The Construction Of Self-powered Sensor Based On Triboelectric Nanogenerator And Its Application In Respiratory/Fire Monitoring

Triboelectric nanogenerator（TENG）is a power generation device that converts mechanical energy into electrical energy.Its working principle is the coupling effect of triboelectrification and electrostatic induction.Self-powered sensors based on triboelectric nanogenerators have the advantages of wide material selection,low cost,and multi-functional integration,and have broad application prospects in fields such as mechanical energy harvesting,healthcare,and environmental monitoring.However,affected by environmental factors,the output performance of TENGs in the process of converting mechanical energy is relatively low and unstable,which severely limits its practical application in complex environments.Therefore,improving the output performance is particularly important for the practical application of TENGs in complex environments.In this paper,the construction of self-powered sensor based on triboelectric nanogenerators and its application in respiratory/fire monitoring have been overall developed and studied.The specific research contents of the full text include the following points:（1）The conductivity,surface roughness,and adhesion of the electrode material to the friction material all affect the output performance of the TENG.Thus,the selection of electrode materials is also crucial.Silver metal materials with high electrical conductivity and antibacterial activity are the main candidates for the construction of TENGs,especially for the detection of weak respiratory signals and multifunctional applications of them.To realize self-powered respiration monitoring based on TENG,a single-electrode mode TENG was constructed using Ag micro-mesh as electrodes,electrospun PVDF nanofibers and PA6nanofibers as two friction layers.The TENG is particularly sensitive to weak mechanical vibration energy and can be used for respiration monitoring.Therefore,a reusable multifunctional mask based on Ag micro-mesh film for electrothermal sterilization and self-powered real-time breathing monitoring was developed.The highly conductive Ag micro-mesh films with continuous stretching spinning method display an excellent electrothermal sterilization performance,and can be used as TENG with working electrodes to prepare for real-time respiration monitoring.With the low driving voltage of 3.0 V,the surface temperature can quickly rise to above 60°C within 30 s,therefore the antibacterial efficiency of Staphylococcus aureus of electrothermal sterilization can reach 95.58%within 20 minutes,realizing the self-sterilization of medical masks.In addition,a self-powered alarm system based on TENG as a respiration monitor was developed for real-time respiration monitor,providing timely treatment for patients at risk of tachypnea and apnea.Therefore,this work paves a new practical way to realize personalized multifunctional masks for electrothermal sterilization and real-time respiratory monitoring in clinical medicine.（2）For TENG,which acts as a sensor itself,the output voltage is relatively low and the sensitivity is high,which is beneficial for the identification and monitoring of weak signals.However,in a sensing system where TENG acts as a power supply unit,a large output voltage can continuously power the entire system.In particular,in the face of harsh environment,the choice of friction materials and structure design have extremely high requirements.Therefore,we chose silica gel and copper foil with better stability and durability.In the application of the TENG-based self-powered forest fire alarm system（FFAS）,we constructed the TENG with a fully sealed spherical independent layer pattern using copper foil as the electrode,silicone ball as the friction layer and acrylic hollow sphere as the shell.The TENG can effectively collect wind energy and is not affected by harsh environment.In order to monitor forest fires effectively,we propose a FFAS based on the coupling of thermosensitive effect and triboelectric effect.FFAS makes a self-powered early forest fire monitoring and detection system by connecting spherical independent layer mode triboelectric nanogenerator（S-TENG）as power source,polydopamine-modified graphene oxide（P-GO）as thermosensitive sensor and commercial LED as alarms.When encountering an open flame or abnormally high temperature,the thermosensitive sensor based on P-GO can be thermally reduced in situ,causing a significant change in resistance.Therefore,the output voltage of the S-TENG can be adjusted by the impedance matching effect between the special output characteristics of the TENG and the working state of the thermosensitive sensor,and then the LED can be directly lit as an alarm.In addition,FFAS achieves low temperature response（160°C）and fast response time（～3 s）,especially without external power supply.Therefore,FFAS based on the impedance matching effect between TENG and thermosensitive sensors will provide real-time,fast-response,and self-powered monitoring strategies for early warning and detection of forest fires.（3）In addition to the electrode material,the modification of friction materials is the most effective way to improve the output performance of TENGs.In order to improve the output performance of TENGs,we used electrospun P（VDF-Tr FE）and PA6 nanofiber film as two friction layers,and aluminum foil as electrode to construct TENGs in contact separation mode.We took the material modification as the starting point to improve the output performance of TENG.Also,different dielectric materials were added to P（VDF Tr FE）ferroelectric polymer,including nano nickel oxide（NiO）,nano titanium dioxide（TiO₂）and nano barium titanate（BTO）.The addition of NiO and TiO₂ increases the dielectric constant of the P（VDF-Tr FE）composite nanofiber film,generating the increase of surface charge density and enhancing the ability of electron capture,and further improves the output performance of the TENG.As for BTO,except for improving the dielectric constant,BTO accelerates the formation of theβphase in the P（VDF-Tr FE）ferroelectric polymer under the electrostatic field,which increases the surface charge density and enhances charge capture ability of the nanofiber friction layer.As a result,the output performance of TENG is further improved,and the output voltage（about 300 V）of TENG is nearly 1.5 times higher than that without BTO added.