Airborne pathogens pose a significant threat to public health, causing various respiratory illnesses. Current air disinfection technologies, such as HEPA filtration, suffer from limitations including only physical separation without inactivation, substantial pressure drops, and high energy consumption. Electroporation, using strong electric fields to disrupt microbial structures, offers a promising alternative. Nanowires enhance the localized electric field, improving efficiency, but microbial transport remains a challenge, especially in high-flow environments. Triboelectric nanogenerators (TENGs) provide a self-powered solution, converting mechanical energy into electricity. However, their application in air disinfection, particularly at high airflow rates and for virus inactivation, has been limited. This research introduces a self-powered air disinfection system that addresses these challenges, integrating a TENG with a nanowire-enhanced electroporation mechanism to achieve rapid and efficient inactivation of airborne bacteria and viruses.

Existing air disinfection methods, such as HEPA filtration, UV radiation, and photocatalytic disinfection, have limitations in terms of microbial inactivation efficiency, pressure drop, energy consumption, and throughput. HEPA filters only separate pathogens and do not inactivate them, leading to potential recontamination. UV radiation and photocatalytic disinfection methods require significant energy input and may have low throughput. Electroporation, using electric fields to damage microbes, presents a more effective approach, and nanowire-assisted electroporation has shown efficacy in water disinfection. However, its implementation in air disinfection faces challenges due to fast airflow rates. TENGs offer a self-powered alternative for water disinfection, but their application in air disinfection remains largely unexplored, especially for viruses. This study builds upon the existing literature, aiming to develop a self-powered, high-efficiency air disinfection system that overcomes the limitations of current technologies.

The study developed a resonance-vibration-driven (RV) air disinfection system comprising three main components: a vibration-driven TENG (V-TENG), a power management system, and a three-electrode disinfection filter. The V-TENG's resonance frequency was designed to match the ventilator's vibration frequency (~30 Hz) for optimal energy harvesting. The three-electrode filter consists of a multi-layer stainless-steel macro-mesh negative electrode, a copper-phosphide-nanowire-modified copper (Cu3PNW-Cu) positive electrode, and a stainless-steel ground electrode. The Cu3PNWs were synthesized via a two-step process: electrochemical anodization to grow copper hydroxide nanowires (Cu(OH)2NWs), followed by phosphidation. The system's operation involves three steps: (1) negative charging of microbes at the macro-mesh electrode; (2) electrostatic trapping of charged microbes on the Cu3PNW-Cu electrode; and (3) electroporation-mediated inactivation by the enhanced localized electric field near the nanowire tips. The V-TENG's performance was characterized by measuring voltage and current at different frequencies and amplitudes. The disinfection efficiency was evaluated using Escherichia coli (E. coli), Bacillus subtilis (B. subtilis), and MS2 bacteriophage as model organisms. Airflow rate, humidity, and microbial concentration were controlled and monitored. Disinfection efficiency was determined using standard microbiological techniques. The contribution of the macro-mesh electrode was assessed by comparing disinfection performance with and without the charging step. Airflow simulation was conducted to determine the contact efficiency of the macro-mesh electrode. Electric field simulations were performed to understand the field enhancement effect of the nanowires. The disinfection mechanism was investigated by examining the effects of radical scavengers, intracellular reactive oxygen species (ROS), copper ion release, and Joule heating. Morphological analysis using SEM and TEM was conducted to visualize microbial damage after disinfection.

The developed RV-disinfection system achieved remarkable results: >99.99% inactivation of E. coli, B. subtilis, and MS2 at an airflow rate of 2 m/s (treatment time of 0.025 s) and a pressure drop of only 24 Pa. The V-TENG effectively generated sufficient power (maximum 125 W/m²) at the resonance frequency (30 Hz) and various amplitudes. The multi-layer macro-mesh negative electrode ensured high contact efficiency (>99%) for both bacteria and viruses, leading to efficient charging and trapping. The Cu3PNW-modified electrode significantly enhanced the localized electric field (>10⁷ V/m), crucial for electroporation. Experiments revealed that electroporation is the primary disinfection mechanism, while chemical oxidation, ROS generation, copper ion toxicity, and Joule heating had negligible contributions. Morphological analysis confirmed electroporation-induced damage to both bacteria and viruses. The system demonstrated efficient disinfection under varying humidity conditions and for intermittent microbial bioaerosols. Compared to existing air disinfection methods, the RV-disinfection system shows significantly improved performance in terms of speed and airflow rate while maintaining low pressure drop.

The results demonstrate a highly effective and self-powered air disinfection system that overcomes many limitations of existing technologies. The integration of a V-TENG with a nanowire-enhanced electroporation mechanism offers a rapid, energy-efficient, and scalable solution for air disinfection. The use of a macro-mesh electrode allows for high-efficiency microbial charging and trapping, crucial for achieving disinfection at fast airflow rates. Electroporation is confirmed as the primary mechanism, showcasing the technology's potential for broad-spectrum microbial inactivation. The low pressure drop ensures minimal disruption to ventilation systems, making it highly suitable for integration into existing building infrastructure. The findings have significant implications for public health, offering a promising technology to mitigate the risk of airborne infections in various settings.

This research successfully developed a high-performance, self-powered air disinfection system that achieves rapid and efficient inactivation of airborne bacteria and viruses. The integration of a V-TENG with a nanowire-enhanced electroporation mechanism, combined with a rationally designed macro-mesh electrode, resulted in a system with superior performance compared to existing technologies. Future research could explore different nanowire materials, optimize the electrode design, and investigate the system's performance in real-world scenarios to further improve its efficiency and scalability.

While the study demonstrates the system's high efficacy under controlled conditions, further research is necessary to assess its long-term durability and stability. The performance evaluation was conducted using specific model organisms; additional testing with a wider range of bacteria and viruses is needed to confirm its broad-spectrum efficacy. The system's performance under varying environmental conditions (e.g., temperature fluctuations, presence of particulate matter) should also be investigated. The scalability and cost-effectiveness of manufacturing the nanowire-modified electrodes need further evaluation for widespread application.