the system to eliminate global noise while preserving local signal integrity. The intermediary structure provides a stable reference that is localized rather than global, resolving the conflict between reference stability and local measurement accuracy.
4Loss of time
If liquid electrolytes are used to reduce setup time, then electrode application is simplified, but conductive bridges form between electrodes increasing crosstalk
Solution Approach 1:
The patent employs disposable conductive gels or pastes that are applied locally at each electrode site and then discarded after a single use. These short-living conductive elements provide sufficient conductivity during the measurement session without persisting long enough to create conductive bridges between electrodes. This approach maintains signal isolation while keeping setup time short, as the conductive elements are pre-applied or quickly applied and then discarded.
Solution Approach 2:
The patent extracts the harmful conductive bridge formation by using localized conductive elements that are physically separated at each electrode site rather than using a continuous liquid electrolyte medium. By taking out the continuous conductive path and replacing it with discrete localized conductors, the system maintains electrode-to-scalp conductivity while preventing inter-electrode crosstalk.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system provides higher spatial resolution and improved signal-to-noise ratio, allowing for more accurate brain activity imaging and real-time monitoring, suitable for diverse neurological applications including epilepsy diagnosis and brain-computer interfaces.
Implementation Method 1
The electric field vector is given by the negative gradient of the electric potential (measured by EEG) and can provide additional information.
Implementation Method 2
The human brain emits electric and magnetic signals that can be detected outside of the head, provided instruments with sufficient sensitivity are available.
Data Source
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Figure 5A~5B
AI summary
A sensor system and process for measuring electromagnetic activity of a brain are provided. The system and process employ a sensor assembly having a plurality of electrodes arranged in a closely spaced arrangement and a processor to determine a weighted average of the signals indicative of an electric field generated by electromagnetic activity of the brain. The system provides a medical body area network of a subject including one or more of the sensor assemblies and one or more additional sensors, which may be within a smartphone or other wearable device.