A University of Connecticut mechanical engineering lab has filed a patent for the first biodegradable and reusable face mask, Thinh Le, mechanical engineering Ph.D student, said.
Le is a member of UConn assistant professor of mechanical engineering Thanh Nguyen’s research group, and the two are listed as inventors on the patent along with Eli Curry, a former lab member and current postdoc at John Hopkins University and Tra Nguyen, Ph.D student.
Le said their masks are made out of FDA-approved biodegradable material that can be disinfected using a machine called an autoclave, a steam sterilizer. The masks most commonly used throughout the pandemic, the surgical and N95 masks, do not utilize this material and are not biodegradable.
“The common masks, the surgical mask and N95, are made from polypropylene, which are not degradable and not piezoelectric,” Le said. “These respirators are not reusable and usually disposed of after eight to twelve hours of use. Our mask is made from poly-L lactic acid, an FDA-approved material [used] in medical applications, which is completely safe and biodegradable.”
Le said their masks have preliminary test results of being 92% efficient.
Le said their masks are made out of FDA-approved biodegradable material that can be disinfected using a machine called an autoclave, a steam sterilizer. The masks most commonly used throughout the pandemic, the surgical and N95 masks, do not utilize this material and are not biodegradable. 
All Photos provided by Thinh Le.
“So right now, we haven’t publicly tested the mask yet, but at this moment, we have had some preliminary results so the filtering efficiency can be a valid 92%, which is higher than a surgical mask but slightly lower than a N95,” Le said.
The lab’s mask has piezoelectric electrospun nanofibers. According to UConn Today, piezoelectricity is a type of pressure-induced electricity that converts mechanical force into an electric charge.
Le said the traditional masks only use electrostatic force. By combining electrostatic force and piezoelectricity, the lab’s masks have a higher filtration efficiency.
“In terms of working principle, the common masks utilize the inherent surface charge, electrostatic force, to attract the tiny particles,” Le said. “On the other hand, our [poly-L lactic acid] nanofibers mat possesses the piezoelectricity as well as the inherent surface charge, which combinedly enhance the filtration efficiency of the material.”
In order to create the material for the mask, the group created the nanofiber mats by using the electrospinning process, Le said. According to ScienceDirect, electrospinning is a type of fiber production method that uses electric force to combine polymers into nanofibers.
“By engineering the parameters during this process, we can tune the porosity, fiber size, fiber morphology, alignments [and etc.], hence achieve favorable results,” Le said.
The research group collaborates with Dr. Jeffrey McCutcheon, UConn chemical and biomolecular engineering associate professor and Institute of Materials Science faculty member, to test filtration efficiency, Le said.
In order to test the mask’s reusability, the researchers need to test the piezoelectric performance of the nanofibers after autoclaving, Le said. The group collaborates with Dr. Osama Bilal, UConn mechanical engineering assistant professor to do so. If the piezoelectric performance remains at a similar level, the masks can be reused.
“We’ve used a vibrometer system to measure the velocity profile of the material before and after autoclaving and found there is no significant difference in the velocity profile, which implies its piezoelectric performance remains,” Le said. “Besides that, we have used scanning electron microscopy to confirm the fiber morphology doesn’t change much post-autoclave.”
Le said it could still be some time before the general public would be able to buy a biodegradable, reusable face mask. The next step in their experientimentaion is to test the filtering efficiency of their masks after autoclaving and to improve the breathability of the material to make it more comfortable to wear.
Eventually, Le said the team does want to commercialize the mask as it “could be a huge contribution to the environment and to society.”
“If people care about the environment, they should buy a biodegradable face mask,” Le said. “Also, for example, you had to buy three N95 masks and they can be used for three days. With a single biodegradable and reusable face mask, you only need one for those three days. Lets see how many materials you can save and protect the environment.”
