The inventor of the key technology used in N95 respirator and medical masks is Taiwan-born scientist Peter Tsai (蔡秉燚), the Nonwoven Fabrics Industry Association said on Facebook on Monday.
Tsai was a professor in the University of Tennessee’s material sciences and engineering department for 35 years before retiring last year, and is a world-renowned expert in nonwoven fabrics.
He invented the electrostatic charging technology used to produce the filter media of masks, including medical and N95 masks, as well as heating, ventilating and air conditioning filters, and holds 12 US patents and 20 commercial license agreements for his inventions.
Photo: Bloomberg
While Tsai might not be a household name, he recently became familiar to Taiwanese due to an article he wrote answering common questions about sterilizing and reusing N95 masks, the association said.
The “N” in the respirator name means “not resistant to oil,” and “95” means the ability to remove at least 95 percent of submicron particles, such as influenza viruses, dust, pollen, haze and smoke, the association said.
N95 respirators are made of four plies of polypropylene media: an outer veil that can resist moisture, a double-ply filtration layer and an inner layer that is in contact with the skin, it said.
The outer and inner layers — usually made of spun-bond nonwoven and thermal-bond nonwoven fabrics — have low filtration efficiency and breathing resistance, and serve primarily to contain the middle layer, it said.
The middle layer, made of meltblown nonwoven fabrics, seals any gaps through which submicron particles might be able to enter and is key to the N95 respirator’s filtration efficiency, it said.
To manufacture meltblown nonwoven fabrics, two fundamental technologies are required: melt blowing and electrostatic charging, with the former being a nonwoven process that makes a fabric composed of microfibers; and the latter being the embedding of permanent charges in a fiber to form an electret that enhances filter efficiency by electrostatic attraction, the association said.
Tsai’s research in melt blowing and electrostatic charging greatly improved the filtration efficiency of nonwoven fabrics used in masks, allowing submicron particles to be captured and stopped from traveling through the masks, it said.
Tsai found that a charged medium has 10 times the filtration efficiency of an uncharged medium, meaning that one ply of charged fabric can have the same power as 10 plies of the same uncharged fabric, and better air permeability, too, it said.
According to the article, when high-quality masks are exposed to elevated temperatures, such as 70°C, for 30 minutes, the chances that a charge will decay are extremely low, so people can repeat this sterilizing method multiple times without a noticeable loss in filtration efficiency, as long as the masks are suspended without coming into contact with or being near a metal surface, Tsai said in an article for the University of Tennessee Research Foundation that was published on March 25.
As for treating masks with bleach, the article states that charges will not degrade as long as the ingredients do not include surfactants, while hot water generally does not affect the mask’s filtration performance, as long as the inner and outer veils of the mask are not made of paper-like tissue.
The government is aiming to recruit 1,096 foreign English teachers and teaching assistants this year, the Ministry of Education said yesterday. The foreign teachers would work closely with elementary and junior-high instructors to create and teach courses, ministry official Tsai Yi-ching (蔡宜靜) said. Together, they would create an immersive language environment, helping to motivate students while enhancing the skills of local teachers, she said. The ministry has since 2021 been recruiting foreign teachers through the Taiwan Foreign English Teacher Program, which offers placement, salary, housing and other benefits to eligible foreign teachers. Two centers serving northern and southern Taiwan assist in recruiting and training
WIDE NET: Health officials said they are considering all possibilities, such as bongkrekic acid, while the city mayor said they have not ruled out the possibility of a malicious act of poisoning Two people who dined at a restaurant in Taipei’s Far Eastern Department Store Xinyi A13 last week have died, while four are in intensive care, the Taipei Department of Health said yesterday. All of the outlets of Malaysian vegetarian restaurant franchise Polam Kopitiam have been ordered to close pending an investigation after 11 people became ill due to suspected food poisoning, city officials told a news conference in Taipei. The first fatality, a 39-year-old man who ate at the restaurant on Friday last week, died of kidney failure two days later at the city’s Mackay Memorial Hospital. A 66-year-old man who dined
‘CARRIER KILLERS’: The Tuo Chiang-class corvettes’ stealth capability means they have a radar cross-section as small as the size of a fishing boat, an analyst said President Tsai Ing-wen (蔡英文) yesterday presided over a ceremony at Yilan County’s Suao Harbor (蘇澳港), where the navy took delivery of two indigenous Tuo Chiang-class corvettes. The corvettes, An Chiang (安江) and Wan Chiang (萬江), along with the introduction of the coast guard’s third and fourth 4,000-tonne cutters earlier this month, are a testament to Taiwan’s shipbuilding capability and signify the nation’s resolve to defend democracy and freedom, Tsai said. The vessels are also the last two of six Tuo Chiang-class corvettes ordered from Lungteh Shipbuilding Co (龍德造船) by the navy, Tsai said. The first Tuo Chiang-class vessel delivered was Ta Chiang (塔江)
EYE ON STRAIT: The US spending bill ‘doubles security cooperation funding for Taiwan,’ while also seeking to counter the influence of China US President Joe Biden on Saturday signed into law a US$1.2 trillion spending package that includes US$300 million in foreign military financing to Taiwan, as well as funding for Taipei-Washington cooperative projects. The US Congress early on Saturday overwhelmingly passed the Further Consolidated Appropriations Act 2024 to avoid a partial shutdown and fund the government through September for a fiscal year that began six months ago. Under the package, the Defense Appropriations Act would provide a US$27 billion increase from the previous fiscal year to fund “critical national defense efforts, including countering the PRC [People’s Republic of China],” according to a summary