Integrated IR Light Source and Sensor for Gas Detection
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Solution Overview
Problem
Existing nondispersive infrared (NDIR) gas sensors require two photodetectors and complex reflector arrangements, leading to errors due to variations in the light source's emission spectrum with aging, which complicates the estimation of gas concentrations.
Innovation Solution
A compact device integrating a light source and an infrared-light sensor within a single component, where the light source emits infrared light through a substrate and cover, and the sensor detects the intensity, eliminating the need for separate reference and measuring channels by using a shared optical filter for both spectral bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two separate photodetectors and reflector arrangements are used for reference and measurement channels, then gas concentration measurement capability is improved, but device complexity increases
Solution Approach 1:
The patent combines the reference photodetector and measurement photodetector into a single integrated photodetector unit. The reference channel and measurement channel are merged into one device, eliminating the need for separate photodetectors and reflector arrangements. This reduces device complexity while maintaining the capability to perform both reference measurements and gas concentration measurements through sequential or simultaneous operation of the integrated photodetector.
2Measurement precision
If separate reference and measurement channels with different spectral bands are used, then gas species detection capability is improved, but error from light source aging increases
Solution Approach 1:
The integrated photodetector is designed to perform multiple functions: it can detect both reference light intensity and measurement light intensity across different spectral bands. By making the photodetector universal and capable of handling both reference and measurement channels, the system eliminates errors associated with separate channels while maintaining gas species detection capability through spectral filtering and sequential measurement.
3Measurement precision
If reference photodetector is placed facing light source or reflector, then reference light wave measurement is improved, but device complexity increases
Solution Approach 1:
The patent extracts the need for complex reflector arrangements by integrating the reference measurement function directly into the measurement path. Instead of using separate reflectors to direct reference light to a separate photodetector, the system uses a single photodetector that can sequentially measure reference intensity and measurement intensity, eliminating the need for additional reflector components and simplifying the optical path.
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 configuration simplifies the design, reduces errors from light source aging, and enhances signal detection efficiency by eliminating the need for separate reflectors and channels, while maintaining accurate gas species concentration measurements.
Implementation Method 1
a light source extending over the cavity, able to heat up when passed through by an electric current, so as to emit infrared light
Implementation Method 2
an infrared-light sensor confined in a second component... such that the light source is arranged to emit a first portion of the light into the first half-space, and through the cover, and a second portion of the light into the second space, and through the substrate, toward the infrared-light sensor, the latter being able to detect an intensity of the light emitted by the light source
Implementation Method 3
The reference photodetector is usually associated with a reference optical filter. The reference optical filter defines a reference spectral band, in which the gas to be analyzed exhibits no significant absorption.
Data Source
AI summary
A device, for emitting and controlling infrared light, comprises a substrate extending between a bottom surface and a top surface. A cavity is provided in the substrate, the cavity opening onto the top surface. A light source extends over the cavity and is able to heat up when passed through by an electric current, so as to emit infrared light. A cover covers the substrate, the cover and the substrate forming a first component enclosing the light source. The light source delineates a first half space comprising the cover, and a second half space comprising the cavity and the bottom surface of the substrate.