Meet CoroNaspresso, the COVID-19 Test in a Coffee Capsule

Testing for COVID-19 with a coffee capsule and a pan? This is the original idea of a scientist from the University of Wageningen in the Netherlands. Hoping to reduce the cost of COVID-19 detection tests currently offered on the market, he used an empty aluminum coffee capsule and turned it into a small chemical reactor. What makes this project particularly interesting to us is that he 3D printed a plastic holder that can hold 4 tubes to perform the tests. Called CoroNaspresso, this new screening method could increase the number of tests performed each day while facilitating the process. It would cost about 24¢ (0.20€).

Vittorio Saggiomo is an Italian chemist in the Bionanotechnology group at Wageningen University in the Netherlands. Last March, he tackled the problem of centralized PCR testing, explaining that the means of screening should nowadays be easier to do as well as cheap in order to produce tests in large quantities. To do this, he relied on loop-mediated isothermal amplification (LAMP), a low-cost technique for detecting certain diseases. It can be performed at a constant temperature (65°C) and no laboratory equipment is required. Specifically, the saliva sample is heated and, using pH indicators, changes color if Sars-CoV-2 is present. Vittorio Saggiomo explains, “The color change is very striking: negative samples are pink and positive ones are yellow.” But how do you maintain a constant temperature while remaining accessible?

Positive results are yellow (photo credits: Vittorio Saggiomo)

CoroNaspresso, between coffee and 3D printing

This is where the coffee capsule comes in: an everyday product, it served as a container that could be dipped into a pot of boiling water. The capsule is filled with a phase change material, specifically RT64HC, a wax that melts between 63 and 65°C (145.4-149°F). It is an inexpensive material (about €13 or $15 per kilo) whose melting/solidification process takes about 25 minutes (5 grams for 1 liter of water). A 3D-printed holder holds the 4 tubes of 200μl containing the saliva samples. Few details are given as to the 3D printing itself, we just know that PLA was used. The part seems uncomplicated and accessible to anyone with an FDM 3D printer at home. The use of additive manufacturing is most probably in part a reflection of the logic behind the test that puts an emphasis on ease of use and execution but also for mass production: as the part is quite small and not very complex, one could easily print dozens of them in one go.