Decapping covid-19 test tube
A flexible de-capping solution for different sizes of test tube caps used for SARS-CoV-2 diagnostics.

This is a collaboration between Karolinska Institute and KTH Prototype Center

Covid-19 test tube decapper is free-licensed/ opensource under CC BY 4.0  

Opening many test tubes is both a time-consuming and laborious task. Unfortunately, the procedure of removing the cap (de-capping) from the tube must often be carried out manually as there are no or few automatic solutions capable of handling a large variety of test tubes.

Benjamin Heller Sahlgren have been involved in starting the COVID-19 diagnostics pipeline at the Karolinska Institute, where he and a fellow college has been responsible for starting and administrating the sample reception unit. Considering that the sample reception laboratory is the first step in the diagnostics pipeline and thus directly handles the incoming samples, the unit quickly identified the need for a automatic solution capable of removing the burden of the manual de-capping step.
Since the incoming test tubes differed both in size and diameter, an automatic de-capping solution capable of handling a large variety of tubes was required. However, such a machine was not available on the market and thus the potential of building a novel de-capping machine became the only feasible solution to the problem. KTH Prototype Center was contacted, and the situation and the requirements were explained to Lars Hässler who immediately started the development of a novel de-capping solution. The result was a machine flexible enough to remove almost all kinds of caps that differ not only in size and diameter but also design.

Machine designe
Lars Hässler

Covid-19 testing
Benjamin Heller Sahlgren:

In the BOM list, you can find everything about materials and manufacturing for a test tube opening machine.
Photo / film Lars Hässler and Benjamin Heller Sahlgren

KTH wrote about the project: see here

To receive CAD drawings and Bom list send an e-mail to


Insert the test tube between the two non-drive rollers

Press down the foot pedal, the arm with the motor and the drive roller move towards the test tube and the engine starts.

Remove the test tube without swab loosening and place it in the test tube rack.

Release the foot pedal and the cork and swab falling into the garbage container and the machine goes to sleep / start position