Research On Fabrication And Performance Of Flexible Biochemical Sensor Based On Graphene Micro/Nano Structure

Many diseases are closely related to the abnormal concentration of the four substances of glucose,ascorbic acid（AA）,dopamine（DA）and uric acid（UA）.Therefore,the development of tools to detect the concentration of these small molecules is of great significance for investigating the normal life activities of organisms.Among many detection methods,electrochemical detection has many advantages,such as good selectivity,high sensitivity,and low cost,so it is widely used in small molecule detection.Recently,the main focus of electrochemical sensing research is the preparation and development of flexible materials.Graphene（GN）is widely concerned as an outstanding representative of carbon materials.Graphene has excellent catalytic performance and large specific surface area,which is very suitable for electrochemical sensing materials.Using thermal chemical vapor deposition method to prepare three-dimensional（3D）graphene nanosheets on soft carbon cloth（GNSs/CC）,and the active sites of graphene are used to further load the reaction center,successfully achieving ultra-sensitive detection of glucose and simultaneous electrochemical detection of AA,DA and UA.This dissertation mainly carried out the following two aspects around the graphene-based flexible biochemical sensor:Prepare graphene nanosheets with 3D structure and load glucose oxidase to prepare glucose oxidase/graphene/carbon cloth（GOx/GNSs/CC）electrode,which is applied to glucose detection,further realizing blood glucose detection of serum samples.Scanning electron microscope（SEM）showed that graphene with a 3D structure was uniformly coated on the surface of the carbon cloth fiber.The bare carbon cloth electrode and the carbon cloth electrode modified with graphene did not show the oxidation peak of glucose when detecting glucose,and the GOx/GNSs/CC electrode can realize the specific detection of glucose(85μA m M^-1 cm^-2of sensitivity).This result indicates that graphene with a 3D structure can provide sites for the loading of glucose oxidase,which provides a feasible way for the firm loading of the enzyme and the specific detection of glucose.To further advance the performance research of graphene flexible electrode materials,after removing glucose oxidase,it is planned to use graphene as the active center to detect three small molecules of AA,DA and UA at the same time.Prepare graphene with different thicknesses（GNSs/CC）and study their properties.SEM shows that as the growth time of graphene increases,the structure and morphology of graphene change accordingly.Compared with the bare carbon cloth electrode,the GNSs/CC electrode can detect three substances simultaneously and shows a higher peak current of oxidation peak.Furthermore,two methods of thermochemical vapor deposition and electrochemical deposition are combined to deposit gold nanoparticles on GNSs/CC to prepare gold nanoparticles/graphene/carbon cloth electrodes（Au NPs/GNSs/CC）utilizing the 3D structure of graphene.Differential pulse voltammetry realizes the ultra-high sensitivity detection(6230μA m M^-1 cm^-2) of uric acid by this electrode.