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.
A Chinese freighter that allegedly snapped an undersea cable linking Taiwan proper to Penghu County is suspected of being owned by a Chinese state-run company and had docked at the ports of Kaohsiung and Keelung for three months using different names. On Tuesday last week, the Togo-flagged freighter Hong Tai 58 (宏泰58號) and its Chinese crew were detained after the Taipei-Penghu No. 3 submarine cable was severed. When the Coast Guard Administration (CGA) first attempted to detain the ship on grounds of possible sabotage, its crew said the ship’s name was Hong Tai 168, although the Automatic Identification System (AIS)
CHANGE OF MIND: The Chinese crew at first showed a willingness to cooperate, but later regretted that when the ship arrived at the port and refused to enter Togolese Republic-registered Chinese freighter Hong Tai (宏泰號) and its crew have been detained on suspicion of deliberately damaging a submarine cable connecting Taiwan proper and Penghu County, the Coast Guard Administration said in a statement yesterday. The case would be subject to a “national security-level investigation” by the Tainan District Prosecutors’ Office, it added. The administration said that it had been monitoring the ship since 7:10pm on Saturday when it appeared to be loitering in waters about 6 nautical miles (11km) northwest of Tainan’s Chiang Chun Fishing Port, adding that the ship’s location was about 0.5 nautical miles north of the No.
An Akizuki-class destroyer last month made the first-ever solo transit of a Japan Maritime Self-Defense Force ship through the Taiwan Strait, Japanese government officials with knowledge of the matter said yesterday. The JS Akizuki carried out a north-to-south transit through the Taiwan Strait on Feb. 5 as it sailed to the South China Sea to participate in a joint exercise with US, Australian and Philippine forces that day. The Japanese destroyer JS Sazanami in September last year made the Japan Maritime Self-Defense Force’s first-ever transit through the Taiwan Strait, but it was joined by vessels from New Zealand and Australia,
COORDINATION, ASSURANCE: Separately, representatives reintroduced a bill that asks the state department to review guidelines on how the US engages with Taiwan US senators on Tuesday introduced the Taiwan travel and tourism coordination act, which they said would bolster bilateral travel and cooperation. The bill, proposed by US senators Marsha Blackburn and Brian Schatz, seeks to establish “robust security screenings for those traveling to the US from Asia, open new markets for American industry, and strengthen the economic partnership between the US and Taiwan,” they said in a statement. “Travel and tourism play a crucial role in a nation’s economic security,” but Taiwan faces “pressure and coercion from the Chinese Communist Party [CCP]” in this sector, the statement said. As Taiwan is a “vital trading
RSS