Non-Imaging Gas Sensor with Reflective Cavity for Fast Equilibration
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Solution Overview
Problem
Current transcutaneous gas sensors face challenges such as slow gas permeation through tissues, requiring small measurement chamber volumes or long equilibration times, and are prone to interference and manufacturing complexities, leading to unreliable and costly devices with frequent calibration needs.
Innovation Solution
A miniaturized sensor design featuring a detector with a single wavelength-sensitive element and non-imaging optical elements, allowing for compact and cost-effective construction, with a measurement volume that enables efficient gas detection and reduced manufacturing tolerances, and a gas collector for faster equilibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the measurement chamber volume is reduced to achieve faster gas equilibration, then the response time is improved, but the optical intensity becomes insufficient for reliable detection
Solution Approach 1:
The patent transitions from a conventional linear optical path to a three-dimensional integrating cavity design. The measurement chamber is configured as a cavity with highly reflective inner surfaces that cause multiple reflections of optical radiation, effectively increasing the interaction path length between light and gas molecules without increasing the physical volume. This dimensional transformation allows sufficient optical absorption in a compact space, resolving the contradiction between small volume (fast equilibration) and sufficient optical intensity (reliable detection).
Solution Approach 2:
The patent introduces highly reflective surfaces as an intermediary element within the measurement chamber. These reflective surfaces act as a mediator that traps and redirects optical radiation multiple times through the gas sample, amplifying the absorption effect without requiring a larger measurement volume. The reflective surfaces enable the compact chamber to achieve the optical path length equivalent of a much larger conventional chamber, thus maintaining both fast response time and sufficient detection sensitivity.
2Measurement precision
If conventional optical sensors with multiple wavelength-sensitive elements are used to achieve accurate gas detection, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent employs a single wavelength-sensitive element that serves multiple functions: it detects the absorption of optical radiation by target gas molecules, monitors reference wavelengths for calibration, and compensates for environmental variations. By designing the system so that one detector element performs what traditionally required multiple separate detectors, the patent significantly reduces device complexity while maintaining measurement precision through intelligent signal processing and the use of multiple wavelengths from a single broadband source.
Solution Approach 2:
The patent extracts and eliminates unnecessary components from conventional optical gas sensors. Instead of using multiple wavelength-sensitive elements, multiple light sources, and complex optical switching mechanisms, the invention retains only the essential single wavelength-sensitive element and broadband light source combination, removing redundant parts while preserving the core measurement functionality. This extraction of essential elements simplifies the device structure without compromising detection accuracy.
3Reliability
If tight manufacturing tolerances are imposed to ensure reliable sensor performance, then the measurement reliability is improved, but the ease of manufacture deteriorates
Solution Approach 1:
The patent changes the critical parameters from dimensional tolerances (alignment precision, surface flatness) to material properties and functional characteristics (reflective surface performance, gas diffusion properties). By designing the measurement chamber as a simple cavity with diffuse reflective surfaces rather than requiring precise optical alignment, the system becomes much less sensitive to manufacturing tolerances. The functional performance depends on achieving sufficient reflectivity and proper gas access, which are easier to control during manufacturing than precise geometric dimensions.
Solution Approach 2:
The patent designs the measurement chamber as a simple, inexpensive component that can be manufactured using conventional techniques without requiring precision optical machining. The cavity structure with diffuse reflective surfaces can be produced through standard molding or machining processes, making the sensor more manufacturable and cost-effective while maintaining reliable performance through the robustness of the design rather than tight tolerances.
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 accurate and reliable detection of gas concentrations within acceptable response times, reducing the need for frequent calibration and improving sensor usability with enhanced manufacturing efficiency and cost-effectiveness.
Implementation Method 1
The wavelength sensitive element is arranged such that radiation in a first wavelength band propagates through the wavelength sensitive element when impinging on the wavelength sensitive element within a first range of incidence angles and is detectable by a first detection surface, while radiation in a second wavelength band propagates through the wavelength sensitive element when impinging on the wavelength sensitive element within a second range of incidence angles and is detectable by a second detection surface
Implementation Method 2
Infrared radiation is emitted by at least one radiation source and guided along at least one path through a measurement volume for receiving the gas to be measured onto at least a first radiation detector
Implementation Method 3
gases diffuse through skin and body tissues and that the gases are detectable on the skin's surface by an appropriate sensor
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.