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Safety and reliability are paramount in the evaluation of PCR test tubes. Femitec from Neusäß, a manufacturer for automated solutions, has developed a laboratory cell with two cooperating six-arm robots - a novelty in laboratory technology.
Tests for coronavirus (SARS-CoV-2) are performed everywhere and as a matter of course. A reliable method for detecting viruses is polymerase chain reaction (PCR); in this PCR test, known as a pathogen detection test, secretion from a swab of the nasopharynx and oral pharynx of the person tested is immersed in a plastic tube filled with buffer fluid. The sample is analyzed in a laboratory - with a repetitive handling procedure: remove the tube from the collection tray, shake it and perform the barcode identification. Now the cap of the tube is unscrewed and exactly 0.2 milliliters of sample material is taken with the pipette. Immediately after this, the cap is screwed back on and the test tube is placed back in the tray. Finally, the pipette contents are placed in the reagent substrate and sent for further laboratory evaluation. In this evaluation, genetic material of the SARS-CoV-2 virus can be detected, provided that the test person who gave the specific sample secretion is infected. Since this only becomes evident after completion of the analysis process, all test tubes including screw caps and pipettes must be assumed to be contaminated during sample handling. Nothing must go wrong here, nothing must fall off!
Zero error process is indispensable in the test procedure
Even if a laboratory were in a position in terms of personnel to handle, process and evaluate the daily tests manually, the "human factor of uncertainty" remains: On the one hand, two hands are hardly sufficient to safely manage sample handling without intermediate storage. On the other hand, the permanently repeated unscrewing and screwing on of the tube caps is unergonomic and mentally tiring. The screw caps, which were put on manually in the test centers, fit differently and can possibly be tilted. And finally, a person is probably not capable per se of delivering zero-defect performance over hours. But in the case of the Corona tests, this is absolutely necessary. On the one hand, to rule out procedural errors and thus false test results. On the other hand, to prevent any virus-contaminated material from being released into the laboratory environment under any circumstances. Both would have far-reaching consequences.
Fully automated test sequence - without example and "developed from scratch".
The key to solving this anything but trivial challenge is automation. The special machine builder Femitec in Neusäß near Augsburg has developed a robotic cell for a well-known laboratory company, which precisely maps this handling process in a customized manner and carries it out completely automatically. The automation cell can be flexibly expanded and converted and is suitable for continuous operation. Development started in December 2020, and the cell was delivered in April 2021. "We developed from scratch," says Raimund Geh, a member of the management team at Femitec. "There was no sample or example for this cell," he indicates. "After all, an automated PCR test analysis station didn't exist before, and it was clear from the start that the system had to work one hundred percent safely in every respect." It was also clear that the boundary conditions were challenging. This is because plastic tubes from different manufacturers come out of the test stations, in different sizes, often with different wall thicknesses. The material gives way when gripped, Raimund Geh points out. In addition, the tubes are screwed together manually, each with a different force. The plastic thread may also be damaged or uneven. The challenge was mastered by choosing a flexibly controllable gripper that is explicitly suitable for applications in laboratory automation.
Project development at top speed
After a total development time of only five months, the automation solution was delivered to the test laboratory. Since then, it has been working smoothly and is a novelty in terms of laboratory automation technology: One of the two installed FD-H5 six-axis jointed-arm robots from OTC DAIHEN picks up the plastic residual tubes in parallel from two trays - one on the right, one on the left - as they are delivered from the test center to the laboratory. Attendance is checked at a light barrier, the sample is mixed at a vibrating pad, and barcode entry, opening of the screw cap and holding of the cap are performed at two stations in parallel. Meanwhile, the second robot picks up a pipette, removes the precisely defined sample volume of 0.2 milliliters and feeds it very precisely to the reagent tray for diagnostics. The first robot puts the screw caps back on and places the test tubes back in the tray.
The two robots work cooperatively with each other and exchange all process information in real time. In addition, a total of five grippers are used - three handle the tubes, two grippers hold the screw cap, while a rotary unit unscrews or reseals the tube - non-stop.
"The cell has passed all contamination tests on the part of the laboratory: No material is carried away at any point during the process, and the suction system works perfectly," concludes Raimund Geh with satisfaction.