Study On The Flexible Double Channel Graphene-based Biosensor For Diabetes Biomarker Detection

Diabetes and its complications,as one of the major non-communicable diseases,are characterized by abnormal glucose concentration in the body.Therefore,it is particularly important to study the sensor with continuous monitoring ability for glucose in human secretion.Graphene field effect sensor has the advantages of simple structure,high integration and fast response.It is often used in the detection of various biomarkers.It has important research significance and application value for disease prevention and diagnosis.In recent years,boric acid molecular probes used in the field of glucose sensing have gradually entered the vision of researchers,but there are still few reports on the boric acid graphene field effect tube sensor for detecting the concentration of glucose in solution,there is little research on the graphene field effect tube sensor in the field of glucose detection,and there is a lack of further exploration on the reaction principle between boric acid and glucose.At the same time,traditional blood glucose detection requires fingertip puncture,or the use of micro needles inserted under the epidermis to collect body fluids,which is easy to cause further infection in diabetes patients.And most glucose sensors are rigid sensors that can not fit the surface of human skin.The lack of research on the flexibility of sensors limits their application in real life.In this paper,aiming at the shortcomings in the theoretical and application research of wearable flexible graphene field effect tube sensor in glucose detection,through density functional analysis,taking boric acid graphene field effect transistor sensor as the research subject,the reaction between boric acid groups and glucose was studied,and the reaction energy at different binding sites was calculated.At the same time,the change of reaction energy between the boric acid group and glucose before and after the addition of graphene was calculated,and the influence of graphene on the whole reaction system was analyzed.The adsorption energy of typical impurity molecules in human secretion on the surface of graphene was calculated,and the detection ability of boric acid group for glucose in the presence of impurity molecules was obtained.The adsorption of various types of carbon ring molecules on the graphene surface is calculated,the charge transfer between them is analyzed,the surface modification mechanism of graphene is explained,and the theoretical model of field-effect transistor(FET)sensor considering graphene surface modification is established.The detection range,detection limit and equilibrium dissociation constant of liquid gate graphene FET sensor modified by boric acid monomer probe are analyzed.Compared with enzyme sensors,which cannot be stored for a long time and most non-enzyme sensors have harsh reaction conditions,this sensor has good glucose detection ability in the neutral buffer.At the same time,the repeated use,small deformation and long-term storage capacity of the sensor are studied.The influence of polymer probe components on the signal gain of the sensor was studied.Based on the modification method of boric acid monomers,a method of modifying boric acid monomers after polymerization by free radical polymerization is proposed.A variety of polymers with different proportions are configured,the influence of their ratio on the performance of the sensor is studied,and the polymer ratio with the largest signal gain is obtained.Compared with the sensor modified by boric acid monomer,the signal gain is increased by 157%,indicating that the polymer modification method can effectively improve the detection ability of the graphene FET sensor.At the same time,the sensing ability of the sensor is confirmed in the urine density analysis experiment.Based on polymer-modified glucose sensors,a graphene FET sensor with a thickness of only 1 μM multi-channel ultra-thin and ultra-flexible,which realizes the complete fit between the sensor and the human body surface,has been developed in this paper.It has the ability of deformation sensing and simultaneous detection of solution concentration.After the flexible sensor is deformed by largescale bending,folding and shrinkage,the changes in hole carrier mobility and electron carrier mobility are less than 2%,which maintains the electrical performance equivalent to that before deformation.After large deformation,the change of Dirac point of the sensor for the target with the same concentration remains stable.At the same time,the simultaneous detection ability of two different types of markers in solution are verified by experiments,which proves the application potential of the sensor in the clinic.The scene of glucose detection by the human body during exercise is simulated,which proves that the sensor has the ability to detect the movement state-body fluid glucose concentration at the same time,and solves the problem of simultaneous detection of glucose concentration in body fluid and exercise state for diabetics during exercise.