Clip-on gadget detects if Covid-19 particles are in the air around you

A tiny device that can clip on to clothing and detect the wearer’s exposure to Covid has been developed by scientists.

Scientists previously used active air sampling devices to detect airborne Covid-19 indoors, but these monitors are usually large, expensive, not portable and need electricity.

Krystal Pollitt, assistant professor of epidemiology and chemical engineering along with her colleagues at Yale School of Engineering in Connecticut in the US, wanted to develop a new device.

They came up with a small, lightweight, cheap and wearable device that does not need a power source so they could better understand personal exposures to the virus.

Researchers developed the passive air sampler – known as the Fresh Air Clip – that continually adsorbs virus-laden aerosols on a polydimethylsiloxane (PDMS) surface.

The authors of the study wrote: “Exhaled respiratory droplets and aerosols can carry infectious viruses and are an important mode of transmission for Covid-19.

‘Recent studies have been successful in detecting airborne Covid-19 RNA in indoor settings using active sampling methods.

‘The cost, size, and maintenance of these samplers, however, limit their long-term monitoring ability in high-risk transmission areas.

‘As an alternative, passive samplers can be small, lightweight, and inexpensive and do not require electrical power or maintenance for continual operation.

‘Integration of passive samplers into wearable designs can be used to better understand personal exposure to the respiratory virus.

‘This study evaluated the use of a polydimethylsiloxane (PDMS)-based passive sampler to assess personal exposure to aerosol and droplet Covid-19.’

The team tested the air sampler in a rotating drum in which they generated aerosols containing a surrogate virus – a bacteriophage with similar properties to Covid-19.

They detected the virus on the PDMS sampler using the polymerase chain reaction (PCR), showing that the device could be used to reliably estimate airborne virus concentrations.

Then the researchers distributed Fresh Air Clips to 62 volunteers, who wore the monitors for five days.

PCR analysis of the clips detected Covid RNA in five of the clips. Four were worn by restaurant servers and one by a homeless shelter worker.

The highest viral loads – of more than 100 RNA copies per clip – were detected in two badges from restaurant staff, scientists said.

The study authors added: ‘The rate of uptake of virus-laden aerosol on PDMS was determined in lab-based rotating drum experiments to estimate time-weighted averaged airborne viral concentrations from passive sampler viral loading.

‘The passive sampler was then embedded in a wearable clip design and distributed to community members across Connecticut to survey personal Covid-19 exposure.

‘The virus was detected on clips worn by five of the 62 participants – a rate of eight per cent – with personal exposure ranging from four to 112 copies of Covid-19 RNA/m3, predominantly in indoor restaurant settings.’

‘Our findings demonstrate that PDMS based passive samplers may serve as a useful exposure assessment tool for airborne viral exposure in real-world high-risk settings and provide avenues for early detection of potential cases and guidance on site-specific infection control protocols that pre-empt community transmission.’

Although the Fresh Air Clip has not yet been made to be sold to the public, these results show it could serve as a rough screening tool for working out personal exposure to Covid, the experts said.

It could also help find high-risk areas indoors, according to the researchers.

The findings were published in ACS’ Environmental Science and Technology Letters with funding from the National Science Foundation and the Rothberg Fund.