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.
FREEDOM OF NAVIGATION: The UK would continue to reinforce ties with Taiwan ‘in a wide range of areas’ as a part of a ‘strong unofficial relationship,’ a paper said The UK plans to conduct more freedom of navigation operations in the Taiwan Strait and the South China Sea, British Secretary of State for Foreign, Commonwealth and Development Affairs David Lammy told the British House of Commons on Tuesday. British Member of Parliament Desmond Swayne said that the Royal Navy’s HMS Spey had passed through the Taiwan Strait “in pursuit of vital international freedom of navigation in the South China Sea.” Swayne asked Lammy whether he agreed that it was “proper and lawful” to do so, and if the UK would continue to carry out similar operations. Lammy replied “yes” to both questions. The
‘OF COURSE A COUNTRY’: The president outlined that Taiwan has all the necessary features of a nation, including citizens, land, government and sovereignty President William Lai (賴清德) discussed the meaning of “nation” during a speech in New Taipei City last night, emphasizing that Taiwan is a country as he condemned China’s misinterpretation of UN Resolution 2758. The speech was the first in a series of 10 that Lai is scheduled to give across Taiwan. It is the responsibility of Taiwanese citizens to stand united to defend their national sovereignty, democracy, liberty, way of life and the future of the next generation, Lai said. This is the most important legacy the people of this era could pass on to future generations, he said. Lai went on to discuss
MISSION: The Indo-Pacific region is ‘the priority theater,’ where the task of deterrence extends across the entire region, including Taiwan, the US Pacific Fleet commander said The US Navy’s “mission of deterrence” in the Indo-Pacific theater applies to Taiwan, Pacific Fleet Commander Admiral Stephen Koehler told the South China Sea Conference on Tuesday. The conference, organized by the Center for Strategic and International Studies (CSIS), is an international platform for senior officials and experts from countries with security interests in the region. “The Pacific Fleet’s mission is to deter aggression across the Western Pacific, together with our allies and partners, and to prevail in combat if necessary, Koehler said in the event’s keynote speech. “That mission of deterrence applies regionwide — including the South China Sea and Taiwan,” he
UNPRECEDENTED: In addition to the approved recall motions, cases such as Ma Wen-chun’s in Nantou are still under review, while others lack enough signatures The Central Election Commission (CEC) announced yesterday that a recall vote would take place on July 26, after it approved the first batch of recall motions targeting 24 Chinese Nationalist Party (KMT) lawmakers and Hsinchu Mayor Ann Kao (高虹安). Taiwan is in the midst of an unprecedented wave of mass recall campaigns, following a civil society push that echoed a call made by Democratic Progressive Party (DPP) caucus whip Ker Chien-ming (柯建銘) in January to initiate signature drives aimed at unseating KMT legislators. Under the Civil Servants Election and Recall Act (公職人員選舉罷免法), Taiwanese can initiate a recall of district-elected lawmakers by collecting
RSS