Designing Sensory Devices Based On Extended-gate Field-effect Transistor And Their Application Research

Field-effect transistor(FET)is a kind of electronic devices emerging in the field of biochemical sensing in recent years.It can convert the reaction generated during detection into an electrical signal and output it.It has the advantages of rapid detection,high sensitivity,small size and low cost.According to its own characteristics,various forms of FET have been developed to meet the needs of detection,among which the extended-gate FET(EG-FET)is a kind of FET,which sensing interface separate from the FET in order to avoid the liquid damage of the device.EG-FET not only has the advantage of high sensitivity of FET detection,but also its form of separation lays the foundation for the diversity of sensor interface design.At present,the biochemical sensors based on EG-FET as transducers are mainly focused on the "lock and key" oneto-one sensing principle to identify and detect the single substance.Therefore,it is of great significance for the development of the sensing potential of the EG-FET and the development of new analytical detection technology that using sensor materials to build high sensitivity biochemical sensors based on the sensing advantages of the EG-FET.The newly developed laser-induced graphene(LIG)technology in recent years can fabricate three-dimensional porous LIG electrodes in patterns,providing a new technical support for accurate batch fabrication of sensing materials.Methotrexate(MTX)is a kind of antifolic acid antitumor drug widely used in clinic.The accurate dosage of MTX in clinic is related to human safety and health.Therefore,it is of great significance to detect and analyze MTX or its metabolic content after administration.At present,the traditional analytical methods for detecting MTX have gradually become mature,so it is vital to develop a sensor with high sensitivity and convenient detection for the detection of drug MTX.In this work,EG-FET is used as the main transducer to build the sensor platform,and two kinds of sensor electrode arrays with different sensing principles are designed,which shows the application potential of EG-FET as the transducer.The first array explores the traditional "lock and key" mode of sensing detection,and realizes the specific recognition and real-time monitoring of small molecule drug MTX based on the aptamer-modified sensing gold electrode.On this basis,the different responses of LIG sensor electrode arrays based on different metal modifications to different substances were explored,which is expected to realize the simultaneous analysis and recognition of several substances such as small molecule drugs MTX and folic acid.Chapter 1 IntroductionThis chapter mainly introduces the sensing principle of the EG-FET,the advantages and disadvantages of sensing procedure,and the application in the field of biochemical sensing at present.The second is the formation principle of LIG,advantages as sensing materials and applications in the field of biochemical sensing.The third is determination of the significance of small molecule MTX,and significance of using EG-FET combined with MTX aptamer to identify and detect small molecule drugs MTX.Finally,the main content and research significance of this thesis are expounded.Chapter 2 Real-time monitoring of small molecule drug MTX based on EG-FET deviceIn this work,a portable device based on an aptamer-modified EG-FET sensor array was constructed for monitoring the small molecule drug MTX.This is the first time that EG-FET is combined with aptamer to complete the detection of MTX.The sensor array is designed for multi-channel simultaneous detection to improve detection efficiency.After detection,only the electrode array needs to be replaced.The extended gold electrode is connected to the aptamer by the thiol-gold bonds.The aptamer can recognize and capture the negatively charged MTX leading to the change of the potential on the electrode surface,and commercial FET perceives the change and output the electrical signal.Electronic signals are transmitted to mobile phone via Bluetooth,enabling real-time and wireless monitoring of MTX.Combining the advantages of FET and aptamer,the sensor achieves simple and efficient detection of MTX in a complex background,and can monitor the content of MTX in the serum of mice after different administration times,so it is expected to be applied in clinical monitoring.Chapter 3 Differentiation and recognition of several small molecule drugs by sensor array based on LIG-EGFETIn this work,a portable device based on LIG-EGFET sensor array was built,which metal particle modified LIG serves as extended gate.And the statistics measured by the device combined with principal component analysis method(PCA)can realize the identification of small molecule MTX,folic acid and other substances.In this work,the3 D porous LIG electrode with excellent sensing function was prepared by using LIG technology,and different metal particles were modified on the surface of the LIG electrode by magnetron sputtering.The sensing principle is to establish an "electronic tongue" sensing strategy,where differences in metal work functions regulate number of electrons transferred from each electrode in the sensor array to the graphene structure.This strategy avoids the preparation of multiple specific sensors and realizes the difference recognition of multiple molecular substances.In addition,the preparation cost of the sensor electrode is low and the process is simple,which can reduce the error of the detection data caused by the preparation process.These advantages make the sensor array platform expected to be applied in actual production.