Like the PCR tests established as the gold standard, the new test system is also based on amplification of the viral RNA. However, the partners use the LAMP method (loop-mediated isothermal amplification) for this purpose. Compared to PCR, LAMP is characterized by high robustness and sensitivity and can detect infections even at a low viral load. In addition, the amplification process runs at a constant temperature, which not only shortens processing time, but also significantly reduces energy requirements. With these properties, LAMP offers an attractive alternative to PCR, especially for point-of-care applications.
As part of the project, Fraunhofer EMFT scientists are responsible for the measurement sensor technology. The microvolume/miniature measurement system they have developed consists of a sensor array for running simultaneously both, quantifying the amount of nucleic acid and monitoring the melting curve analysis. To detect viral infection, a sample (e.g. pharyngeal swab) is dissolved in a buffer, primer and LAMP reaction mix are added, and the sample is heated to approximately 65 °C for 30 - 45 min. A change in the sensor signal indicates a positive test result. The signal is already digitally recorded by the biosensors used during the measurement. Among other things, the researchers use a pH transducer on which the LAMP reaction takes place. Just like the other biosensors used, the transducer is developed and manufactured at the Fraunhofer EMFT. To increase validity, the amplificates are subjected to a melting curve analysis. False positive results can thus be identified. In conventional methods, special fluorescent dyes and correspondingly expensive laboratory equipment are used for quantification and melting curve analysis. By using the biosensors, both costs and space requirements for virus diagnosis can be saved.