LED Optical Sensor for PAH Fluorescence Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional fluorescence sensors for measuring polycyclic aromatic hydrocarbons (PAHs) require high-intensity gas discharge lamps, which are large, energy-intensive, and complex to control, making them inefficient for determining small substance concentrations.
Innovation Solution
A compact optical fluorescence sensor using a light-emitting diode (LED) as a light source emitting modulated light at specific wavelengths, coupled with a detector and data processing unit that adjusts the duty cycle based on concentration, temperature, and transmission power to determine PAH concentrations, enabling efficient fluorescence measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If gas discharge lamps are used as light source, then excitation intensity is high, but device size is large, energy consumption is high, and control complexity increases
Solution Approach 1:
The patent replaces the gas discharge lamp (electromagnetic system requiring complex electrical control) with a light-emitting diode (LED). This substitution eliminates the need for complicated electrical control circuits while maintaining sufficient excitation intensity for fluorescence measurement, thereby reducing device complexity and energy consumption.
Solution Approach 2:
The patent employs modulation of the LED light source with variable duty cycles to optimize excitation intensity. By adjusting the duty cycle parameter, the system achieves appropriate excitation levels for different PAH concentrations without requiring high continuous power, thus reducing overall energy consumption while maintaining measurement capability.
2Illumination intensity
If gas discharge lamps are used as light source, then excitation intensity is high, but energy consumption increases
Solution Approach 1:
The LED replaces the energy-intensive gas discharge lamp, consuming significantly less electrical power while providing sufficient excitation light for fluorescence detection. This substitution directly addresses the high energy consumption issue.
Solution Approach 2:
The LED operates in a modulated manner with duty cycles ranging from 1% to 100%, allowing the light source to be activated only when needed for measurement. This periodic operation reduces average power consumption compared to continuous operation of traditional lamps.
3Use of energy by stationary object
If LED with duty cycle control is used, then energy consumption is reduced, but light intensity stability may be affected
Solution Approach 1:
The patent incorporates a monitor diode that provides feedback on the actual light output of the LED. The data processing unit uses this feedback information to adjust the duty cycle and compensate for intensity variations, thereby maintaining stable effective excitation intensity despite the modulated operation mode.
Solution Approach 2:
The system dynamically adjusts the duty cycle based on real-time conditions including temperature changes and aging effects. The data processing unit modifies the duty cycle parameter to maintain consistent excitation intensity throughout the LED's operational lifetime, compensating for natural degradation.
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 provides a low-energy, long-lasting, and compact sensor capable of accurately determining PAH concentrations, suitable for applications like flue gas scrubbing, while ensuring compliance with legal water quality standards by accurately measuring PAH content in wastewater.
Implementation Method 1
the light source comprises a light-emitting diode (an LED), wherein the LED emits transmitted light having a wavelength of less than 300 nm, for example, 255 nm and/or 270 nm
Implementation Method 2
the transmitted light is converted into received light by means of fluorescence in the medium as a function of the concentration of polycyclic aromatic hydrocarbons
Data Source
AI summary
An optical sensor for determining the concentration of polycyclic aromatic hydrocarbons in a medium incudes a light source configured to emit transmitted light having a wavelength of less than 300 nm into the medium; a detector for receiving received light, wherein the detector is configured at least for receiving received light having a wavelength of 300 nm to 400 nm, wherein the transmitted light is converted into received light by means of fluorescence in the medium as a function of the concentration of polycyclic aromatic hydrocarbons, wherein a detector signal is generated from the received light; and a data processing unit configured to determine the concentration of polycyclic aromatic hydrocarbons using the detector signal, wherein the data processing unit controls the light source such that the light source emits modulated transmitted light according to a duty cycle. Methods of using the optical sensor are further disclosed.