Gas-Permeable Polymer Waveguide for Compact NDIR Gas Sensing
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Solution Overview
Problem
Conventional NDIR gas sensors face limitations in design and implementation due to complex processes, high costs, and physical space constraints, particularly in ensuring smooth gas flow and efficient contact between optical signals and gas particles within the optical cavity.
Innovation Solution
A non-dispersive infrared gas sensor using a gas-permeable polymer optical waveguide eliminates the need for separate inlet and outlet openings by allowing gas to naturally penetrate the waveguide, utilizing total internal reflection and band pass filters to measure gas concentration with a simple structure and improved sensitivity through bending structures and end mirrors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional optical cavity structure is used, then gas flow control can be achieved through inlet and outlet openings, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent removes the complex inlet and outlet openings from the optical cavity structure. Instead of having separate gas inlet and outlet openings, the design uses a gas-permeable polymer waveguide that allows gas to diffuse through its walls, eliminating the need for separate flow control structures and simplifying the overall device architecture.
Solution Approach 2:
The patent employs a gas-permeable polymer material for the optical waveguide. This porous or permeable material allows gas molecules to diffuse through the waveguide walls while maintaining optical transmission. This approach replaces the conventional sealed cavity with openings, achieving gas flow control through material properties rather than structural openings.
2Use of energy by moving object
If conventional optical cavity with total internal reflection is used, then optical signal transmission can be achieved, but physical space constraints limit optical path length
Solution Approach 1:
The patent transitions from a planar optical cavity design to a three-dimensional waveguide structure. By confining the optical signal within the walls of the polymer waveguide using total internal reflection, the system achieves extended optical path length in multiple dimensions, effectively increasing the interaction volume without proportionally increasing the device footprint.
Solution Approach 2:
The optical waveguide is nested within the polymer material structure. The waveguide walls themselves become the optical path, with the optical signal traveling through the polymer material. This nesting approach allows the optical path to be embedded within the gas-permeable structure, maximizing space utilization.
3Measurement precision
If gas enters and exits through openings in optical cavity, then gas concentration measurement can be performed, but manufacturing precision and sealing requirements increase
Solution Approach 1:
The patent eliminates the need for precisely aligned inlet and outlet openings by using a gas-permeable polymer waveguide. The gas measurement function is achieved through diffusion through the waveguide walls rather than through separate openings, removing the manufacturing precision requirements associated with opening alignment and sealing.
Solution Approach 2:
The gas-permeable polymer material provides a uniform, isotropic gas transport mechanism that does not require precise manufacturing of openings. The permeability property of the polymer material itself provides the gas flow control, eliminating the need for precision-engineered openings and associated sealing requirements.
4Measurement precision
If optical path length is increased to improve sensitivity, then gas concentration detection accuracy improves, but device volume increases
Solution Approach 1:
The patent achieves extended optical path length by utilizing the three-dimensional waveguide structure within the polymer material. The optical signal bounces along the waveguide walls in multiple dimensions, allowing the optical path to extend beyond what would be possible in a simple linear configuration, thereby improving sensitivity without proportionally increasing device volume.
Solution Approach 2:
The optical waveguide is nested within the polymer material, allowing the optical path to be embedded within the gas-permeable structure. This nesting approach maximizes the use of available space, allowing the optical path to be extended within the constraints of the overall device volume.
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 gas sensor achieves efficient gas concentration measurement without physical space constraints, enabling low-cost manufacturing and high sensitivity by optimizing optical path length and contact with gas particles, suitable for detecting harmful gases in fire and industrial environments.
Implementation Method 1
a optical waveguide 210 made of a gas-permeable polymer
Implementation Method 2
the optical signal travels through the optical waveguide of gas-permeable polymer by total internal reflection
Implementation Method 3
specific gas molecules absorb light of a specific wavelength
Implementation Method 4
measures gas concentration by using the characteristics that specific gas molecules absorb light of a specific wavelength
Data Source
AI summary
The disclosure relates to a non-dispersive infrared (NDIR) gas sensor which detects the concentration of gas with a simple structure and method by manufacturing an optical waveguide with a gas-permeable polymer material instead of a conventional cavity or chamber type. An optical signal travels through the optical waveguide of gas-permeable polymer by total internal reflection, and the gas naturally penetrates the optical waveguide without the use of separate inlet and outlet openings, so that the optical signal and gas particles come into contact with each other within the optical waveguide. Since the optical signal detected by a photodetector at the other end of the optical waveguide after traveling while contacting the gas particles has properties changed according to the concentration of the gas which they have contacted in the optical waveguide, it is possible to measure the concentration of a specific gas from the detected optical signal.