Study On Biosensor Based On CVD Graphene And Its Detection System

With the help of physical and chemical methods,biosensor---a device made by biological materials is utilized to detect substances.It has the advantages of high specificity,high sensitivity and high efficiency.It has great application value in environmental monitoring,life sciences and other fields.Graphene is a kind of new two-dimensional sheet-like material with unique physicochemical properties,which is a single atomic layer thick and is composed of carbon atoms arranged in a honeycomb-like structure.A new type of biosensor based on graphene not only enriches the construction material of the sensor,but also brings the inspiration with me.Based on the unique physicochemical properties of graphite,the research of field-effect tube biosensor is conducted in this paper.In Chapter One,the unique structure and properties of graphene are introduced,and the preparation methods of graphene are summarized.Then the research progress and status of the biosensor at home and abroad are introduced.The biosensor has become an important technology in the field of biochemical analysis because of its advantages,such as the high sensitivity,selectivity,accuracy,rapidity,low cost and operational and so on.In Chapter Two,a kind of integrated graphene field-effect transistor(IGFET)is designed and made.The grid electrode is made of a planar gold(Au)film,and the drain electrode and source electrode are made of indium tin oxide(ITO)electrode.Then,the planar Au grid electrode is integrated with the graphene FET,subsequently connected to an adjustable constant voltage source to generate a stable electric field between the grid electrode and the graphene,thereby modulating the channel conductance as well as the Ag/AgCl electrode.Since the channel conductance of graphene FET can be modulated,the equivalent resistance of the FET can be used as a signal obtained through a bridge circuit and a signal of a detection amplifier.The experimental results show that the equivalent resistance of FET decreases with the increase of the width of channel conductance,the decrease of the distance between the grid electrode and the graphene plate,and the increase of ATP concentration.In Chapter Three,a dual channel pH value field effect transistor is developed by using the unique optoelectronic properties of graphene.On one hand,grapheme FET shows a clear pH dependent type conductive characteristics which can produce current signals between the source electrode and drain electrode;on the other hand,addition of pH fluorescent probes in theelectrolyte solution can achieve the pH value fluorescence detection.A dual channel data acquisition system researched and developed independently,which is used to collect current and fluorescence signals simultaneously.The pH value of phosphate buffer solution(PBS)can be monitored in real time by using the dual channel data acquisition system and DGFET.