Research And Fabrication Of Self-powerd Integrated NO₂ Gas Sensor

Along with the rapid development of modern social economy and the rapid population growth,environmental pollution and energy shortage are becoming increasingly serious problems for all mankind.In order to solve the problem,the exploitation of gas sensing technology without additional power supply is of crucial importance for detecting harmful gases.More recently,self-powered environmental sensors driven by triboelectric nanogenerator?TENG?have attracted considerable interests due to their low cost,high sensitivity and pollution-free.In this sensor system the frictional charge as a clean and sustainable energy source shows many advantages,However,relevant research has rarely been reported.In this paper,based on the TENG technology,bionics principle and gas sensor technology,two kinds of flexible and integrated self-powered NO₂ gas sensors with small size,light weight and environmentally friendly were designed and fabricated,the corresponding sensing characteristics were investigated.The main contents are as follows:The simulation of the generator mechanism of TENG and the gas-sensitive response mechanism was carried out through the finite element simulation analysis software COMSOL.The latex films with good flexibility and the nylon materials with different frictional electrode properties were selected as the friction layer materials of the TENG to collect the kinetic energy of the flowing gas.The gas sensitive films were prepared by spraying the alkali-treated WO₃ nanoparticles on the nylon layer.The gas test platform was designed to simulate the gas flow process and provide gas flow energy for the self-powered gas sensor.A self-powered NO₂ gas sensor based on alveolar biomimetic structure was fabricated.The sensor working principle is based on the expansion and contraction of latex film under the action of air pressure as well as collection of the kinetic energy produced by flowing gas flow in the process of contact-separation of TENG.When the concentration of NO₂ gas rises,frictional charges on the nylon layer increases,and thereby enlarge the output voltage of TENG,and detecte the concentration of NO₂ gas according to the voltage change.The sensor showed good sensing properties to NO₂ gas.When the NO₂ concentration was 100 ppm,the response reached 732%.In various interfering gases,the sensor responds much better to NO₂ gas than other gases,more than 65 times response,indicating a good selectivity.A non-contact self-powered NO₂ gas sensor was researched and fabricated,and the alkali treated WO₃ was also selected as the sensitive material of the sensor.It consists of a latex balloon with a sensitive film on the inside and a cube-shaped shell with a hollow copper plate.The distance change between the latex ballon and the copper electrode during the expansion and contraction of the latex balloon induced an periodically varying potential difference,to achieve self-powered gas detection.When the concentration of NO₂ is 100ppm,the response of the sensor reaches 340%,and the response to NO₂ gas is more than 7 times higher than that of other tested gases.The gas sensitive film did not contact the friction layer during the working process,and thus showed good stability.