Wearing a mask can help prevent the spread of viruses such as SARS-CoV-2, but the effectiveness of a mask depends on how well it fits.
Currently, there is no simple way to measure the fit of a mask, but a new sensor developed at MIT could make ensuring a good fit much easier. The sensor, which measures the physical contact between the mask and the wearer’s face, can be applied to any type of mask.
Using this sensor, researchers analyzed the fit of surgical masks on male and female subjects and found that, overall, the masks fit women’s faces much worse than women’s faces. men.
“What we realized by analyzing our data collected from individuals in the study is that the masks we use in daily life don’t fit the participants very well,” says Canan Dagdeviren, professor of career development. LG in Media Arts and Sciences at MIT. and the corresponding author of the study.
The researchers hope their sensor will help people find masks that fit them better, and that designers can use it to create masks that fit a wider variety of face shapes and sizes. The sensor can also be used to monitor vital signs such as breathing rate and temperature, as well as environmental conditions such as humidity.
The study is a collaboration between the Dagdeviren laboratory; Siqi Zheng, STL Champion Professor of Urban and Real Estate Sustainability in the Department of Urban Studies and Planning; and Tolga Durak, general manager of MIT’s environmental, health, and safety programs. Jin-Hoon Kim, a postdoctoral fellow at MIT, is the lead author of the paper, which appears today in Natural electronics.
Quality of fit
Researchers began working on this project before mask-wearing became common during the Covid-19 pandemic. Their original intention was to use sensors embedded in masks to measure the effectiveness of mask-wearing in areas with high levels of air pollution. However, once the pandemic hit, they realized that such a sensor could have more widespread applications.
With so many different types of masks available during the pandemic, researchers thought this type of sensor could be useful in helping individuals find the mask that works best for them. Currently, the only way to measure mask fit is with a machine called a mask fit tester, which assesses mask fit by comparing concentrations of air particles inside and outside. exterior of the face mask. However, this type of machine is only available in specialized establishments such as hospitals, which use them to assess the fit of masks for healthcare workers.
The MIT team wanted to create a more user-friendly wearable device to measure mask fit. Dagdeviren’s lab, the Conformable Decoders Group, specializes in the development of flexible and stretchable electronics that can be worn on the skin or incorporated into textiles to detect signals from the body.
“In this project, we wanted to simultaneously monitor biological and environmental conditions, such as respiratory pattern, skin temperature, human activities, temperature and humidity inside the face mask, and mask position. , including whether people are wearing it correctly or not,” Kim says. “We also wanted to check the quality of the fit.”
To integrate their sensors into the face masks, the researchers created a device they call a conformable multimodal sensor face mask (cMaSK). Sensors that measure a variety of parameters are built into a flexible polymer frame that can be reversibly attached inside any mask, around the edges.
To measure fit, the cMaSK has 17 sensors around the edge of the mask that measure capacitance, which can be used to determine if the mask is touching the skin at each of these locations.
The cMaSK interface also has sensors that measure temperature, humidity, and atmospheric pressure, which can detect activities such as talking and coughing. An accelerometer inside the device can reveal if the wearer is moving. All sensors are embedded in a biocompatible polymer called polyimide, which is used in medical implants such as stents.
The researchers tested the cMaSK interface in a group of five men and five women. All subjects wore surgical masks, and researchers monitored sensor readings while participants performed various activities, such as talking, walking, and running. They also tested the sensors under various temperature conditions.
Using data obtained from the capacitive sensors, the researchers created a machine-learning algorithm to calculate the mask’s goodness-of-fit for each subject in the study. These measurements revealed that mask fit was significantly worse for women than for men, due to gender differences in face shape and size. However, the fit for women could be slightly improved by wearing smaller surgical masks. The researchers also found that the fit quality of the mask was poor for one of the male subjects with a beard, which created gaps between the mask and the skin.
To verify their results, the researchers also collaborated with MIT’s Office of Environment, Health, and Safety on fit design and evaluation, and found that the fit results for each study participant were very similar to what they had found using cMaSK.
Custom fit
The researchers hope their findings will encourage mask makers to design masks that fit a variety of face shapes and sizes, especially women’s faces. The Dagdeviren lab plans to work on mass production and large-scale deployment of the cMaSK interface.
“We hope to think about ways to design masks and find the best fit for individuals,” says Dagdeviren. “We have different shoe sizes, and you can even customize your shoes. So why can’t you customize and design your mask, for your own health and for the good of society?”
The researchers also hope to return to their original idea of studying the effects of air pollution on people who work outdoors.
“Our technology can really help quantify the social costs of these environmental risks, and also measure the benefits of any kind of policy intervention,” Zheng said.
The research was funded by the MIT Media Lab Consortium, the 3M Non-Tenured Faculty Award, and the MIT International Science and Technology Initiative (MISTI) Global Fund.
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