Integrated Gas Sensor With Cavity-Based IR Filtering for Compact Detection
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Solution Overview
Problem
There is a need for gas sensors that can be produced cost-effectively while maintaining or improving reliability and accuracy, and that have reduced fabrication requirements and adequate sensitivity for target gas detection.
Innovation Solution
An integrated gas sensor design utilizing a substrate with a cavity for optical interaction, a thermal emitter, wavelength selective structures, and an IR detector, fabricated using semiconductor technology, which allows for a compact, mass-producible system with high selectivity and fast response times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional optical sensors are assembled from discrete sub-components, then the sensor can be manufactured with standard components, but the sensor becomes bulky and complex
Solution Approach 1:
The patent integrates the light source, wavelength selective filter, detector, and sample chamber into a single monolithic semiconductor substrate. This merging of discrete components into one integrated device reduces the overall sensor complexity and size while maintaining manufacturing reliability through standard semiconductor fabrication processes
2Reliability
If traditional optical sensors are assembled from discrete sub-components, then the sensor can be manufactured with standard components, but the sensor becomes bulky
Solution Approach 1:
The patent integrates the light source, wavelength selective filter, detector, and sample chamber into a single monolithic semiconductor substrate. This merging of discrete components into one integrated device reduces the overall sensor complexity and size while maintaining manufacturing reliability through standard semiconductor fabrication processes
Solution Approach 2:
The patent utilizes three-dimensional integration within the semiconductor substrate, stacking functional layers vertically to achieve compact form factor. The waveguide structure guides light through multiple layers in the vertical dimension, enabling high functionality in a small footprint
3Productivity
If the sensor is integrated at chip-scale, then the sensor becomes compact and mass-producible, but the fabrication requirements become more stringent
Solution Approach 1:
The patent replaces mechanical assembly of discrete components with semiconductor fabrication processes. Standard CMOS-compatible techniques such as photolithography, thin-film deposition, and wafer bonding are used to create the integrated sensor, enabling mass production with controlled precision through established semiconductor manufacturing infrastructure
4Speed
If the light source and detector are thermally coupled to the gas sample, then the sensor responds quickly to gas changes, but the sensor reliability decreases due to contamination and drift
Solution Approach 1:
The patent physically separates the light source and detector from the gas sample chamber using a waveguide structure. The waveguide acts as a thermal and chemical barrier, allowing optical energy to pass while blocking mass transport. This segmentation protects the sensitive optical components from gas contamination while maintaining quick response through efficient light-gas interaction in the sample chamber
Solution Approach 2:
The waveguide structure serves as an intermediary between the gas sample chamber and the light source/detector. It transmits optical energy from the light source through the gas sample to the detector while preventing direct thermal and chemical contact between the gas and the sensitive optical components, thus ensuring both fast response and long-term stability
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 integrated gas sensor provides high selectivity, accuracy, and fast response times, enabling reliable monitoring of air quality and potential integration into consumer devices and large sensor networks, with a compact design achievable through chip-scale production.
Implementation Method 1
a thermal emitter (130) arranged for emitting a broadband or incoherent IR radiation R0
Implementation Method 2
a wavelength selective structure (140) arranged for filtering the broadband or incoherent IR radiation R0 and for providing a filtered IR radiation R having a center wavelength l0
Implementation Method 3
for sensing an amount or a concentration of a target gas component in an environmental gas or environmental gas mixture
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
According to an embodiment, a gas sensor (100) comprises: a substrate (110) having a cavity (120) for providing an optical interaction path (120-1) for an interaction of a filtered IR (IR = infrared) radiation having a center wavelength λ0 with a target gas in the cavity (120), wherein the cavity (120) is accessible for an environmental gas comprising the target gas component; a thermal emitter (130) arranged for emitting a broadband IR radiation, wherein the thermal emitter is optically coupled to the cavity (120); a wavelength selective structure (140) arranged for filtering the broadband IR radiation emitted by the thermal emitter and for providing the filtered IR radiation having the center wavelength λ0 in the cavity (120), wherein the wavelength selective element is optically coupled between the thermal emitter and the cavity (120), or wherein the wavelength selective element is formed as a bound structure of the cavity (120); an IR detector (150) arranged to provide a detector output signal based on a signal strength of the filtered IR radiation having traversed the optical interaction path in the cavity (120) and being received by the IR detector.