Research On Water Quality Detection Based On Differential Sensitive Conductive Mechanism Sensor Array

The flow characteristics of the river bring some difficulties to realize the real-time water quality detection.It not only requires the detection instrument to provide water quality detection information,but also needs to realize the positioning and remote transmission of the collected water quality information data while meeting the requirements of small volume.This also puts forward the requirement of the sensor array to have the ability of small,low price and disposable,and also the ability to collect the overall information of water quality.Therefore,because of the characteristics of small,low cost and easy to modify,a modified electrode array with different conductive gradient is designed to collect the whole water quality information.Then,a small,floating and remote data transmission system is designed to cooperate with the sensor array.Finally,the information is analyzed by the pattern recognition algorithm,so as to classify and evaluate the water quality of the water source.Then,the water samples of different water sources are classified by different pattern recognition algorithms,And the conventional indicators of water quality detection in water source area are analyzed to analyze whether the conventional indicators such as potassium permanganate,total phosphorus,total nitrogen and ammonia nitrogen exceed the standard.The array of sensors with different sensitive conductivity(Au-SPE,Ag-SPE,rGO-SPE)was prepared.Firstly,gold nanoparticles,silver nanoparticles and reduced graphene(AuNPs,AgNPs,rGO)were modified on the surface of small screen-printed electrodes by electrochemical method.Three modified electrodes with different conductivity(Au-SPE,Ag-SPE,rGO-SPE)were prepared.The three electrodes form the conductivity difference gradient.The nanocomposite electrode array based on the screen-printed electrode base is constructed by using the conductivity difference gradient of the three electrodes.The cross sensitive array is formed to obtain the water sample information map.Then the electrochemical properties and surface morphology of the modified electrode were characterized by cyclic voltammetry(CV)and scanning electron microscopy(SEM).The experimental results show that the three materials are well modified to the surface of the electrode and the different conductivity is formed.Finally,the experiments show that the modified electrodes of Au-SPE,Ag-SPE and rGO-SPE have good repeatability and stability.At the same time,it is proved that the cross sensitivity of the sensor array can obtain the unique characteristic information of each water sample.A small differential pulse voltammetry system is designed.In order to realize the ability of floating and remote data transmission,the water quality detection instrument can also collect the data of the modified screen-printed electrode array.According to the hardware design principle of traditional electrochemical workstation,Bluetooth module and multi-channel sensor information module are added after miniaturization.The differential pulse voltammetry detection system used for water quality information collection is designed.It can cooperate with the sensor array to obtain the voltage and current information of water sample.According to the principle of electrochemical measurement,the system can apply voltage excitation to the sensor array surface with fixed waveform change,and collect the current signal generated by voltage applied on the electrode surface,and then transmit the collected signal to the computer through Bluetooth for the next data processing.The water samples from different surface water sources were collected by differential pulse voltammetry.The coefficient matrix of the current variation curve of each water sample is extracted by data fitting.On this basis,the main component analysis is used to process the characteristic data set to eliminate the problems of multiple collinear among data.Then,the qualitative classification of water samples from different water sources is realized by combining the methods of SVM,RF and PNN.Then,SVM was used to classify the water source by using the conventional indexes of potassium permanganate,total phosphorus,total nitrogen and ammonia nitrogen to analyze whether the water samples exceeded the standard.Because the current differential pulse voltammetry system designed in this paper has some problems to be solved,so it can’t be applied to the water quality detection site at present.But the method proposed in this paper can provide a way of thinking for the subsequent detection of the dynamic water quality of rivers and lakes,and it has great potential application.