Brain Function Measurement Device with Optical Attenuator Calibration
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Solution Overview
Problem
Existing brain function measurement devices using functional near-infrared spectroscopy face challenges in maintaining consistent signal-to-noise ratios due to variations in optical attenuation caused by hair and adhesion, requiring precise calibration of optical attenuators.
Innovation Solution
A brain function measurement device and method that adjusts the light amounts between light irradiation and detection probes using optical attenuators to level observed light amounts across channels, eliminating the need for calibration by selecting probes with maximum effective incident light and detection efficiency and performing adjacent channel leveling operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical attenuators are introduced to level noise variance across channels, then measurement precision is improved, but device complexity increases due to the need for calibration of all optical attenuators
Solution Approach 1:
The patent extracts the calibration operation from the device setup process by using a calibration value stored in memory that was pre-obtained during manufacturing. This eliminates the need for on-site calibration of optical attenuators, reducing device complexity while maintaining measurement precision through the use of pre-determined calibration parameters.
Solution Approach 2:
The calibration values for optical attenuators are determined in advance during manufacturing and stored in memory. This preliminary action allows the device to be used immediately without requiring calibration operations at the measurement site, thereby reducing device complexity and setup time while ensuring measurement precision.
2Measurement precision
If calibration operations are performed for all optical attenuators, then measurement precision is improved, but loss of time increases due to the lengthy calibration process
Solution Approach 1:
Calibration values are determined during manufacturing and stored in memory before the device is deployed. This preliminary calibration action eliminates the need for time-consuming calibration operations at the measurement site, significantly reducing loss of time while maintaining measurement precision through the use of pre-determined optimal parameters.
Solution Approach 2:
The patent uses a calibration value that represents the optimal attenuation setting, copying this pre-determined value into memory for reuse. This allows the device to replicate the calibrated state without repeating the calibration process, thereby eliminating time loss while maintaining precision.
3Measurement precision
If optical attenuators are used to equalize light amounts across channels, then measurement precision is improved, but ease of operation deteriorates due to the need for precise attenuation control
Solution Approach 1:
The control unit automatically controls the optical attenuators based on the calibration value stored in memory, eliminating the need for manual adjustment. This self-service operation maintains measurement precision through accurate attenuation control while significantly improving ease of operation, as users simply need to initiate the measurement process without dealing with complex manual adjustments.
Solution Approach 2:
The control unit uses the calibration value to automatically adjust optical attenuators, creating a feedback-controlled system that maintains optimal light amounts across channels. This automated feedback mechanism ensures measurement precision while improving ease of operation, as the system self-regulates without requiring user intervention.
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 noise leveling across channels without calibrating optical attenuators, simplifying device adjustment and maintenance, and enabling statistical comparison of data across different dates and subjects while maintaining a high signal-to-noise ratio within safe light irradiation limits.
Implementation Method 1
functional near-infrared spectroscopy (fNIRS) has been known. Measurement using fNIRS is performed with probes attached to the scalp
Implementation Method 2
introducing optical attenuators between the respective light sources or detectors and the living body, and controlling the optical transmittance of the optical attenuators
Data Source
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AI summary
The present invention addresses the problem of providing a brain function measurement device and a brain function measurement method with which it is possible to eliminate or minimize the need for a calibration operation. The problem is solved by a brain function measurement device including: a first light irradiation probe S1 which irradiates the brain of a subject with light; a first light detection probe D1 which is disposed adjacent to the first light irradiation probe S1 and detects light reflected from the brain among the light irradiated from the first light irradiation probe S1; a second light irradiation probe S2 which is disposed adjacent to the first light detection probe D1 and irradiates the brain of the subject with light; a second light detection probe D2 which is disposed adjacent to the second light irradiation probe S2 and detects light reflected by the brain among the light irradiated from the second light irradiation probe S2; and a control unit 3 which adjusts the light amount irradiated by the second light irradiation probe S2 so that the light amount measured with respect to a channel between the first light detection probe D1 and the second light irradiation probe S2 becomes an observation value observed with respect to a channel between the first light irradiation probe S1 and the first light detection probe D1, and which adjusts the light amount detected by the second light detection probe D2 so that the light amount measured with respect to a channel between the second light irradiation probe S2 and the second light detection probe D2 becomes the observation value.