Optical Hydrogen-Bonding Gas Sensor Using Azobenzene Isomerization
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Solution Overview
Problem
Conventional humidity sensors are susceptible to temperature variations, require regular recalibration, and are not suitable for harsh environments due to their reliance on permittivity changes and conductivity measurements, which limits their accuracy and durability.
Innovation Solution
An optically transparent matrix with hydroxyazobenzene derivatives is used to measure relative humidity and temperature by monitoring the thermal cis-trans isomerization kinetics, allowing for simultaneous measurement of multiple gases with a single sensor layer, eliminating the need for device-specific calibration and enabling remote operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional humidity sensors based on permittivity changes are used, then humidity measurement is achieved, but the sensors are susceptible to temperature variations and require regular recalibration
Solution Approach 1:
The patent replaces conventional electrical measurement methods (permittivity changes, conductivity measurements) with an optical measurement system. The sensing layer's optical properties (absorbance, reflectance, or fluorescence) change in response to humidity, and these changes are detected optically rather than electrically, eliminating temperature susceptibility and calibration drift associated with electrical methods
Solution Approach 2:
The invention utilizes changes in optical parameters (absorbance, reflectance, fluorescence intensity) of the sensing layer in response to humidity changes. The sensing layer contains compounds that undergo conformational changes or interactions with water molecules, resulting in measurable optical parameter variations that are stable across temperature ranges
2Ease of operation
If conventional humidity sensors with integrated electronics are used, then measurement capability is achieved, but clean room processes are required during manufacturing and remote sensing is difficult
Solution Approach 1:
The patent replaces integrated electronic measurement components with an optical measurement system. The sensing layer can be manufactured using standard coating techniques without clean room requirements, and the optical detection can be performed remotely through optical fibers or free-space optics, eliminating the need for electronic integration in harsh environments
Solution Approach 2:
The invention separates the sensing function from the detection function. The sensing layer is a standalone component that can be manufactured independently using simple coating processes, while the detection system can be located remotely. This extraction allows the sensing layer to be manufactured without clean room processes and enables remote sensing applications
3Measurement precision
If conductivity-based humidity sensors are used, then humidity measurement is achieved, but the sensors are susceptible to manufacturing variations and require chip specific calibration
Solution Approach 1:
The patent replaces electrical conductivity measurements with optical measurements of the sensing layer. Optical measurements are not affected by manufacturing variations in the same way electrical properties are, and the sensing layer can be manufactured with consistent optical properties using standard coating techniques, eliminating the need for chip-specific calibration
Solution Approach 2:
The sensing layer design provides universal response characteristics across different manufacturing batches. The optical properties of the sensing layer compounds are inherently stable and reproducible, allowing a single calibration curve to apply to all sensing layers manufactured using the same process, unlike electrical sensors that require individual calibration
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 approach provides accurate, stable, and cost-effective humidity and temperature measurement with a large dynamic range, suitable for harsh environments and remote sensing applications, reducing the need for recalibration and improving accuracy.
Implementation Method 1
following the thermal cis-trans isomerization kinetics of hydroxyazobenzene derivatives embedded into an optically transparent matrix
Implementation Method 2
it is illuminated periodically with light with wavelength capable of inducing trans-cis isomerization
Implementation Method 3
The isomerization is followed by measuring absorbance changes optically
Implementation Method 4
hydrogen-bonding molecules, which adsorb to the active sensing layer from the measurement environment
Data Source
AI summary
An optically transparent matrix including a molecule containing a hydroxyazobenzene group or its derivative embedded in the matrix. An optical system including the optically transparent matrix, an isomerizing light source, and one or more light detector(s) for measuring absorbance changes from the optically transparent matrix. A method for measuring the quantity of hydrogen bonding gaseous molecules.