Preparation Of Fiber-based Organic Electrochemical Transistor And Research On Its Human Metabolite Sensing Performance

With the gradual development of society,human beings pay more and more attention to their own health.Many metabolites and chemical substances in human body fluids are closely related to human health and are the basis for diagnosing many diseases;development of fast and simple Sensors for detecting metabolites in human body fluids are currently the hotspots of research by researchers;organic electrochemical transistors(OECTs)are unique due to their maneuverability in water environment,ease of manufacturability,and uniqueness compared with traditional electrochemical sensors.Advantages,and are more and more widely studied and applied to sensors.In particular,fiber-based organic electrochemical transistors(FECTs),due to the high specific surface area of the fiber and the characteristics of fiber-based devices that are easy to be woven into the fabric and highly integrated,often have excellent sensitivity and have very strong advantages in sensing applications..In this thesis,a method for preparing polyethylenedioxythiophene(PEDOT)by modifying carbon materials on fiber-based materials was developed,and based on the composite materials,FECTs were prepared and two highly sensitive transistor sensors were constructed.The main research work of the thesis is as follows:(1)Use sodium dodecyl sulfate(SDS)as a dispersant to disperse carboxylated multi-walled carbon nanotubes(CNT)to prepare CNT/Cotton fibers,and then use chemical solution in-situ polymerization to prepare PEDOT/ CNT/Cotton conductive fiber,and the fiber has been tested by SEM,FTIR,XRD and tensile.Studies have shown that CNT increases the specific surface area and reaction sites of cotton fibers,and induces a uniform and dense conductive network of PEDOT nanowires on the fibers.XRD shows a highly ordered structure of PEDOT,and the tensile results show that conductive fibers Possess good mechanical properties.Immediately,the fiber-based organic electrochemical transistor was assembled with the prepared PEDOT-CNT-Cotton conductive fiber,and the electrical performance of the transistor was studied.The transistor has a high transconductance of 10.6m S,an on/off ratio of about 240 and a good switching curve,and the switching response time is very short,0.5 s.Afterwards,an ion selective membrane was coated on the channel of the organic electrochemical transistor to construct a transistor sensor.The sensor based on the organic electrochemical transistor was tested for its ability to sense potassium,sodium and calcium ions.The results show that the sensor can monitor potassium,sodium and calcium ions from 1–1000 n M;the detection limit is as low as 1 n M,fast response speed,linear coefficient reached 0.94;after coating potassium ion selective membrane,the sensor obtained good selectivity and repeatability.The prepared sensor can also be integrated into a fabric by hand weaving,which provides a promising scientific research platform for wearable medical monitoring.(2)The cotton fiber is soaked in the graphene oxide(GO)dispersion to prepare the GO/cotton fiber,and then the reduced graphene oxide(r GO)/cotton fiber is obtained by gas-phase reduction.Finally,the inverse microemulsion method was used to induce the formation of PEDOT nanostructures on the surface of the modified fiber.SEM results showed that the obtained PEDOT showed a flower-like morphology on the surface of the fiber.The conductive fiber was made into a fiber-based organic electrochemical transistor and its transistor performance was tested.It was found that the resulting transistor has very excellent output,transfer,and switching curves,with an excellent transconductance of up to 17.6 m S and a high switching ratio close to 300.At the same time,the research uses carbon cloth fiber as the substrate electrodeposition to prepare PEDOT-carbon fiber,and uses it as the gate electrode to test the transistor performance.The transistor also shows good basic performance,with a switching ratio of 300 and a high of 15.6m S.Transconductance.Finally,we used electrodeposition on different conductive fibers,using dopamine hydrochloride as the monomer and uric acid as the template to prepare a molecularly imprinted polymer film of uric acid.The fiber electrode deposited with the molecularly imprinted polymer film was used as the grid.After eluting the template,a fiber-based organic electrochemical transistor-based uric acid sensor was prepared,and uric acid was detected.The study found that the uric acid sensor with PEDOT-carbon fiber as the grid has the best response,and the detection range is1-1000 n M,The current change response is obvious,and the change range is large;at the same time,it has good reproducibility and selectivity;the linear coefficient is 0.96.At the same time,our fiber-based electrochemical transistors can also be integrated into fabrics for testing by sewing,and good testing results have also been obtained.