Solid-State UV Sensor for Nitrate Ion Measurement
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Solution Overview
Problem
Existing optical nitrate ion sensors face challenges with high cost, large size, high power consumption, and unreliability due to the use of complex gas-filled light sources and inefficient bandpass filters, making them unsuitable for widespread deployment in nitrate ion concentration measurement in water.
Innovation Solution
A solid-state light emitting component, such as a light-emitting diode (LED) or laser diode, is used to measure the transmittance of light with wavelengths less than 240 nm, stabilizing the central wavelength against variations in operating conditions and incorporating frequency-converting elements to improve reliability and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gas-filled light sources (xenon or deuterium lamps) are used to generate ultraviolet radiation with wavelengths less than 240 nm, then the absorption by nitrate ions is sufficient for measurement, but the device complexity, size, and power consumption increase significantly
Solution Approach 1:
The patent replaces complex gas-filled light sources (xenon or deuterium lamps) with a solid-state light source system comprising a visible or near-ultraviolet LED and a frequency-doubling crystal. This substitution eliminates the need for high-voltage power supplies, gas handling systems, and complex optical filtering, thereby reducing device complexity while maintaining the capability to generate and detect ultraviolet radiation at wavelengths less than 240 nm for nitrate ion measurement
Solution Approach 2:
The patent changes the operating parameters of the LED by driving it at high current densities (greater than 100 A/cm²) to enable efficient frequency-doubling in the nonlinear optical crystal. This parameter change allows the system to generate ultraviolet radiation at wavelengths less than 240 nm that are strongly absorbed by nitrate ions, achieving measurement precision comparable to gas-filled lamp systems but with simpler hardware
2Measurement precision
If gas-filled light sources are used, then ultraviolet radiation with wavelengths less than 240 nm can be generated, but the power consumption becomes excessively high
Solution Approach 1:
The patent replaces power-hungry gas-filled light sources with a solid-state LED-based system. LEDs inherently consume less power than gas discharge lamps, and when combined with efficient frequency-doubling in a nonlinear optical crystal, the system achieves sufficient ultraviolet radiation output for nitrate ion measurement at significantly reduced power consumption levels
Solution Approach 2:
The patent employs periodic pulsing of the LED at high current densities to enable efficient frequency-doubling in the nonlinear optical crystal. This periodic action allows the system to generate the necessary ultraviolet radiation bursts for measurement while minimizing average power consumption compared to continuous operation of gas-filled lamps
3Measurement precision
If bandpass filters are used to select specific wavelengths, then measurement accuracy is improved, but the device complexity and cost increase
Solution Approach 1:
The patent replaces complex bandpass filter systems with a simpler wavelength selection approach using the inherent emission characteristics of the LED combined with frequency-doubling in a nonlinear optical crystal. The crystal naturally generates ultraviolet radiation at specific wavelengths through the nonlinear optical process, eliminating the need for additional filtering components while maintaining wavelength selection accuracy for nitrate ion measurement
4Device complexity
If solid-state light sources are used, then device size and power consumption are reduced, but wavelength stability against operating condition variations deteriorates
Solution Approach 1:
The patent replaces the unstable wavelength output of simple LEDs with a frequency-doubling system using a nonlinear optical crystal. The frequency-doubling process inherently stabilizes the output wavelength at twice the fundamental frequency, providing more stable ultraviolet radiation wavelengths for nitrate ion measurement while maintaining the compactness and low power consumption of solid-state technology
Solution Approach 2:
The nonlinear optical crystal acts as an intermediary between the LED and the nitrate ion sample. The crystal converts the LED's visible or near-ultraviolet radiation into stable ultraviolet radiation at wavelengths less than 240 nm through frequency-doubling, thereby stabilizing the wavelength output while maintaining the benefits of solid-state light sourcing
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 results in lower cost, smaller size, improved robustness, and reduced power consumption, providing accurate and reliable nitrate ion concentration measurements with improved linearity and ease of calibration.
Implementation Method 1
A first light source, including a solid-state light emitter, emits light including one or more wavelengths less than 240 nm
Implementation Method 2
A solid-state light emitting component, such as a light-emitting diode (LED) or laser diode
Implementation Method 3
incorporating frequency-converting elements to improve reliability and accuracy
Implementation Method 4
A first photodetection means measures a power of the transmitted light
Implementation Method 5
The concentration of nitrate ions can then be calculated from the measured transmission of light through the sample and the well-known Beer-Lambert law
Implementation Method 6
Existing optical nitrate ion sensors rely on the direct absorption of ultraviolet light by the nitrate ion
Data Source
AI summary
A sensor for measuring a concentration of a particular ion, molecule or atom in a fluid includes a sample handling portion for providing at least some of the fluid, a first photo-detection device, and a first light source. The first photo-detection device is configured to measure a power of light incident thereon, and the first light source includes a solid-state light emitting device. The first light source is configured to emit light having a wavelength less than 240 nanometers incident on the fluid provided by the sample handling portion, and the first photo-detection device is configured to receive light having passed through the fluid.