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Prof. Yuekun Lai, Prof. Jianying Huang & Researcher Weilong Cai (Fuzhou University): Multiscale Nanofiber Filter Membrane TENG Technology Enables Efficient PM0.3 Filtration and Self-Powered Respiratory Monitoring
Air pollution, particularly ultrafine particles like PM0.3, poses severe health risks. Conventional high-efficiency filter materials often face a trade-off between filtration efficiency and breathing resistance, struggling to balance high performance, low energy consumption, and sustainability. Meanwhile, post-pandemic demands for smart respiratory monitoring and personalized health protection call for innovative multifunctional filter technologies.
This study develops a multiscale nanofiber filter membrane that optimizes fiber size and pore structure to provide high filtration efficiency with low breathing resistance. The team further integrated the membrane with a triboelectric nanogenerator (TENG), leveraging its electric field effect under airflow to enhance particle capture, achieving high-efficiency PM0.3 filtration. This "structural optimization + electric field enhancement" synergy overcomes the traditional efficiency-resistance trade-off. Additionally, TENG’s energy output enables self-powered real-time respiratory monitoring without external power.
Synergistic Enhancement for High-Efficiency PM0.3 Filtration
TENG’s electric field significantly boosts ultrafine particle (PM0.3) capture, achieving 99.37% filtration efficiency.
Low Breathing Resistance via Multiscale Nanofiber Design
Optimized fiber structure reduces breathing resistance while maintaining filtration performance.
Self-Powered Respiratory Monitoring
TENG converts breathing airflow into electrical signals for real-time respiratory rate and intensity tracking.
Flexible Structure for Diverse Applications
The membrane’s flexibility allows integration into smart masks, air purifiers, and health monitoring devices.
PA66 & PVDF-HFP Materials
PA66 and PVDF-HFP offer excellent film-forming and tunable properties, ensuring device performance.
This work fabricates a multiscale PA66/HACC composite nanofiber membrane via electrospinning, synergized with a PVDF-HFP nanofiber membrane to form a breath-driven TENG. The system combines electrostatic adsorption and physical interception, achieving >99% PM0.3 filtration at just 48 Pa breathing resistance. TENG’s self-powered output supports real-time respiratory monitoring with high environmental stability. This integrated system holds promise for air purification, smart protection, and health monitoring.
Figure 1: Formation and structure of the multiscale nanofiber membrane
As shown in Figure 1, researchers successfully fabricated ultrafine nanofiber membranes using electrospinning technology. By optimizing the physicochemical properties of the polymer solution, fiber performance was significantly enhanced. After adding the cationic polyelectrolyte HACC to the PA66 solution, the solution's conductivity increased nearly 30-fold, and viscosity rose, reducing fiber diameter to **72.34 nm** and forming a multiscale structure that dramatically decreased membrane pore size (minimum **1.20 μm**), thereby improving air filtration efficiency. Additionally, the fiber membrane exhibited excellent hydrophobicity (**water contact angle >134°**), effectively preventing moisture from affecting electrostatic filtration performance. The optimized **8 wt% HACC-doped sample** demonstrated superior spinning stability and filtration efficiency, offering new possibilities for high-performance air filters in medical and industrial applications.
Figure 2: TENG working principle and electrical properties of the fiber membrane
The research team innovatively developed a self-powered triboelectric nanogenerator (TENG) based on the PA66/H multiscale fiber membrane. By integrating PA66/H (positively charged) and PVDF-HFP (negatively charged) fiber membranes into a respiratory mask, they successfully converted human breathing energy into electrical signals (**peak surface potential: 6.14 kV**) through periodic contact-separation driven by airflow. By precisely controlling the **8 wt% HACC doping concentration**, the fiber membrane achieved both ultrafine pore filtration (**1.20 μm**) and outstanding triboelectric performance (significantly enhanced single-fiber electric field strength), while its porous structure ensured low airflow resistance.
Figure 3:Filtration mechanism and performance
As illustrated in Figure 3, the **self-powered PVDF-HFP@PA66/H filter** achieved a breakthrough **PM0.3 filtration efficiency of 99.37%** through the synergistic effects of **physical interception and electrostatic adsorption**. The electrostatic effect, generated by friction between the fiber membrane and PVDF-HFP layer, enabled the **8 wt% HACC-doped PA66/H membrane** to maintain a low airflow resistance of **48 Pa** while achieving an excellent **quality factor (QF) of 0.103 Pa⁻¹**. Remarkably, the filter retained **>98% efficiency even at 90% humidity**, demonstrating exceptional environmental stability. This dual-mechanism filtration (mechanical + electrostatic) provides an innovative solution for high-performance, low-energy air purification devices.
Figure 4: Comprehensive air filtration performance and comparisons
Further studies on the **self-powered filter’s overall air filtration performance** revealed that across airflow rates of **10–85 L min⁻¹**, the **PVDF-HFP@PA66/H filter** consistently maintained **>99% PM0.3 filtration efficiency**. Notably, the filter featured a **"self-recharging" capability**—after 30 minutes of use, a simple friction reactivation restored its **6 kV surface potential**, ensuring long-term stable performance. Even after multiple charge-discharge cycles, filtration efficiency remained high, highlighting its outstanding durability. Compared to existing technologies, this filter offers clear advantages in balancing efficiency and energy consumption, making it a promising solution for **medical protection and industrial air purification**.
Figure 5: Applications of the self-powered filter
Moreover, the **PVDF-HFP@PA66/H filter** integrated with **TENG technology** could accurately distinguish between **normal, rapid, and deep breathing patterns** via voltage signal variations, reflecting the wearer’s physiological state. The system innovatively incorporated **Bluetooth connectivity**, transmitting real-time respiratory data to a smartphone app for user monitoring. Additionally, the device could harness breathing energy to **self-power and illuminate 44 LEDs**. This breakthrough paves the way for **wearable health-monitoring devices**, with broad applications in **respiratory training, stress management, and sports monitoring**.
Paper Link: [https://doi.org/10.1016/j.gee.2025.05.001](https://doi.org/10.1016/j.gee.2025.05.001)
