Research Into Improving The Performance Of Self-Powered Gas Sensors Based On Triboelectric Nanogenerators

With the development of sensor network technology,a large number of distributed gas sensors have put forward new requirements for their power sources.Traditional power sources have become an important factor restricting the development of gas sensor networks because of their high cost,large size,difficult to replace,and environmental pollution.The self-powered gas sensor can collect the energy in the environment and convert it into electrical energy while sensing,which is an effective way to solve the problem of power supply of the sensor network.Therefore,in-depth research on self-powered gas sensors is of great significance.The triboelectric nanogenerator（TENG）is a device that collects mechanical energy in the environment to generate electricity.It has a simple structure,low cost,and a wide range of energy sources.It is one of the ideal power sources for making self-powered gas sensors.In integrated self-powered gas sensors using TENG as power sources,the design of using gas-sensitive materials as friction layers has unique advantages due to its simple structure,small size,and easy fabrication.However,there are some issues that need to be addressed in this type of device.For example:（1）Semiconductor materials,as traditional gas sensing materials,are usually used as the friction layer of integrated selfpowered gas sensors based on TENG.However,since the friction layer of the integrated self-powered gas sensor cannot usually be encapsulated,the TENG with semiconductor material as the friction layer will respond to the light in the environment,especially ultraviolet（UV）light,resulting in an error response in the measurement.The stability of the integrated self-powered gas sensor of the generator under UV light is one of the problems to be solved.（2）At present,the detection limit of integrated self-powered gas sensors based on TENG is generally high.Therefore,how to improve the sensitivity of integrated self-powered gas sensors based on TENG is also an urgent problem to be solved.Focusing on the above two problems,this paper has carried out the following researches from two aspects to improve the stability and sensitivity of integrated selfpowered gas sensors.First,we designed and fabricated a self-powered ethanol gas sensor using an insulating polymer as the friction layer.Among them,we use an insulator material with a larger band gap instead of the commonly used semiconductor material as the friction layer.Since the insulator material cannot absorb photons to generate electron-hole pairs,UV light has no effect on its conductivity and gas adsorption on its surface.The performance of the device showed good stability under UV light irradiation,and its output voltage and its response to ethanol gas were not affected by UV light irradiation.This method effectively solves the problem that integrated self-powered gas sensors based on TENG are susceptible to UV light irradiation,and provides a feasible way to improve the stability of integrated self-powered gas sensors based on TENG in other environments.Then,the force of the gas molecules in the electric field is analyzed,and the influence of the electric field generated by the TENG on the gas adsorption and the sensitivity of the integrated self-powered gas sensor is studied.The response of the integrated self-powered gas sensor to various polar gases and non-polar gases was compared through experiments,and the relationship between the sensitivity of the integrated self-powered gas sensor and the electric field gradient was studied,and the conclusion was drawn: The electric field generated by the TENG is affected by the electric field force,which enhances the adsorption of gas on the surface of the friction layer and improves the sensitivity of the integrated self-powered gas sensor;increasing the electric field gradient can also enhance the gas adsorption and improve the sensitivity of the device.By designing the shape of the device,the electric field gradient of the integrated self-powered gas sensor is further enhanced,thereby improving its sensitivity.Due to the widespread presence of electric fields in TENG,this method can be widely used in integrated self-powered gas sensors fabricated from various materials.