Research On Au/TiO₂/PEDOT-SAW Gas Sensor With Dual Response Of Humidity And Carbon Dioxide

Humidity indicators have important meanings in the electronics industry and people's daily lives.Carbon dioxide gas is the main source of greenhouse gases.The increase in carbon dioxide emissions has become an environmental problem that plagues mankind.The detection of carbon dioxide and the control of carbon dioxide levels within a certain range have also become the people's demand for a better life.The surface acoustic wave technology originated in the 1880s.With the development of semiconductor technology and other industries,the surface acoustic wave has gradually transitioned from military radar with a high application technology platform to the civilian communications industry,the Internet of Things industry,and weather forecasting.Industry^[1],sensor industry and so on.Surface acoustic wave gas sensors have gradually become the key research direction of a new round of sensors due to their relatively low cost,small energy consumption,sensitive response,large range,and strong anti-interference ability.In this paper,a delay line surface acoustic wave(SAW)gas sensor with Au/Ti O₂/PEDOT composite as the sensing film is designed and prepared.The sensor's response to humidity and carbon dioxide,also the recognition mechanism are studied,and two The quantitative response model of the author.The mixed suspension of tetrachloroauric acid,titanium dioxide nanoparticles and 3,4-diethylenethiophene was used as the precursor.The Au/Ti O₂/PEDOT composite sensor film was prepared by photocatalysis,and the morphology of the sensitive film was analyzed.Microstructure and composition.In addition,the Au/Ti O₂/PEDOT sensing film was adhered to the SAW delay zone to construct a SAW gas sensor,and the response mechanism of the sensor to humidity and carbon dioxide was studied.The Au/Ti O₂/PEDOT sensing film has a porous structure,which can adsorb a large number of gas molecules;and there is a reversible bidirectional conversion ability between the reduced state and the oxidation state of PEDOT,which will change the conductivity of the sensing film.Therefore,the Au/Ti O₂/PEDOT-SAW sensorresponds to humidity with a mass loading effect,and the acoustic-electric effect under light conditions responds to carbon dioxide.Because the two response frequency shift directions are different,it can effectively identify humidity and carbon dioxide.The SAW gas sensor has a response range of 5 to 90%RH for humidity,a sensitivity of 0.034%RH Kz^-1in a relative humidity range of 5 to 50%,and a sensitivity of 0.218%in a relative humidity range of 55%to 90%.RH Kz^-1.The response range for carbon dioxide gas is 500 ppm to 70,000 ppm,and the sensitivity reaches 0.003 k Hz ppm^-1in the concentration range of 500 ppm to 2000 ppm.The sensor has good sensor performance and is suitable for the development of medical equipment and industrial equipment that simultaneously detect humidity and carbon dioxide.