Gas Sensor Device Using Gaseous Optical Filter
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Solution Overview
Problem
Existing gas sensors, such as NDIR and GFC spectrometers, face challenges with high production costs, large size, and performance degradation due to the use of multiple thin layers of dielectric material filters and sensitivity to the angle of incidence of electromagnetic radiation.
Innovation Solution
A gas sensor device comprising a semiconductor substrate with a cap that defines three cavities, where the second cavity serves as a gaseous optical filter filled with the gas of interest, providing a compact and cost-effective solution that minimizes the impact of optical source fluctuations and angle of incidence variations by using optically transmissive apertures and reflective surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple thin layers of dielectric material are used to create optical bandpass filters, then filtering performance is improved, but manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent extracts the filtering function from complex solid dielectric layers and transfers it to a simple gaseous medium. The target gas itself is used as the optical filter in the second cavity, eliminating the need for multiple thin dielectric layers while maintaining filtering performance.
Solution Approach 2:
The invention replaces expensive, complex dielectric filter layers with a simple, inexpensive gaseous filter. The gas in the second cavity serves as a disposable, easily replaceable filtering medium that can be filled during manufacturing without requiring precise layer deposition.
2Measurement precision
If interference filters with multiple thin layers are used, then optical filtering is achieved, but production cost increases
Solution Approach 1:
The filtering function is extracted from expensive dielectric materials and implemented using the target gas itself. This eliminates material costs and complex manufacturing processes while achieving the same optical filtering effect through the gas's natural absorption characteristics.
Solution Approach 2:
The invention changes the physical state of the filter from solid (dielectric layers) to gas. This parameter change simplifies manufacturing and reduces cost while maintaining the filtering function, as the gas can be easily introduced into the sealed second cavity during the manufacturing process.
3Adaptability or versatility
If NDIR sensor design is used, then gas measurement capability is provided, but device size becomes large
Solution Approach 1:
The patent implements a nested cavity structure where the second cavity (containing the gaseous filter) is positioned between the first and third cavities. This nested arrangement allows compact integration of multiple functional zones within a small overall footprint, reducing device size while maintaining measurement capability.
Solution Approach 2:
The invention merges the filtering function with the measurement chamber by using the target gas itself as the filter medium. This eliminates the need for separate filter components and reduces the overall device volume while preserving gas measurement functionality.
4Measurement precision
If GFC spectrometer with rotating filter wheel is used, then spectral analysis is achieved, but device complexity and size increase
Solution Approach 1:
The patent extracts the filtering function from a complex rotating filter wheel mechanism and implements it using a static gaseous medium in a sealed cavity. This eliminates mechanical moving parts while achieving spectral filtering through the gas's absorption characteristics.
Solution Approach 2:
The invention replaces the mechanical rotating filter wheel system with a static gaseous filter. This substitution eliminates complex mechanical components, reducing device complexity and size while maintaining spectral analysis capability through optical absorption by the target gas.
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 consistent measurement results over time, reduces noise and long-term drift, and allows for low-cost mass manufacturing, resulting in a compact and efficient gas sensor device.
Implementation Method 1
the second cavity is configured as a gaseous optical filter for the third cavity, and comprises a volume of the gas of interest sealingly disposed in the second cavity
Implementation Method 2
an optical source and a measurement sensor, the internal wall being at least in part light transmissive
Data Source
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AI summary
A gas sensor device (100) is configured to measure a predetermined gas of interest and comprises an enclosure (101) comprising a semiconductor substrate (102) and defining a first cavity (124), an optically transmissive second closed cavity (126) and a third cavity (128). The second cavity (126) is interposed between the first and third cavities (124, 128). The first cavity (124) comprises an inlet port (130) for receiving a gas under test, an outlet port (132) for venting the gas under test. The first cavity (124) also comprises an optical source (112) and a measurement sensor (114). The second cavity (126) is configured as a gaseous filter comprising a volume of the gas of interest sealingly disposed in the second cavity (126), and the third cavity (128) comprises a reference measurement sensor (116) disposed therein.