A new machine detects viruses in less than an hour – directly at the doctor’s office

The COVID-19 pandemic clarified how vulnerable the healthcare system is when rapid and accurate diagnostic tools that can distinguish between viruses are lacking.

Millions of people experienced the same uncertainty: was their cough the beginning of COVID-19 or just an ordinary case of influenza?

At the start of the pandemic, it therefore also took several days to get an answer.

Then came the infamous home tests, which could at least tell you whether you were infected with SARS-CoV-2 or not.

However, these home tests could not determine whether people were infected with another virus – and, if so, which one.

Determining which virus was actually causing the infection still required a time-consuming laboratory process, which both delayed treatment and further strained the healthcare system.

However, new research indicates that this may not be the case in the future.

Researchers have developed a machine that could potentially change how doctors diagnose respiratory infections – by providing an accurate answer in less than an hour.

Doctors can then start the relevant treatment before the patient has even left the consultation.

“The symptoms of infectious diseases can be very similar across pathogens, which makes it impossible for a general practitioner to know whether a patient has, for example, COVID-19 or influenza A or B. With this work, we wanted to give doctors a tool that can both improve everyday diagnostics and strengthen preparedness for future virus outbreaks,” says Group Leader and Professor Yi Sun from the Department of Health Technology of the Technical University of Denmark.

The research has been published in ACS Sensors. The work was carried out in close collaboration with Associate Professor Sanshui Xiao from the Department of Electrical and Photonics Engineering, Technical University of Denmark, and Professor Jan Gorodkin fromCenter for non-coding RNA in Technology and Health, Department of Veterinary and Animal Sciences, University of Copenhagen.

How the machine works – and why it is a breakthrough

The device developed by the researchers is essentially a machine for both amplifying and analysing DNA/RNA from viruses.

Laboratories use solid-phase polymerase chain reaction (SP-PCR). The virus’s DNA/RNA is bound to a small surface on which the copying takes place directly. The method works like a kind of photocopier: it takes the few viral fragments in the sample and produces thousands of copies so that they can be measured and recognised.

Each virus has its own genetic fingerprint, and the chip contains small fields, each of which searches for a specific pattern. When the copying is complete, the fields that light up show exactly which virus is present.

This technology has never previously been available at the point of care – that is, directly at the doctor’s surgery.

That is precisely what the machine developed by the researchers can now do.

“The aim is to make it easier for doctors to determine what is wrong with their patients. Today, doctors have to send a sample – for example a saliva sample – to a laboratory, which only provides an answer after a few days. Our aim is to make it easier for doctors to get a quick answer about what their patients have,” explains Yi Sun.

One chip, up to 30 viruses: multiplex diagnostics in 45 minutes

In practice, the doctor places a drop of the sample on a small disposable chip – like a thin plastic plate – and inserts it into the machine.

The sample might, for instance, be a saliva sample, and it does not need to contain more than around 10 copies of the virus’s DNA/RNA. This is a very low detection limit and is comparable to what hospital-grade laboratory equipment can achieve.

The machine amplifies the DNA/RNA and tests it against many genetic markers in the panel. This is essentially the equivalent of running up to 30 PCR tests at once – but on a single chip.

Inside the chip sits a nanostructured metasurface that amplifies the light signals from the genetic markers. It makes even very weak signals measurable, enabling the machine to identify viruses with high sensitivity.

In this way, it can determine whether the patient has influenza, COVID-19 or something else.

“So far, we have shown that our machine can determine whether a person is infected with 10 types of viruses, but that number can be increased to 30. This means that doctors can determine which virus a patient has – without sending the sample to a laboratory,” says Yi Sun.

What this means in practice for doctors, patients – and the healthcare system

Yi Sun imagines a future in which rapid virus diagnostics become a natural part of general practice, strengthening treatment, contact tracing and preparedness from the moment the patient walks through the door. The doctor would take a saliva sample and place it in a device for analysis that is not much larger than a desktop printer.

The patient then waits in the waiting room while the machine runs the test – a bit like a coffee machine that simply gets on with the job by itself.

When the result is ready, the patient can be told what they are infected with, and the doctor can then begin the appropriate treatment or give a pharmaceutical recommendation.

The machine, which the researchers are now working to put into mass production, will cost around DKK 50,000, and the individual chips used for each test cost a few hundred kroner.

This is not especially expensive, but it is not exactly cheap either.

For that reason, Yi Sun expects that doctors will only use the device when a somewhat faster response is needed.

“Compared with a laboratory result, the answer comes quickly and simply. If more advanced analyses are required, or if the case is not urgent, the doctor will still send the sample to a standard laboratory, where more in-depth testing can be carried out. But if you need an answer straight away, for example during a new pandemic, then it may well be worth paying a little extra for a rapid result,” she says.