Transcutaneous CO2 Sensor with Removable Protective Layer
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Solution Overview
Problem
Current non-invasive CO2 monitoring technologies for patients with chronic respiratory failure are unreliable due to air leaks, moisture, and skin variability, requiring frequent calibration and skilled personnel, and are not suitable for home use.
Innovation Solution
An optical sensor unit with a gas-permeable layer and sensing layer protected by a removable protective layer, allowing calibration during manufacturing and eliminating the need for pre-use calibration, combined with a contact medium to maintain osmolarity and prevent deterioration, enabling accurate and user-friendly transcutaneous CO2 monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transcutaneous CO2 monitoring is used, then non-invasive CO2 measurement is achieved, but the sensor requires frequent calibration and skilled personnel due to drift and skin variability
Solution Approach 1:
The sensor is pre-calibrated during manufacturing with reference gas mixtures, and the calibration data is stored in memory. This preliminary calibration action eliminates the need for frequent on-site calibration by the user, resolving the contradiction between measurement reliability and ease of operation.
Solution Approach 2:
The sensor performs self-diagnosis and self-calibration using stored reference data. The microcontroller automatically compensates for drift and environmental variations without requiring skilled personnel intervention, making the device easy to use while maintaining reliability.
2Reliability
If capnography is used for CO2 monitoring, then trend monitoring is achieved, but the method is unreliable due to air leaks and moisture in tubes
Solution Approach 1:
A gas-permeable membrane acts as an intermediary between the patient's skin and the sensor. This membrane selectively allows CO2 to pass through while blocking moisture and other interfering substances, eliminating the harmful effects of air leaks and moisture that plague capnography systems.
Solution Approach 2:
The patent replaces the mechanical tube-based capnography system with an optical sensor that detects CO2 through the skin. This substitution eliminates the physical tubes that are susceptible to air leaks and moisture contamination, thereby improving reliability.
3Reliability
If electrochemical pH sensor is used for transcutaneous CO2 monitoring, then CO2 measurement is achieved, but the sensor membrane and electrolyte solution require replacement every 2 weeks
Solution Approach 1:
The patent employs a disposable sensor design where the entire sensor unit including the membrane and electrolyte is replaced periodically. This approach is more cost-effective than maintaining and recalibrating complex reusable sensors, and the short lifespan ensures consistent performance without degradation.
Solution Approach 2:
The sensor is designed as a segmented modular unit that can be easily replaced. The gas-permeable membrane, electrolyte solution, and sensing elements are integrated into a replaceable cartridge that attaches to a reusable housing, allowing periodic replacement of consumable parts while retaining expensive electronics.
4Ease of operation
If pulse oximetry is used for oxygen monitoring, then easy home use is achieved, but it only measures oxygen saturation and not CO2 levels
Solution Approach 1:
The sensor unit is designed to measure multiple parameters including CO2, O2, and pH simultaneously through the same skin interface. This multi-functional capability extends the versatility of simple transcutaneous sensors beyond single-parameter pulse oximetry, allowing comprehensive respiratory monitoring at home.
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 solution provides a reliable, easy-to-use, and cost-effective method for monitoring CO2 levels without the need for frequent calibration or skilled personnel, suitable for home use, enhancing patient monitoring and ventilation management.
Implementation Method 1
a gas-permeable layer adjacent to one side of the at least one sensing layer and adapted to pass gas which concentration is to be measured through the gas-permeable layer towards the sensing layer
Implementation Method 2
the optical sensor unit is adapted to measure an optical response of the at least one sensing layer which optical response depends on the concentration of the gas
Data Source
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AI summary
An optical sensor unit (10) for measuring a concentration of a gas is provided, comprising at least one sensing layer (122) adapted to be irradiated with a predetermined radiation; at least one gas-permeable layer (121) adjacent to one side of the at least one sensing layer (122) and adapted to pass gas which concentration is to be measured through the gas-permeable layer (121) towards the sensing layer (122); a removable protective layer (150) covering at least the gas-permeable layer (121) and adapted to be removed before use of the optical sensor unit (10), wherein the optical sensor unit (10) is adapted to measure an optical response of the at least one sensing layer (122), which optical response depends on the concentration of the gas.