Non-Invasive Glucose Sensor Thermal Compensation
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Solution Overview
Problem
Existing non-invasive infrared detection systems for measuring glucose concentration in the human body face challenges in achieving high accuracy due to perturbations caused by blackbody emission from system components, which are costly and impractical to mitigate through cryogenic cooling and nitrogen sealing for consumer products.
Innovation Solution
A system that compensates for temperature-related perturbations by using temperature-measuring devices to create a look-up table for calibration, and reduces baffle emissivity through gold-plating and reflectivity enhancement, along with a radiation trap design to minimize stray energy, allowing for accurate glucose concentration measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cryogenic cooling and nitrogen sealing are used to eliminate blackbody emission perturbations, then measurement precision is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent extracts and measures the temperature of individual system elements (baffle, mirrors, filters, detector) separately using thermistors, then removes their blackbody emission effects through calibration and lookup tables. This allows the system to operate at room temperature while compensating for thermal perturbations mathematically, eliminating the need for cryogenic cooling.
Solution Approach 2:
The patent changes the approach from physical temperature control (cryogenic cooling) to parameter compensation (temperature measurement and mathematical correction). By measuring temperatures of all components and using lookup tables to calculate and remove blackbody emission effects, the system achieves high measurement precision without changing the physical temperature of the device components.
2Measurement precision
If baffle emissivity is reduced through gold-plating, then measurement precision is improved, but stray radiation reflection problems arise
Solution Approach 1:
The patent employs a spherical baffle with a polished gold-plated interior surface. The curved spherical geometry is specifically designed to reflect stray radiation away from the detector's field of view. The spherical shape ensures that reflected rays diverge and do not converge back at the detector, effectively eliminating stray radiation interference while maintaining low emissivity.
Solution Approach 2:
The baffle is designed with asymmetric functionality: the spherical interior surface handles stray radiation reflection, while the exterior black coating handles thermal emission. This asymmetric design allows the baffle to simultaneously address both reflection and emission problems without requiring uniform treatment of all surfaces.
3Measurement precision
If temperature measurement and calibration are performed for all system elements, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The system performs self-calibration by automatically measuring its own component temperatures using integrated thermistors and using those measurements to generate lookup tables that compensate for blackbody emission. The system serves its own calibration needs without requiring external reference standards or complex calibration equipment, reducing overall system complexity.
Solution Approach 2:
The patent performs preliminary calibration actions by measuring the blackbody emission characteristics of each component at various temperatures and storing this data in lookup tables before actual glucose measurements are taken. This preliminary characterization allows the system to automatically compensate for thermal effects during normal operation without adding complexity to the 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
The system achieves high accuracy in glucose concentration measurement by effectively accounting for temperature effects and reducing stray radiation, making it feasible for consumer use.
Implementation Method 1
a detector for sensing radiation emitted or remitted from a body, a human body, for example
Implementation Method 2
glucose and other blood constituents have strong and distinguishable absorption spectra in both the middle and far infrared regions
Implementation Method 3
An optical system is provided and aligned to focus IR radiation emitted by the body on a sensitive area of the detector
Implementation Method 4
the blackbody emission of any component of the system (mirrors, filters, field limiters, detector, for example) can cause perturbations in the measurement
Implementation Method 5
enhancing its reflectivity... The baffle design reduces reflection or multiple reflections from reaching the sensitive area of the detector
Data Source
AI summary
A system for non-invasive measurement of a substance, such as glucose, includes a detector configured to sense radiation and an optical subsystem configured to focus the radiation on a sensitive area of the detector. The system includes one or more temperature sensors attached to one or more of a plurality of elements of the optical subsystem and to the detector and two or more temperature sensors configured to measure two or more respective ambient temperatures. The one or more temperature sensors are configured to measure the temperature of the one or more elements of the optical subsystem and the temperature of the detector. A method of measuring a concentration includes detecting an infrared radiation value, measuring the temperature of the detector, one or more components of the optical system, and two or more ambient temperatures, and correlating the temperatures with calibration parameters to correct the detected infrared radiation value.