SWIR Detector Array for Noninvasive Glucose Monitoring
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Solution Overview
Problem
Current noninvasive glucose monitoring methods using near-infrared diffuse-reflectance spectroscopy fail to meet FDA accuracy standards due to measurement errors exceeding ±15 mg/dL, necessitating a more sensitive and accurate approach for blood glucose level detection.
Innovation Solution
Employing a detector array operating in the short-wave infrared band with multiple photosites and a color filter array to enhance signal-to-noise ratio, exclude irregular measurement points, and calibrate intensity to radius dependency, allowing for precise glucose concentration measurements by analyzing light absorption changes at specific wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If near-infrared diffuse-reflectance spectroscopy is used for noninvasive glucose monitoring, then the measurement can be performed noninvasively, but the measurement error exceeds FDA accuracy standards (16-30 mg/dl error)
Solution Approach 1:
The patent changes the wavelength parameter from near-infrared (NIR) to short-wave infrared (SWIR) range. This parameter change enables better glucose detection sensitivity while maintaining noninvasive measurement capability, resolving the contradiction between ease of operation and measurement precision.
Solution Approach 2:
The patent transitions from using a single photosite detector to a detector array with multiple photosites. This dimensional change from 0D (single point) to 2D (array) enables spatial sampling of the diffuse reflectance signal, improving measurement precision through multiple instantaneous measurements and statistical analysis while maintaining noninvasive operation.
2Device complexity
If a single photosite detector is used, then the device complexity is low, but the signal-to-noise ratio is insufficient for accurate glucose measurement
Solution Approach 1:
The patent employs a detector array with multiple photosites arranged in a two-dimensional configuration. This dimensional expansion enables spatial sampling of the optical signal at different positions, providing multiple instantaneous measurements that improve signal-to-noise ratio through statistical averaging while maintaining manageable device complexity.
Solution Approach 2:
The patent combines signals from multiple photosites located at similar distances from the illumination source through averaging. This merging of multiple detection channels improves the signal-to-noise ratio by reducing random measurement variations, achieving more reliable glucose concentration measurements.
3Reliability
If multiple photosites are used for statistical averaging, then the signal-to-noise ratio improves, but the device complexity increases
Solution Approach 1:
The detector array is segmented into multiple photosites with specific spatial arrangements. By dividing the detection function across multiple segmented photosites rather than using a single detector, the system achieves improved signal-to-noise ratio through statistical averaging while managing complexity through systematic segmentation.
Solution Approach 2:
The detector array serves multiple functions simultaneously: it provides spatial sampling of the diffuse reflectance signal, enables statistical averaging for improved signal-to-noise ratio, and allows for exclusion of irregular measurement points through image processing. This multi-functionality justifies the increased device complexity.
4Measurement precision
If SWIR wavelengths are used for glucose measurement, then the measurement accuracy meets FDA standards, but the device complexity increases due to specialized detector requirements
Solution Approach 1:
The patent specifies operation in the short-wave infrared wavelength range (approximately 900-1700 nm) where glucose exhibits strong absorption features. This wavelength parameter change enables accurate glucose measurement while utilizing available SWIR detector technology, balancing measurement precision with device complexity.
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 method provides accurate noninvasive glucose monitoring within FDA-regulated error margins, with the potential for measuring other compounds like cholesterol and hemoglobin, offering improved sensitivity and reliability.
Implementation Method 1
near infrared (NIR) diffuse-reflectance spectroscopy (DRS) where a spectroscopic measurement is taken from a reflection from the from the upper skin layers
Implementation Method 2
Blood absorption in the SWIR range changes significantly with changes in glucose concentration levels
Data Source
AI summary
A device and method for detecting the level of a compound in tissue, the device including: an illumination source operable to emit light from an optical opening into the tissue; a detector array having a plurality of photosites, each operable to detect light of the illumination source travelling through the tissue; wherein different photosites of the detector array are located at different distances from the optical opening; and a processor adapted for determining compound levels in the tissue based on differences in detected illumination levels at distinct wavelengths at different distances from the optical opening.