Chemo-Optical Sensor Binding Layer for Volatile Acid Cross-Sensitivity
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Solution Overview
Problem
Current transcutaneous CO2 sensors are prone to non-reversible drift due to cross-sensitivity with volatile acids and bases, which affects their accuracy in measuring CO2 concentrations, especially in environments where these substances are present.
Innovation Solution
Incorporating a volatile acid and/or base binding layer in the gas-pathway from the skin to the sensing layer, which binds or converts unwanted volatile acids and bases into non-volatile molecules, reducing their impact on the sensor's response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a gas-permeable sensing layer is used for transcutaneous CO2 measurement, then the sensor can measure CO2 concentration through the skin, but the sensor becomes cross-sensitive to volatile acids and bases causing non-reversible drift
Solution Approach 1:
A volatile acid and/or base binding layer is introduced as an intermediary component between the skin and the sensing layer. This binding layer selectively binds volatile acids and bases while allowing CO2 to pass through, thereby protecting the sensing layer from cross-sensitivity without interfering with the primary measurement function.
Solution Approach 2:
The sensor structure is segmented into distinct functional layers: a volatile acid/base binding layer and a gas-permeable sensing layer. This segmentation allows each layer to perform its specific function independently - the binding layer handles interference substances while the sensing layer focuses on CO2 detection.
2Reliability
If a volatile acid and/or base binding layer is added to the sensor structure, then cross-sensitivity to volatile acids and bases is reduced, but the device complexity increases
Solution Approach 1:
The volatile acid/base binding layer is implemented as a thin film structure that can be integrated into the existing sensor architecture. This thin-film approach provides the necessary protective function while minimizing the increase in device complexity and maintaining a compact form factor.
Solution Approach 2:
The binding layer is constructed using composite materials that combine selective binding properties for volatile acids and bases with gas permeability for CO2. This composite material approach allows a single layer to perform multiple functions, reducing the need for additional components.
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
This approach significantly reduces the non-reversible cross-sensitivity, maintaining the sensor's accuracy and stability, even in environments with volatile acids and bases, allowing for reliable transcutaneous CO2 monitoring.
Implementation Method 1
Incorporating a volatile acid and/or base binding layer in the gas-pathway from the skin to the sensing layer, which binds or converts unwanted volatile acids and bases into non-volatile molecules
Implementation Method 2
at least a first gas-permeable layer adjacent to one side of the at least one sensing layer, adapted to pass gas whose concentration is to be measured through the gas-permeable layer towards the sensing layer
Implementation Method 3
wherein said chemo-optical sensor unit is adapted to measure an optical response of the at least one sensing layer, whose optical response depends on the concentration of the gas
Data Source
AI summary
The present invention relates to a chemo-optical sensor unit for transcutaneous measurement of a concentration of a gas, comprising: at least one gas-permeable sensing layer adapted to be irradiated with a predetermined radiation; and at least a first gas-permeable layer adjacent to one side of the at least one sensing layer, adapted to pass gas whose concentration is to be measured through the gas-permeable layer towards the sensing layer; at least one volatile acid and/or base binding layer in the gas-pathway from the skin to the sensing layer; adapted to pass gas whose concentration is to be measured through the volatile acid and/or base binding layer towards the sensing layer; wherein said chemo-optical sensor unit is adapted to operate with a contact medium between the chemo-optical sensor unit and the skin and wherein the chemo-optical sensor unit is adapted to measure an optical response of the at least one sensing layer, whose optical response depends on the concentration of the gas. The present invention also relates to a system for patient monitoring and/or ventilation of a patient comprising such a chemo-optical sensor.