A team of Stanford University Engineers are working on creating more effective face shields by borrowing a leaf from animal noses and snorkeling gear. They believe that the resultant PPE would serve frontline workers a lot better than what they are using now.
Stanford Bioengineer Manu Prakash was in quarantine after flying home to California from France when he looked at his gear for snorkeling and scuba diving and thought that they might just have the solution for two of the difficulties of the Covid-19 pandemic.
He realized that the collapse in the global supply chain for N95 masks had created a shortage of personal protective equipment in many hospitals. Further, “the masks that are out there, that we put in the hands of our frontline workers, are not that good,” according to Paraksh. “They’re often ill-fitting and uncomfortable, and if they don’t fit, they don’t protect.”
Prakash’s big idea was to take full-face snorkel masks and repurpose them to address the urgent need for personal protective equipment by fitting them with 3D-printed filter-holders.
His idea attracted the attention of partners around the world who collaborated in the design and testing of the adapted snorkel masks in Prakash’s own laboratory as well as other locations. The device is both a mask and shield.
Laurel Kroo is a mechanical engineer at Prakash’s lab who presented the device dubbed ‘pneumask’ to the American Physical Society’s Division of Fluid Dynamics at their annual meeting.
Researchers participating in the collaborative project have already published a set of decontamination protocols for the device that allow it to be reused. They also conducted clinical tests which suggest that it is comfortable enough to last an eight-hour shift.
“From a fluid-dynamics perspective, a mask is a hydrodynamic device,” Prakash clarified. “A lot is happening when you breathe in and breathe out. You have to have the right kind of filters. You have to think about rebreathing, and comfort.”
Not satisfied with the ‘pneumask’ Prakash’s lab is also working on other developments related to Covid-19. The lab was part of the 1000×1000 project launch repurpose candy floss machines into N95-grade mask material.
Candy floss machines melt sugar and spin the liquid into fine threads. The repurposed candy machines spun out nanofibers instead which are capable of trapping tiny particles.
They also participated in the development of a low-cost ICU ventilator called ‘Pufferfish.’
Elsewhere, Cornell University’s Sunghwan Jung observed the nasal structures of different animals and drew design lessons from them to create superior masks. Jung studies animal from a fluid dynamics perspective and works with researchers Saikat Basu and Leonardo Chamorro of South Dakota State University and the University of Illinois Urbana.
“Animals like dogs, opossums, and pigs are renowned for their super-sensitive sniffers,” Jung said. “They have a very complicated nasal structure, and we tried to mimic that structure in our filters.”
Jung describes the human nose as “fairly straightforward and vacuous” compared to dogs and pigs whose nasal cavities are more twisted and indirect which gives them their keener sense of smell. “Fluid mechanics tells us that if you have such a tortuous air pathway, you have more chances to capture more particles,” said Jung.
The researchers have created a mask filter with a more convoluted structure like the one witnessed in the animals that Jung studied. Tests have revealed that the masks they created are capable of filtering out micron-sized particles and it’s low-pressure drop makes breathing much easier.
According to Jung, the masks are still in testing and are not approved nor have they been used in hospitals.