Cleaner air with nanofibres

21 March 2017 | Research
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A non-woven mesh (right), when applied with the researchers' concoction (left), becomes a thin, see-through air filter

An NUS Engineering research team has created a novel nanofibre solution that easily creates thin, see-through air filters which can remove up to 90 per cent of PM2.5 particles and achieve high air flow of 2.5 times better than conventional air filters. Their invention was published in the online version of scientific journal Small in December 2016.

The research team was led by Assistant Professor Tan Swee Ching from NUS Materials Science and Engineering, which comprised Asst Prof Tan’s PhD student Sai Kishore Ravi and Dr Varun Kumar Singh, who was formerly with NUS Materials Science and Engineering.

The researchers engineered organic molecules from phthalocyanine, a chemical compound commonly used in dyeing, which can self-organise, similar to the stacking of building blocks, to form nanoparticles and subsequently, nanofibres. The nanofibres are suspended in liquid and easily “cling” onto non-woven mesh when applied. Improved air filters can be quickly produced by simply spreading the novel concoction onto a non-woven mesh and leaving it to dry naturally. An additional benefit of the eco-friendly air filter is that it enables natural lighting and visibility even as it blocks harmful damaging ultraviolet (UV) rays.

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Sai (right) applying the nanofibre solution onto a mesh while Asst Prof Tan looks on

Air pollution poses serious health threats. Even limited exposure to air pollutants, such as those found in transboundary haze, can trigger respiratory symptoms and aggravate existing heart or lung conditions. Healthy persons are not spared and may suffer from irritation of the eyes, nose and throat.

Asst Prof Tan said that most of the current nanofibres used in air filters are energy intensive to produce and require specialised equipment. "Our team has developed a simple, quick and cost-effective way of producing high-quality air filters that effectively remove harmful particles and further improves indoor air quality by enhancing air ventilation and reducing harmful UV rays," he said. He added that it may be possible in the future for anyone to buy the nanofibre solution and create DIY (do-it-yourself) air filters at home.

The researchers’ novel air filter offers a quality factor of about two times higher than commercial respirators. It can filter up to 90 per cent of hazardous particles that are less than 2.5 microns in size — also known as PM2.5 particles and associated with serious health threats. It also achieves an air flow that is 2.5 times better than these respirators, allowing better breathability.

Our team has developed a simple, quick and cost-effective way of producing high-quality air filters that effectively remove harmful particles and further improves indoor air quality by enhancing air ventilation and reducing harmful UV rays.

Describing one of the differences between the team’s invention and currently available respirators, Asst Prof Tan said that high-efficiency air filters often require multiple layers of microfibres or nanofibres, thus limiting their transparency and as such, are not suitable for incorporation in doors and windows. “The see-through air filter developed using our approach has promising applications in terms of improving indoor air quality, and could be especially useful for countries experiencing haze or with high pollution levels. While increasing filtration efficiency will lead to a trade-off in air flow, the overall performance of our air filter is still better than commercial respirators,” he explained.

The NUS research team has filed a patent for their invention, and targets to include further functionalities, such as anti-bacterial properties, into the air filter. They plan to work with industry partners to commercialise this technology as well.

See press release and media coverage.