Researchers at the University of Tokyo have designed a new filter that traps viruses without blocking airflow. The COVID-19 pandemic highlighted the need for effective masks, but fine mesh fabrics often restrict breathing.
Viruses are about 100 nanometers in size, so masks need very small pores to trap them effectively. Nonetheless, small pores typically reduce air permeability, causing discomfort for users.
The Tokyo team overcame this problem with a novel filter design using nanosheets made of porphyrins.
HOW THE FILTER WORKS
Porphyrins are flat, ring-shaped molecules with tiny central holes ideal for filtering gases.
These pores allow small gas molecules to pass freely but block larger particles like viruses.
The nanosheets made of porphyrins are layered on nanofiber-modified fabric with pores hundreds of nanometers wide.
This combination provides effective virus filtration while preserving air flow for user comfort.
The fabrication uses a process driven by the Marangoni effect, which controls the formation of nanosheets at the air–solvent interface.
TESTING AND PERFORMANCE
The researchers tested their filter following the standard N95 mask protocol. Results showed a filtration efficiency of 96%, surpassing the 95% benchmark for N95 masks.
The filter captured particles as small as viruses without significantly increasing breathing resistance.
This low differential pressure means users can breathe easily without sacrificing protection.
Senior author Kazuyuki Ishii emphasized the filter’s ability to trap nanoparticles while maintaining airflow.
PROMISING APPLICATIONS
The team’s approach, coating porous nanosheets on nanofiber fabrics, offers a promising path for future mask materials. It could lead to comfortable, high-performance masks that protect against viruses and other nanoparticles.
This innovation balances filtration and breathability, addressing a critical challenge in mask design. The study marks a significant step toward safer personal protective equipment for pandemics and air pollution.