Terahertz Sensor Humidity Measurement via Signal Ratio
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Solution Overview
Problem
Existing systems for measuring relative humidity are complex and prone to errors due to the need to account for multiple variables like water vapor concentration, temperature, and pressure, making real-time measurement challenging.
Innovation Solution
A TeraHertz sensor system that uses a combination of absorption and transmittance band signals to calculate relative humidity, with a method to ignore pressure dependence by using a temperature sensor and evaluating errors based on TeraHertz signals, allowing for simplified measurement through polynomial fitting of signal ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a system measures all three variables (water vapor concentration, temperature, and pressure) in real time, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates the pressure measurement component from the humidity measurement system. By using TeraHertz sensor signals that are inherently insensitive to pressure variations, the system removes the need for pressure sensors and pressure compensation algorithms, significantly simplifying the device while maintaining measurement precision through the use of absorption and transmittance band signal ratios
Solution Approach 2:
The TeraHertz sensor system performs multiple functions: it measures water vapor concentration through absorption band signals, provides temperature compensation through transmittance band signals, and inherently ignores pressure variations. This multi-functionality allows a single sensor system to replace what would traditionally require multiple separate sensors and complex integration
2Measurement precision
If a system uses multiple sensors to measure water vapor concentration, temperature, and pressure, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The patent removes the pressure measurement and compensation operations from the system. By selecting TeraHertz frequency bands where pressure has negligible effect on water vapor absorption, the system eliminates the need for operators to input or compensate for pressure data, making the system easier to operate while maintaining precision through automated temperature compensation using the signal ratio method
3Reliability
If a system accounts for all variables (water vapor concentration, temperature, and pressure) in real time, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent extracts and removes pressure as a variable from the humidity measurement calculation. By using the ratio of absorption band to transmittance band signals from the TeraHertz sensor, the system achieves reliable humidity measurements without pressure data, eliminating potential error sources related to pressure sensing and compensation while maintaining measurement reliability across varying pressure conditions
Solution Approach 2:
The patent changes the measurement approach by using TeraHertz frequency bands (0.1-10 THz) where pressure effects on water vapor absorption are minimal. By selecting specific absorption and transmittance bands within this range, the system transforms the measurement parameters to inherently ignore pressure variations, improving reliability without adding complexity
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 system effectively measures relative humidity with high accuracy by isolating temperature dependence and ignoring pressure variations, providing reliable results across different temperatures and pressures.
Implementation Method 1
A TeraHertz sensor may be used to detect electromagnetic radiation in an absorption band and a transmittance band
Data Source
AI summary
A first frequency of electromagnetic radiation and a second frequency of electromagnetic radiation are received at a detector. The first and second frequencies of electromagnetic radiation are transmitted through a medium within a frequency range of approximately 0.1 TeraHertz to approximately 10 TeraHertz. Signals are generated that are proportional to the transmittance of the frequencies of electromagnetic radiation through the medium. A ratio of the of the signals is formed, and one or more of a relative humidity, an absolute humidity, and a water vapor concentration of the medium are calculated as a function of a temperature of the medium, the ratio, and a set of functional parameters associated with the temperature of the medium.