Non-Imaging CO2 Sensor Layout for Faster Transcutaneous Detection
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Solution Overview
Problem
Current gas sensors for transcutaneous CO2 measurement are prone to drift, require frequent calibration, and have long response times, making them bulky and difficult to use in clinical settings, especially due to challenges in miniaturization and interference from evanescent fields.
Innovation Solution
A miniaturized sensor design using a detector with a common wavelength sensitive element and non-imaging optical elements, allowing for compact construction and reduced manufacturing tolerances, along with a non-imaging optical path and reflective surfaces to enhance measurement accuracy and reduce calibration needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensor uses a measurement chamber for transcutaneous gas detection, then gas measurement capability is achieved, but the response time becomes unacceptably long due to slow gas permeation through skin
Solution Approach 1:
The measurement chamber is divided into multiple smaller chambers arranged in parallel, each with its own optical path. This segmentation reduces the volume of each individual chamber, allowing faster gas equilibration while maintaining overall measurement capability through combined signals from multiple chambers.
Solution Approach 2:
The patent transitions from a single large-volume measurement chamber to multiple small-volume chambers arranged in a two-dimensional array. This dimensional change allows the system to achieve fast response times (comparable to blood gas analysis) while maintaining sufficient measurement sensitivity through the combined optical signals from all chambers.
2Loss of time
If an optical sensor uses a tiny measurement chamber for fast response, then response time is reduced, but optical intensity becomes insufficient for accurate detection
Solution Approach 1:
Multiple optical paths from separate small measurement chambers are merged into a single detection system. The optical signals from all chambers are combined and detected together, accumulating sufficient optical intensity for accurate measurement while each individual chamber maintains fast response characteristics.
Solution Approach 2:
The optical detection system is segmented into multiple independent optical paths, each corresponding to a small measurement chamber. This allows each path to benefit from fast gas equilibration in small volumes while the aggregate signal from all paths provides sufficient optical intensity for detection.
3Volume of moving object
If a sensor system uses an optical fiber with evanescent field for gas detection, then compact design is achieved, but manufacturing precision requirements become extremely high
Solution Approach 1:
The patent extracts the optical fiber evanescent field interaction component and replaces it with a free-space optical path through the measurement chamber. This eliminates the need for precise fiber-to-chamber alignment and evanescent field coupling, significantly reducing manufacturing and assembly precision requirements while maintaining compact sensor dimensions.
4Measurement precision
If a sensor uses single monomodal optical propagation for gas detection, then measurement specificity is improved, but device complexity and manufacturing difficulty increase dramatically
Solution Approach 1:
Instead of using complex monomodal optical propagation control, the patent uses multiple independent optical paths that are simpler to manufacture. Each path provides a measurement signal that is processed and combined, achieving sufficient specificity without the extreme manufacturing tolerances required for true monomodal propagation.
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 sensor provides accurate, rapid CO2 detection with response times under 10 minutes, minimizing calibration requirements and improving usability in clinical settings.
Implementation Method 1
The wavelength sensitive element is substantially transparent for radiation of wavelengths in a first wavelength band when this radiation is incident onto the wavelength sensitive element in a first range of incidence angles
Implementation Method 2
detector for detection of electromagnetic radiation emitted by a source
Implementation Method 3
The concentrations of the detected gas is then typically translated into the arterial partial pressure of the gas using a mathematical relationship
Data Source
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AI summary
A sensor (1) for detection of gas, in particular for detection of CO2, comprises a contact face (2) which is directable towards a measuring site. The sensor (1) comprises at least one radiation source (3), a measurement volume (4) for receiving the gas to be measured, and at least a first detector (5) for detection of radiation transmitted from the source (3) to the first detector (5) through the measurement volume (4). The sensor comprises a path (6) of the radiation between radiation source (3) and first detector (5), wherein the radiation propagates along the path in a non-imaging way.