Sol-Gel Optical Sensor for Diethyl Chlorophosphate Detection
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Solution Overview
Problem
Current optical chemical sensors face challenges in quickly and reliably measuring organophosphates due to issues with sensor membrane transparency, permeability, and indicator stability, which limits their sensitivity and selectivity, especially in environmental monitoring where continuous, on-site detection of low concentrations is needed.
Innovation Solution
A sol-gel membrane-based optical chemical sensor with immobilized 7-diethylamino-4-methylcoumarin as the indicator, using a combination of alkoxysilane tetraethylorthosilicate and methyltriethoxysilane, which is optically transparent, stable, and sensitive to diethyl chlorophosphate, allowing for fluorescence intensity changes to be monitored for analyte concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional sensor membranes are used, then the sensor structure is simple, but the membrane transparency and indicator stability deteriorate
Solution Approach 1:
The patent employs a composite sol-gel membrane system combining tetraethylorthosilicate (TEOS) and methyltriethoxysilane (MTES) with 7-diethylamino-4-methylcoumarin indicator. This composite approach creates a homogeneous matrix that simultaneously provides mechanical stability, optical transparency, and prevents indicator leaching, resolving the contradiction between reliability and structural simplicity.
Solution Approach 2:
The patent optimizes the molar ratio of TEOS to MTES (9:1) and controls sol-gel processing parameters (catalyst concentration, drying conditions, aging time) to achieve optimal membrane properties. These parameter adjustments ensure the membrane maintains transparency while providing sufficient structural integrity and indicator stability without excessive complexity.
2Reliability
If the sensor membrane is made transparent and stable, then the indicator stability improves, but the analyte permeability may worsen
Solution Approach 1:
The sol-gel membrane is prepared with controlled porosity through the sol-gel process, creating a network structure with interconnected pores. This porous structure allows small organophosphate molecules to diffuse through the membrane while the overall matrix maintains its stability and transparency. The pore size and distribution are controlled by the sol-gel composition and processing conditions.
Solution Approach 2:
The membrane exhibits different properties at different scales: at the macro level, it is transparent and stable; at the micro level, it contains pores for analyte transport. The sol-gel network provides structural stability while the nanoscale pores enable permeability, resolving the contradiction between stability and permeability through hierarchical structure design.
3Measurement precision
If the sensor is designed for high sensitivity detection, then the detection limit improves, but the response time may worsen
Solution Approach 1:
The patent achieves a detection limit of 0.69 µM with a response time of 600 seconds by optimizing the indicator concentration and sol-gel matrix composition. The balanced formulation allows sufficient indicator molecules for sensitive detection while maintaining adequate analyte diffusion rates, resolving the trade-off between precision and response time.
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 sensor achieves a detection limit of 0.69 µM with a linear concentration range of 187 nM to 22.8 µM and a response time of 600 s, enabling effective, real-time monitoring of organophosphate concentrations.
Implementation Method 1
The sensor active part is a sol-gel membrane, in which the indicator 7-diethylamino-4-methylcoumarin is immobilized. The sol-gel material of the sensor of the invention is based on a combination of alkoxysilane tetraethylorthosilicate and an organically modified siloxane methyltriethoxysilane.
Implementation Method 2
The interaction is reflected in the optical properties of the indicator, which shows the change in its fluorescence intensity.
Data Source
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AI summary
The present invention solves the technical problem of manufacturing process and design of optical chemical sensor, in which interaction of the indicator with the analyte allows quick and reliable spectrofluorimetric determination of organophosphates. The procedure for creation an optical chemical sensor with sol-gel membrane for detection of organophosphates, is characterized in that it begins with the preparation of the membrane so that the indicator C1, which is dissolved in ethanol (10-7 M), add tetraethoxysilane (TEOS) and methyltriethoxysilane (MTriEOS) and stirr in an ultrasonic bath for 10 minutes; to then add the catalyst solution (0.001 M HCI) and mix again in an ultrasonic bath for 20 minutes; to make coatings on the glass slides after 24 h of sol aging in a closed container at room temperature and so that the slide is dipped in the sol and slowly pulled out from it, and let to dry for 24 hours at room temperature to form a membrane; to wipe coating on one side slides before drying.