Study On GFET Lactic Acid Concentration Biosensor Based On Lactate Dehydrogenase Modification

At present,the method of biosensor for the detection of lactic acid has the advantages of high specificity,high sensitivity,simple operation,fast and simple and so on.Therefore,the detection of lactic acid based on non-invasive biosensor technology has a broad application prospect in the field of sports medicine.Through the detection of the content of lactic acid in body fluid to adjust the training plan of athletes and prevent acidosis due to the high content of lactic acid.At present,the electrode types of lactic acid biosensor include screen printed electrode(SPE),glassy carbon electrode,gold electrode,platinum electrode,ITO plate-based electrode and carbon electrode.However,most of them can only be detected once and can not achieve reversible monitoring,so a graphene field effect tube sensor based on lactate dehydrogenase modified graphene field effect tube sensor for real-time monitoring of lactic acid was studied in this paper.The reversibility and reusability of the lactic acid sensor are verified.In addition,flexible wearable biosensors have become a research hotspot,but there is still a lack of theoretical research on the effect of flexible deformation to electrical properties of graphene.In addition,flexible wearable biosensors have become a research hotspot,but there is still a lack of theoretical research on the effect of flexible deformation on the electrical properties of graphene.Therefore,in this paper,the mathematical relationship between bending strain and graphene resistance change rate is established,and the variation of graphene electrical properties with bending strain is verified by experiments.In this paper,the sensing mechanism and electrical characteristics of graphene FET lactic acid sensor are analyzed,and the mathematical model of sensor response signal and lactic acid concentration is established.The structure of graphene FET lactic acid sensor was designed,and the process scheme of microelectromechanical system processing of the sensor was described.The PASE,lactate dehydrogenase and NAD+ enzyme modified on the surface of graphene were characterized by Raman spectroscopy,energy dispersive spectroscopy and electrical measurement.In this paper,a lactic acid sensor based on graphene field effect tube modified by lactate dehydrogenase was used to detect lactic acid molecules.Tween 80 reagent was modified on the surface of graphene to reduce the effect of non-specific binding on the electrical properties of graphene,and the effect on the electrical signal of graphene caused by the change of lactic acid PH was eliminated by differential means.In this paper,the lowest detection limit,detection range and response specificity of the GFET lactic acid sensor were studied.At the same time,in order to investigate whether the GFET lactic acid sensor can be monitored in real time and whether it can be reused,its reversibility and long-term stability were analyzed.In this paper,the resistance change of graphene under bending strain of flexible graphene FET sensor is studied theoretically,and the mathematical model of bending strain and graphene resistance change rate is established.At the same time,the changes of electrical properties of flexible graphene FET sensor under different bending strain were investigated by experiments.It mainly includes the effect of strain on graphene resistance,Dirac point in transfer characteristic curve and graphene transconductance.