Research On Fabrication And Sensing Properties Of Graphene Field Effect Transistor

Graphene,a two-dimensional lattice-structured material composed of carbon atoms,possesses a myriad of unique properties,including exceptional electrical,thermal,mechanical,and optical characteristics.The unique structure and properties of graphene make it show great potential applications in the fields of electronics,energy,materials and medicine.Its bipolar properties and nanoelectronic conductance play an important role in the application of electronic devices,especially for graphene-based field effect transistor(G-FET).G-FET,boasting high electron mobility,rapid response times,and low power consumption,has wide application prospects in flexible electronics,sensors,and biomedical applications.In this thesis,a large-scale graphene film was prepared on Cu foil by chemical vapor deposition(CVD)method.The G-FET was successfully fabricated with graphene as the sensing material.The practical application study of G-FETs in the field of biosensing was further investigated by deeply exploring the properties of graphene material itself and the performance of G-FET devices.The main contents are as follows:(1)A sensor was developed for non-destructive real-time in situ whole-stage monitoring of organoids using G-FET.The sensor features high-quality graphene nanomaterials in the sensing channel,offering ultra-high carrier mobility,a large specific surface area,easy integration,and continuous real-time sensing capabilities.By employing liver organoids as a model,the integration of the organoid culture device with G-FET allowed for synchronous monitoring of organoid development and bioelectrical signals.The sensor exhibits high sensitivity,stability,and accuracy in detecting the organoid marker albumin,with a detection limit as low as 1 pg/m L.This integrated sensor device effectively minimizes intergroup differences between samples during real-time organoid monitoring,enabling kinetic modeling of organoid fate states and evaluating the impact of drugs on hepatocyte fate.Overall,the non-destructive real-time in situ FET(NDRS-FET)sensor shows great promise for real-time,accurate,and high-throughput biomolecular detection.(2)A novel biosensor based on surface enhanced Raman scattering(SERS)-FET dual sensing mode was developed by using AuNPs/graphene composite as sensing material to achieve the qualitative and quantitative detection of MC-LR.Based on the SERS sensing mode,the Raman fingerprint spectrum of MC-LR was obtained through the specific combination of MC-LR aptamer and MC-LR,and MC-LR was accurately identified and qualitatively detected.Based on the FET sensing mode,the sensitivity of the FET sensor for the detection of MC-LR was improved by using AuNPs/graphene as the sensing channel,and the detection limits in phosphate buffer solution(PBS)and human serum were as low as a M.In addition,the sensor was utilized for the detection of MC-LR in actual water samples,and the complex components in the water did not interfere with MC-LR detection,indicating a significant high specificity of the sensor.The SERS-FET dual-mode biosensor can provide more detection options and improve the reliability of measurement results,which may have a great application prospect in the field of water environment detection.(3)We designed a 3D crumpled G-FET sensor based on AuNPs modification for label-free and highly sensitive DA detection.The AuNPs/graphene composite structure was transferred to a heat-activated shape memory polymer flexible polystyrene film(PS)substrate for heat treatment to form a crumpled structure due to thermal shrinkage deformation,which was further developed into an ultra-sensitive FET sensor for DA detection in PBS,human urine and fetal bovine serum samples.The detection limits were as low as z M.On the one hand,the enhanced sensitivity is attributed to the nanoscale deformation of graphene,which increases the specific surface area andλ_D.On the other hand,the synergistic interaction of graphene with AuNPs facilitates the electron transfer and enhances the carrier concentration of graphene.This synergistic effect not only improved the conductivity of graphene,but also enhanced its hydrophilicity,which can significantly improve the ultra-sensitive detection of DA.Furthermore,the practical application accessibility of the sensor was successfully proved by detecting the DA release from pheochromocytoma PC12 cells under K~+stimulation.(4)To further expand the application of the crumpled G-FET sensors,the sensing interface was improved,and a crumpled G-FET sensor functionalized with L-polylysine(PLL)was successfully constructed for highly sensitive SARS-CoV-2 detection.Compared with the functionalization of crumpled graphene with AuNPs,the functionalization with PLL significantly improved the hydrophilicity of the sensor.Meanwhile,the electrical characteristics of the flat and crumpled G-FET sensors.Experimental results shown that the conductivity and carrier mobility of the crumpled G-FET were significantly increased by more than 7 times,its sensitivity was also increased by 2.67 times,and the detection limit was as low as 100 fg/m L.To confirm the specificity of the crumpled graphene sensor,PLpro analogs,as well as PLpro in artificial saliva and human serum,were examined.Results indicate that the sensor displayed excellent specificity and effectively recognized target molecules.In conclusion,the crumpled G-FET biosensor serves as a highly sensitive and specific tool for detecting SARS-CoV-2 biomarkers.