Engineering news
Engineers at the Massachusetts Institute of Technology (MIT) and Harvard University developed a mask capable of doing just that, thanks to a tiny disposable sensor.
The sensor can diagnose the wearer with Covid-19 in about 90 minutes. The devices are based on freeze-dried ‘cellular machinery’ that the research team previously developed for use in paper diagnostics for viruses such as Ebola and Zika.
The team finished work on the wearable sensors in early 2020, but adapted them for the virus that causes Covid-19 as the pandemic took hold. The sensors are designed so they can be activated by the wearer when they are ready to perform the test, and the results are only displayed on the inside of the mask to maintain user privacy.
James Collins, senior author of the new study, previously showed that proteins and nucleic acids needed to create synthetic gene networks that react to specific target molecules could be embedded into paper in 2014. He used this approach to create paper diagnostics for the Ebola and Zika viruses.
In 2017 he developed another cell-free sensor system, known as Sherlock, which is based on Crispr enzymes and allows highly sensitive detection of nucleic acids. These cell-free circuit components are freeze-dried and remain stable for many months, until they are rehydrated. When activated by water, they can interact with their target molecule – which can be any RNA or DNA sequence, as well as other types of molecules – and produce a signal such as a change in colour.
To make wearable sensors, the researchers embedded their freeze-dried components into a small section of synthetic fabric, surrounded by a ring of silicone elastomer. The team embedded about 30 of them into a jacket to demonstrate the technology, showing that a small splash of liquid containing viral particles could hydrate the freeze-dried cell components and activate the sensor.
The sensors can be designed to produce different types of signals, including colour changes that can be seen with the naked eye, or fluorescent or luminescent signals that can be revealed with a handheld spectrometer. The researchers also designed a wearable spectrometer that could be integrated into the fabric, where it can read the results and wirelessly transmit them to a mobile device.
To produce their diagnostic face mask, the researchers embedded freeze-dried Sherlock sensors into the inside of a paper mask, to detect viral particles on the breath. The mask also includes a small reservoir of water, which can be released to hydrate the freeze-dried components when the wearer is ready to perform the test. The sensor then analyses accumulated breath droplets on the inside of the mask and produces a result within 90 minutes.
“This test is as sensitive as the gold standard, highly sensitive PCR tests, but it's as fast as the antigen tests that are used for quick analysis of Covid-19,” said lead author Peter Nguyen from Harvard.
The researchers can also swap in sensors for other pathogens, including influenza, Ebola, and Zika, or sensors they have developed to detect organophosphate nerve agents.
The team has filed for a patent on the technology, and they are now hoping to work with a company to further develop the sensors. The face mask is most likely the first application that could be made available, Collins said.
Luis Soenksen from MIT was also a lead author of the paper, which appeared in Nature Biotechnology.
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