Implanted Optical Sensor Correcting Tissue Scattering for Glucose Monitoring
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Solution Overview
Problem
Conventional methods for monitoring glucose levels in individuals with diabetes are invasive, inconvenient, and prone to inaccuracies due to optical scattering and absorption by the skin, making continuous and automatic monitoring challenging.
Innovation Solution
A method and device that corrects analyte-dependent optical signals from an implanted sensor by using multiple light sources and detectors to measure and calculate corrected signal values, accounting for diffuse reflectance and autofluorescence, allowing for accurate and consistent glucose monitoring without significantly restricting patient movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If conventional optical monitoring methods are used to detect analyte levels through the skin, then continuous monitoring is enabled, but measurement precision deteriorates due to optical scattering and absorption by skin tissue
Solution Approach 1:
The patent introduces an implanted sensor as an intermediary device that directly contacts the analyte in interstitial fluid, eliminating the need for light to penetrate through scattering skin tissue. The sensor contains fluorophores that emit light signals proportional to analyte concentration, which are then detected by external optics through the skin without requiring the excitation light to traverse the same scattering path, thus resolving the contradiction between continuous monitoring and measurement precision
Solution Approach 2:
The patent replaces the mechanical/chemical test strip method with an optical detection system using implanted fluorophore-containing sensors. This substitution enables continuous automatic monitoring while the implanted nature of the sensor ensures that optical measurements are taken from within the tissue environment, minimizing scattering effects and improving measurement precision
2Ease of operation
If implanted sensors are used for continuous monitoring, then convenience is improved, but measurement precision deteriorates due to dynamic skin changes causing optical scattering and absorption
Solution Approach 1:
The implanted sensor acts as an intermediary that is physically embedded in the tissue, allowing optical detection to occur from within the tissue environment rather than through the skin surface. This eliminates the problem of dynamic skin changes (blood level, hydration) affecting the optical path, as the fluorophores are surrounded by interstitial fluid rather than being viewed through varying skin conditions
Solution Approach 2:
The patent transitions from surface-level optical detection through the skin to subsurface detection by implanting the sensor within the tissue matrix. This dimensional change places the light source and detector in a more stable optical environment, reducing the impact of skin scattering and absorption variations on measurement precision
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
Enables accurate and consistent monitoring of glucose levels, reducing the risk of hyperglycemic or hypoglycemic episodes by providing continuous and automatic alerts, improving patient safety and convenience.
Implementation Method 1
The implant is capable of emitting, in response to excitation light within an excitation wavelength range, the analyte-dependent optical signal within an emission wavelength range
Implementation Method 2
The skin is highly scattering, and the scattering may dominate the optical propagation. Scatter is caused by index of refraction changes in the tissue
Implementation Method 3
The main absorption is caused by blood, melanin, water, and other components
Data Source
AI summary
An optical device is used to monitor an implant embedded in the tissue of a mammal (e.g., under the skin). The implant receives excitation light from the optical device and emits light that is detected by the optical device, including an analyte-dependent optical signal. Scatter and absorption properties of tissue change over time due to changes in hydration, blood perfusion and oxygenation. The optical device has an arrangement of light sources, filters and detectors to transmit excitation light within excitation wavelength ranges and to measure emitted light within detection wavelengths. Changes in scattering and absorption of light in the tissue, such as diffuse reflectance, are monitored. The light sources, filters and detectors may also be used to monitor autofluorescence in the tissue to correct autofluorescence background.