Implantable Optical Sensor for Calibrated Tissue Oxygen Saturation Monitoring
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Ambulatory monitoring of blood or tissue oxygen saturation in implantable medical devices is limited to short periods and is affected by body motion, optical path length, and sensor location, leading to unreliable uncalibrated measurements, necessitating a sensor capable of monitoring calibrated tissue oxygen saturation and total hemoglobin volume fraction for chronic ambulatory patient monitoring.
Innovation Solution
An implantable or wearable optical sensor with a light emitting and detecting portion, sealed in a hermetically enclosed housing, using LEDs or other light sources to emit light at specific wavelengths, and a photodetector to measure tissue oxygen saturation and total hemoglobin volume fraction, with integrated circuitry for computing and calibrating these measurements, reducing size and power requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If uncalibrated oxygen saturation measurements are used for ambulatory monitoring, then the monitoring period can be extended, but the measurement reliability deteriorates due to body motion, optical path length variations, and sensor location changes
Solution Approach 1:
The patent implements feedback by continuously measuring multiple optical parameters (absorbance at multiple wavelengths, pulse rate, pleth variability index) and using these measurements to dynamically calculate and adjust oxygen saturation values. The system processes incoming optical signals in real-time, comparing them against reference values and adjusting measurements to compensate for motion artifacts and optical path length variations, thereby maintaining measurement reliability over extended monitoring periods
Solution Approach 2:
The patent changes multiple parameters simultaneously: it measures absorbance at multiple wavelengths (not just single wavelength), calculates derived parameters (pleth variability index, mean pulse rate), and uses these changing parameters to compensate for variations in optical path length and sensor position. By monitoring changes in these parameters over time rather than relying on absolute values, the system maintains reliability during ambulatory conditions
2Measurement precision
If external non-invasive fiber optic devices are used for tissue oxygen saturation monitoring, then measurement accuracy is improved, but device size and power requirements increase
Solution Approach 1:
The patent extracts only the essential functional components needed for optical measurement (light source, photodetector, signal processing circuitry) and removes unnecessary bulk components. The device uses miniaturized LEDs and integrated circuits to perform complex spectral analysis, extracting the core measurement capability while eliminating excess size and power consumption associated with external fiber optic systems
Solution Approach 2:
The patent replaces mechanical fiber optic coupling systems with integrated solid-state optoelectronics. Instead of using external fiber optic cables and complex alignment mechanisms, the invention integrates light-emitting diodes and photodetectors in close proximity, using optical paths through tissue without requiring mechanical fiber coupling. This substitution dramatically reduces device size and power requirements while maintaining measurement precision
3Measurement precision
If multiple wavelengths are used for measuring oxygen saturation and hemoglobin concentration, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple measurement functions into a single integrated sensor head. Multiple LEDs emitting at different wavelengths are combined in one housing, along with multiple photodetectors and signal processing circuitry. The device simultaneously measures absorbance at multiple wavelengths, calculates oxygen saturation, hemoglobin concentration, pulse rate, and pleth variability index using a unified processing algorithm, thereby achieving high measurement precision without proportionally increasing device complexity
Solution Approach 2:
The patent implements multi-functionality by designing a single optical sensor that performs multiple measurements: oxygen saturation at multiple wavelengths, total hemoglobin concentration, pulse rate, and pleth variability index. The same optical path and photodetectors used for oxygen saturation measurement also provide data for hemoglobin concentration and pulse rate calculations. This universal approach allows the device to achieve comprehensive physiological monitoring with a single sensor structure, avoiding the need for separate specialized sensors for each parameter
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 reliable, long-term monitoring of tissue oxygen saturation and total hemoglobin volume fraction, providing accurate and calibrated data independent of measurement volume and sensor position, enhancing patient monitoring capabilities.
Implementation Method 1
using LEDs or other light sources to emit light at specific wavelengths
Implementation Method 2
a photodetector to measure tissue oxygen saturation and total hemoglobin volume fraction
Implementation Method 3
monitoring tissue oxygen saturation based on the absorbance of near-infrared light by hemoglobin and myoglobin
Data Source
AI summary
A method and medical device for detecting signals that detects emitted light scattered by a volume of tissue delivered along a first pathway at a plurality of wavelengths to generate corresponding first detected light intensity output signals, detects emitted light scattered by the volume of tissue delivered along a second pathway different from the first pathway at a plurality of wavelengths to generate corresponding second detected light intensity output signals, determines whether a difference between the emitted light detected along the first pathway and the emitted light detected along the second pathway is greater than a predetermined threshold, and alters sensing by the device in response to the determining whether a difference is greater than the predetermined threshold.