Noninvasive Blood Glucose Sensor Calibration via Invasive Feedback

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Solution Overview

Problem

Conventional pulse oximetry systems face challenges in accurately measuring blood oxygen saturation and pulse rate during patient movement, low perfusion, intense ambient light, and electrosurgical instrument interference.

Innovation Solution

The integration of advanced pulse oximetry systems that include low noise optical sensors and read-through motion capabilities, combined with noninvasive blood glucose measurement systems that calibrate optical sensor measurements with intermittent invasive test strip measurements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional pulse oximetry is used to measure blood oxygen saturation, then the measurement can be obtained continuously, but the measurement accuracy deteriorates during patient motion, low perfusion, intense ambient light, and electrosurgical instrument interference

Engineering Contradiction:

Improvemeasurement accuracyVSAvoidpatient motion, low perfusion, ambient light interference, electrosurgical interference

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system changes multiple parameters simultaneously: uses multiple wavelengths (red, infrared, and additional wavelengths) to differentiate blood components, employs advanced signal processing algorithms to filter motion artifacts, and adjusts measurement parameters dynamically to compensate for low perfusion and ambient light conditions

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The pulse oximetry system measures multiple parameters simultaneously (oxygen saturation, pulse rate, perfusion index) and can differentiate between arterial and venous blood signals, making it universally applicable across various clinical conditions including motion, low perfusion, and light interference

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Measurement precision

If frequent invasive blood draws are performed to measure blood glucose levels, then measurement accuracy is high, but patient discomfort and infection risk increase

Engineering Contradiction:

Improveblood glucose measurement accuracyVSAvoidpatient discomfort, infection risk, frequent blood draws

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The system replaces the mechanical invasive blood draw method with an optical measurement system that uses light absorption and scattering properties of blood to determine glucose levels noninvasively, eliminating needles and skin punctures

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system uses optical sensors and light as an intermediary to indirectly measure blood glucose levels through tissue penetration and absorption, rather than directly extracting blood samples

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If noninvasive optical sensor measurements are used for blood glucose, then patient comfort improves, but measurement accuracy deteriorates without calibration

Engineering Contradiction:

Improvepatient comfortVSAvoidblood glucose measurement accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The system uses intermittent invasive test strip measurements as feedback to calibrate and adjust the noninvasive optical sensor readings, ensuring continuous accuracy while maintaining patient comfort during routine monitoring

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs preliminary calibration using invasive measurements before transitioning to noninvasive monitoring, establishing an accurate baseline that enables subsequent noninvasive measurements to maintain precision

Inventive Principle:

Principle #10Preliminary action

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

These systems provide accurate and reliable measurements of blood oxygen saturation, pulse rate, and blood glucose levels, even under challenging conditions, reducing errors and the need for frequent invasive blood draws.

Implementation Method 1

The detector generates a photoplethysmograph signal responsive to the emitted light after attenuation by pulsatile blood flow within the tissue site

Methodology Applied

Scientific EffectLight attenuation: Absorption (EM radiation)

Implementation Method 2

The detector generates a photoplethysmograph signal responsive to the emitted light after attenuation

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS20250127435A1Blood glucose sensing system

Publication Date: 2025.04.24 MASIMO CORP

AI summary

A blood glucose sensing system includes a plurality of physiological sensors. The system can estimate blood glucose based on discrete invasive blood glucose estimates from a blood sample, discrete noninvasive blood glucose estimates derived from optical sensors, and continuously-calculated blood glucose estimates derived from a nonlinear state-space model of glucose and insulin reactions within a human body. The state-space model has user-entered values corresponding to their insulin and meal intake. The user's blood glucose is estimated from a combination of the discrete invasive blood glucose estimates, the discrete noninvasive blood glucose estimates and the continuously-calculated blood glucose estimate.