Brain Function Measurement Probe with Optical Attenuator
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Solution Overview
Problem
The signal-to-noise ratio (S/N ratio) varies significantly depending on the amount of hair at measurement locations when using multichannel functional near-infrared spectroscopy, making it difficult to compare data obtained at different locations.
Innovation Solution
A brain function measurement device and method using three probes with optical attenuators disposed at the vertexes of a regular triangle, where the transmittances are initialized and adjusted to equalize light amounts across channels, ensuring optimal light emission and detection, thereby leveling data to achieve a best S/N ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multichannel functional near-infrared spectroscopy is performed with probes disposed at different measurement locations, then measurement coverage and channel density are improved, but the signal-to-noise ratio varies significantly due to varying hair amounts at different locations
Solution Approach 1:
The patent applies local quality by adjusting the transmittance of optical attenuators individually for each probe based on the specific light amount detected at that measurement location. The control unit sets transmittance values tailored to each probe's local conditions (hair amount, tissue properties), allowing each measurement channel to achieve optimal S/N ratio despite varying local characteristics. This resolves the contradiction by making the system adaptive to local variations rather than applying uniform settings across all measurement locations.
2Measurement precision
If optical attenuators are added to each probe to enable transmittance adjustment, then the ability to equalize light amounts across channels is improved, but device complexity increases
Solution Approach 1:
The patent implements parameter changes by dynamically adjusting the transmittance parameter of optical attenuators in each probe. The control unit modifies the transmittance values based on detected light amounts, enabling flexible adaptation of optical properties without changing the physical structure of the probes. This resolves the contradiction by achieving light amount equalization through parameter adjustment rather than complex structural modifications.
Solution Approach 2:
The optical attenuators serve as intermediary elements between the light sources and detectors in each probe. These intermediaries allow precise control of light transmission, enabling the system to equalize light amounts across different measurement channels. The attenuators mediate the optical signal to compensate for variations in hair amount and tissue properties, resolving the contradiction between measurement precision and device complexity.
3Measurement precision
If transmittance adjustment is performed to equalize light amounts across all channels, then data comparability between different measurement locations is improved, but the number of adjustment steps and processing time increase
Solution Approach 1:
The patent applies preliminary action by performing transmittance adjustment before actual brain function measurement. The control unit first measures light amounts in each channel, calculates appropriate transmittance values, and sets the attenuators accordingly. This preliminary calibration ensures that all channels have equalized light amounts and optimal S/N ratios before the main measurement begins, thereby improving data comparability while minimizing time loss during the actual measurement process.
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
This approach allows for data obtained at different measurement locations to be compared easily by ensuring all channels have a consistent S/N ratio, enhancing the reliability of brain function measurements through functional near-infrared spectroscopy.
Implementation Method 1
three probes, each of the three probes having an optical attenuator provided at a distal end
Implementation Method 2
performing measurement by functional near-infrared spectroscopy
Data Source
AI summary
A device including a measuring unit having probes for emitting or detecting light with optical attenuators at points forming a regular triangle, and a control unit to: set transmittances of the attenuators so that an amount of light from the probes becomes a desired value; identify, among three channels, a first channel having a maximum light amount; perform detection in second and third channels between first and second probes of the first channel and a third probe; adjust transmittance of the attenuator of the first or the second probe of the channel having a smaller light amount so that light amounts in the second and the third channels become equal; adjust transmittance of the attenuator of the third probe so that the light amount of the second or the third channel becomes equal to the light amount of the first channel; and perform measurement with all transmittances after adjustments maintained.