The aluminium test cartridge. (Image: Michele Gregorini/ETH Zurich)
Instead of the conventional method of mixing the PCR reagents in a plastic tube, diaxxo’s solution works by simply pipetting a droplet of the patient’s sample straight into one of the wells in the aluminium cartridge. Since metal conducts heat much better than plastic, the new device can heat and cool the reagents considerably faster than conventional devices.
This is important, because replicating the pathogen’s genetic material relies on reaction cycles consisting of multiple steps that are carried out at different temperatures ranging from 55 to 95 degrees Celsius. Performing one of these cycles takes just under 20 seconds in the new device, as opposed to two and a half minutes in a conventional device. This reduces the time required for a 45-cycle PCR test from over two hours to just under 20 minutes, which is similar to the time it takes to perform a rapid antigen test.
The new device also eliminates the need to painstakingly pipette multiple PCR reagents into a sample container. Instead, diaxxo’s solution is to deliver the reagents as part of the package – freeze-dried and deposited in the bottom of each well. This also has the advantage of enabling test kits for different pathogens to be stored at room temperature for up to six months.
Pandemic gives the project a boost
Gregorini and Bechtold encountered plenty of challenges when it came to developing a reliable method. Bechtold spent a long time perfecting a drying process for the reagents that ensures they mix properly with the sample when the time comes. “That was one of the toughest tasks of all,” he says, recalling how difficult it was to get the reagents attached firmly enough in the wells for the cartridges to be transported safely.
But the biggest turning point of all came in spring 2020 with the emergence of the coronavirus pandemic. “All of a sudden, there was this huge demand for the medical device at the heart of our research project,” Gregorini says. Even before the virus had fully arrived in Switzerland, the engineers began developing a cartridge to detect SARS-Cov-2 – their first ever diagnostic test.
From there, things just snowballed. The two researchers obtained their first grant from the Swiss National Science Foundation’s “Bridge” programme, swiftly followed by coronavirus funding from various other sources. In September 2020, Gregorini and Bechtold were accepted into the ETH Pioneer Fellowship programme; in October, they founded their company, diaxxo.
From developers to managers
Today, diaxxo employs 12 people as part of a growing team of hardware and software specialists, biotechnologists and electrical engineers. Together, they are steadily improving the PCR device to make it ready for the market.
At the same time, the focus of the two founders has shifted away from product development as they gradually slip into more of a managerial role. They now spend most of their time answering questions from the team, preparing presentations for potential backers and communicating with project partners by email. It’s not until the early evening, when most of his colleagues have already gone home, that Gregorini finally finds time to check out how things are progressing in their workshop at ETH.
Field study in Zanzibar provides important inputs
Meanwhile, the list of potential customers just keeps on growing. New enquiries are arriving by the day – including interest from a major cruise line. But with the device currently still pending approval as a medical device, the company founders are not permitted to sell their products to private customers and must instead rely on research collaborations. These joint projects offer the perfect channel for improving the device’s suitability for everyday use.
diaxxo’s project with the Swiss Tropical and Public Health Institute (Swiss TPH) is the biggest collaboration the start-up has embarked on so far. It involves a field study in Zanzibar, where diaxxo devices are currently being used to test schoolchildren across the country for schistosomiasis, a disease caused by parasitic worms.
Swiss TPH’s partners are particularly enthusiastic about the new PCR device because it allows them to carry out on-site testing in schools. Gregorini and Bechtold are available around the clock to support researchers in using the device, and they have already helped improvise everything from software updates to local repair manuals.
