PCR tests are the right choice for detecting infection-causing viruses such as SARS-CoV‑2. Today, no one has to wait long for the results. Qiagen, for example, has developed the compact QIAstat-Dx analyzer, which, in combination with the appropriate test cartridges, enables real-time PCR for the rapid detection of pathogen nucleic acids in human biological samples. More than 20 pathogens, including Covid-19, can be detected in a single run within just 60 minutes. The small test cartridges (Fig. 1) contain all the necessary laboratory equipment in miniature format with all solid and liquid reagents.
At the same time, they are uncomplicated to handle: The sample is taken from the patient and inserted into the cartridge. Only a few steps are required to insert it into the analyzer. The test can start after just one minute. To prevent the necessary liquids from leaking, the cartridges must be absolutely leakproof and, as a medical product, must meet high quality requirements. At the same time, production costs should remain as low as possible, since each cartridge can only be used once. For Qiagen, ultrasonic welding systems are therefore the method of choice for joining plastic parts inside the cartridge.
Large quantities with consistent quality
Today, welding with ultrasound is considered the fastest and also the most cost-effective and reliable method of joining and assembling plastic parts. Key advantages are that no adhesives, fasteners or solvents are used; this also makes the process very environmentally friendly and efficient. At the Barcelona site, where Qiagen manufactures the test cartridges, two ultrasonic welding systems from Telsonic are now in operation (Fig. 2). One was already in use before the pandemic; the second has now been added due to increased demand. Both are housed in soundproof booths that provide effective shielding for the employees. Today, up to 2,000 cylindrical plastic parts are fixed inside the test cartridges with secure and absolutely tight weld seams every day.
The robust and durable ultrasonic welding systems of type USP750 have already proven themselves many times over in large-scale production, not only in medical technology but also in the automotive industry, for example. Low maintenance, high reliability and long service life are the prerequisites for this. Thanks to the high flexibility during changeover, the systems are also ideally suited for applications with small production runs. In addition, end-to-end process control can be easily implemented. Welding results are monitored in quality windows and automatically evaluated graphically and statistically. This guarantees that the test cartridges for the fast PCR analyzer can be manufactured in large quantities with consistent quality.
