Fabrication Of Electret Nanofibers And Their Application For Wearable Healthcare Devices

Recently,inhaled transmission of the virus and severe air pollution have caused immeasurable harm to society,development,and people’s health is seriously threatened at all times.Wearable healthcare devices,especially lightweight,flexible and breathable wearable health protection devices and health monitoring devices have attracted widespread attention.The construction of high-performance wearable healthcare devices is of great significance for achieving effective personal protection,accurate and real-time health monitoring,and disease prevention.At this stage,researchers are focusing on how to improve the protection effect,monitoring capability,and providing effective energy to drive these devices.At present,the core of health protection devices is mainly melt-blown electret fiber membrane,which can capture the ultrafine particulate matter by relying on the charge stored inside the fiber.However,the existing melt-blown electret fiber usually has the features of wide diameter(micron level),small charge amount,and whose charge is unstable under high temperature or high humidity conditions.Therefore,the preparation of electret nanofiber membranes with stable and abundant charge is of great significance to achieve high efficiency and low pressure filtration.Meanwhile,the high-performance electret nanofiber membranes can be used to construct self-powered sensors to get rid of the dependence on energy supply devices and achieve mobile real-time health monitoring.In this paper,based on the charge storage mechanism of electret materials,we optimize the preparation process of environmentally stable electret nanofiber membranes with high charge storage capability and further design high-performance self-powered fiber-based wearable healthcare devices,which provide technical support for the performance optimization of electret materials and design ideas for the development of wearable healthcare devices.The specific research content and results are summarized as follows:(1)Polyetherimide electret nanofiber membranes with high-humidity stability were prepared using electrospinning and corona charging processes,which can be used to develop the self-powered health protection masks with smart indication function.After negative corona charging,this membrane has an excellent charge storage capability with a stable surface potential of-0.21 k V and remains relatively stable under 100 %RH humidity environment.Utilizing strong electrostatic effect,this membrane can efficient remove particulate matter with diameter of ～0.3 μm that is difficult for the filter with mechanical filtration mechanisms including interception effect,inertia effect,and diffusion effect.In addition,a fiber-based electret nanogenerator was constructed by using the high-performance polyetherimide electret nanofiber membrane,which can harvest the electrical energy converted by mechanical energy from the breath for lighting the liquid crystal display screen and indicating whether the mask has lost its function.This work has expanded the application of fiber-based electret nanogenerator in the field of self-powered flexible breathable wearable health protection devices.(2)Polytetrafluoroethylene electret nanofiber membrane with high charge storage capability can develop a real-time self-powered wearable health monitoring device.To overcome the processing difficulties caused by the insolubility of perfluoropolymer,a template-sacrifice method has been used to prepare.This membrane shows excellent mechanical properties which can be stretched to ～220%,and excellent charge storage capability with a stable surface potential of-0.61 k V is better than that of polyetherimide electret nanofiber membrane.Moreover,a high-performance fiber-based electret nanogenerator was constructed by using polytetrafluoroethylene electret nanofiber membrane which exhibited a high peak power of 56.25 μW.Accordingly,the fiber-based electret nanogenerator can be used as a self-powered wearable health monitoring device to real-time monitor human body movements and vital signs(such as respiration,heartbeat,and pulse),and demonstrating the application potential of fiber-based electret nanogenerator in the field of self-powered wearable health monitoring.(3)A hybrid perfluorinated electret nanofiber membrane with high temperature and humidity stability is prepared by constructing the nanoscale interfaces(as the charge traps)between low crystallinity fluorinated ethylene-propylene and high crystallinity polytetrafluoroethylene,which could assemble a self-powered multifunctional healthcare mask.Due to this as-obtained nanofiber membrane has stronger and more stable charge storage capability with a stable surface potential of-0.89 k V which is much better than pure perfluorinated electret nanofiber membrane,this mask achieves a highly efficient particulate matter(with diameter of ～0.3 μm)removal of ～99.712% with a low pressure drop of ～38.1 Pa,and is able to monitor the respiration signal in real time and offering a tachypnea warning on a mobile phone simultaneously.What’s more,the performance of this device is still relatively stable even under 100 %RH humidity and 92 ℃ temperature conditions.This research paves a new avenue for preparing high-charge-density electret materials and the design of multifunctional healthcare devices to realize wearable safe health protection and real-time health monitoring simultaneously.