Research Of Electrochemical Sensing System Based On Concentration Cell And The Applications

In recent years,point-of-care testing(POCT)technology has been widely used in clinical diagnosis,family health monitoring and other fields because of its advantages such as fast detection speed,compact and portable device and no restriction of test site.POCT is of great significance in improving the efficiency of clinical diagnosis,improving the quality of life of patients,and reducing the pressure of outpatient services in hospitals.POCT is playing an important role in biomedical testing sites at all levels of clinics,communities,families and so on.Among them,POCT technology based on electrochemical sensing can quantitatively convert the concentration of the substance to be measured into electrical signals for measurement.It has the advantages of high sensitivity,simple operation,portable device and low cost.It has been successfully applied to personal household blood glucose monitoring.However,compared with traditional bioanalytical methods,electrochemical sensing still has some disadvantages in many aspects.For example,the presence of electrically active interfering substances in biological samples will bring great errors to the test results,traditional electrochemical sensing methods need to use precious metal electrodes.Although large-scale production can reduce the cost,it still limits its large-scale application.Therefore,it is of great significance to develop new electrochemical sensing principles and systems.In this work,a new electrochemical sensing method is developed based on the principle of concentration cell,and the sensing system is constructed and optimized.The system is applied to the detection of human physiological and psychological indicators to solve the problems of high background,large interference and complex operation of traditional electrochemical sensors.At the same time,a self-powered system based on the concentration cell principle is also developed,which is preliminarily applied to the power supply of wearable devices.The main research contents are as follows:(1)Based on the principle of concentration cell,an electrochemical sensing method for small biological molecules was developed and successfully applied to the quantitative determination of glucose in whole blood samples.The method catalyzes the oxidation of glucose by glucose oxidase and changes the concentration of redox electric couple on two electrodes.Thus,through the measurement of potential,the quantitative detection of glucose in whole blood is realized.Compared with the traditional electrochemical sensing system,this method is based on the principle of concentration cell,and measures the potential difference generated by the concentration difference between the two electrodes.It can significantly eliminate the sample background and interference and realize the whole blood electrochemical detection with minimum background.At the same time,the sensing system does not need precious metal electrodes,which greatly reduces the cost and has a good application prospect.We also built an electrochemical sensing system based on smart phone platform,and detected glucose,lactic acid and uric acid in human whole blood samples obtained by the hospital,which preliminarily verified its clinical application potential.(2)On the basis of work(1),we have developed a multi-step electrochemical sensing method for biological macromolecules.Inspired by the principle of mercury thermometer,this method adds a hydrophobic region in the siphon channel,shaking the sensor after the first step reaction,and the second step reaction started.We applied this method to the detection of saliva amylase.The two-step reaction required for the detection was completed on a sensing strip,without using additional instruments for reagent transfer,which greatly simplified the operation steps.Based on the on the POCT technology of saliva amylase,we assessed the psychological stress of many volunteers,and compared the saliva amylase detection results with the lie detection results,which provided a new idea for psychological research and mental disease diagnosis.(3)A self-powered method based on the principle of concentration cell is developed,which can be applied to the power supply of low-powered electronic equipment.Based on the principle of concentration cell,the method converts the concentration difference between high concentration salt solution and low concentration salt in sweat into electric energy,and collects and stores the electric energy through the printed circuit board(PCB),so as to build an self-powered system,so as to realize the power supply of low-power electronic equipment.Compared with the enzyme fuel cell method,this method has good stability,high reliability and can be used for a long time.It is expected to be applied in the field of wearable electrochemical POCT.