Compact ceramic thermal cyclers for accelerated Covid-19 lab testing
The Corona pandemic has greatly increased worldwide interest in rapid yet reliable virus testing. The Fraunhofer Institute for Ceramic Technologies and Systems IKTS has now developed innovative “μPCR” laboratory modules to significantly accelerate the polymerase chain reaction (PCR) for such tests. Rapid temperature changes are required for the samples, which are made possible by a combination of ceramic 3D printing and applied electronics.
“With this solution, we want to contribute to further accelerating the PCR method, which is important for the health of the population well beyond the pandemic, and to making it even more accessible,” emphasizes IKTS director Prof. Alexander Michaelis.
Background: When a higher degree of accuracy is required than offered by commercially available rapid tests, laboratories use PCR technology to amplify and enrich the genetic material of the pathogen from nasal and pharyngeal mucus samples. In the next step, even the smallest amounts of corona viruses can be easily and conclusively detected. However, in order for the enriching chain reaction to first produce ever new copies of the genetic material, the samples undergo a kind of alternating temperature bath: The laboratory equipment must repeatedly heat the reaction vessels up to 96 degrees Celsius and then cool them back down to 55 degrees or less. These processes have to be repeated about 30 times in a precisely specified regime. Depending on the test variant, this takes around four to six hours.
3D printing technology combined with heating electronics
A team of IKTS scientists led by electrical engineer Dr. Lars Rebenklau and 3D printing expert Dr. Uwe Scheithauer, however, has now developed a promising, faster alternative. To fabricate their μPCR modules, they use additive manufacturing processes. A ceramic sleeve with integrated cooling channels is first realized on industrial 3D printers. “Using our additive manufacturing, even these complex shapes are no longer a problem, which would be impossible or very time-consuming and expensive to produce using conventional methods,” said Uwe Scheithauer. The researchers then fire the “green body” created in this way at over 1000 degrees Celsius to form a solid and very durable ceramic. They then print metallic spiral patterns on this base body, which later serve as radiators, and fire them at 850 degrees. Electrical connections and coolant hoses ultimately complete the compact μPCR modules.
These units are currently about 15 millimeters in diameter and about 45 millimeters long. They are both mini-ovens and mini-refrigerators: within a few seconds, the imprinted heating electrics bring the inserted sample vessels to the desired temperatures. Gaseous nitrogen flowing through the integrated 3D cooling channels cools the samples down again just as quickly. The individual modules can also be coupled to form larger matrix assemblies for analyzing many samples at once. According to the IKTS scientists, if the μPCR systems are consequently developed further and made production-ready, PCR analyses could be significantly accelerated in the future.
Wide range of applications ahead
“The combination of additive manufacturing, thick-film technology and other ceramic technologies, as well as simple construction, results in particularly durable, small and yet powerful PCR modules," explains Dr. Lars Rebenklau. In addition, automated large-scale production is possible. More powerful coolants and continued improvements to the printed electronics could further accelerate the PCR process. Work is currently underway to decrease the size of the developed modules even further in order to reduce the temperature sequences even further. These extremely powerful and fast ceramic heaters are also suitable for other medical devices, applications in process technology, and many other use scenarios – especially when high temperatures or harsh conditions prevail. IKTS is now looking for companies that would like to use these technologies to significantly expand the functionality of their own products.