Approximately 10,000 typing kits from newly recruited donors from around the world arrive at the collection center at the DKMS Life Science Lab in Dresden daily. In the laboratory, these samples are analyzed for 24 HLA markers and several other parameters, such as CMV status or blood group. A critical initial step is the faithful transfer of samples to a “test” plate. Since the end of December 2021, the Swabster, a custom-made robot, the first of its kind, performs this step.
For sample preparation, the swabs, i.e. the cheek swab samples of our donors, are removed from the envelope sent with the samples and transferred to a designated well of a 96-well plate. The buccal swab head, which contains the oral mucosal cells of the donor, is separated from the plastic stem, as this would interfere with further processing.
The typical swab to plate transfer, prior to automation, involved three lab technicians creating a virtual panel for 94 donor samples (plus one negative and one positive control per plate), scanning the donor number into the Laboratory Information Management System (LIMS) and faithful manual insertion of the swabs into plate wells corresponding to the donor numbers. All manual repetitive tasks are prone to error, and in our context, have severe consequences. This would lead to annulling an entire set of probes and reinitiating sample acquisition.
The Swabster takes over the cumbersome error-prone manual workflow, resulting in a robust and efficient initial sample processing step. Instead of three lab technicians, only one now is involvd in creating the LIMS panel and transferring the samples to the Swabster. The Swabster automates the moving of the swab to the correct plate well and destemming the head.
"In 2014, I heard about the idea to automate this sample preparation step for the first time," recounts Jan Heinicke, Laboratory Technology and Automation Specialist at DKMS Life Science Lab. "It took a few years before we were able to put the first version of the Swabster into operation. Such a device is not available off the shelf. In cooperation with the engineering office Graul, the robot was built from scratch and tailored to our requirements. Every circuit had to be designed and put on the circuit board. Such a project is a big challenge."
A long testing phase followed the first 2018 version of the Swabster. The components driven by stepper motors ran in a continuous loop for this purpose. Thousands of swabs were cut. The developers had to redesign the cutter several times. Systematic errors were identified and corrected. One particularly persistent problem was the stems of the swabs, because they are easily bent and not always 100% straight. To prevent the Swabster from missing the intended well of the plate and hitting the edge of the plate, two special cameras were installed. They ensure that the cutter always cuts the swab exactly centered over the well. Each configuration change was followed by multiple tests to ensure smooth operation.
The Swabster, after having gone through rigorous validation, is now used productively in the lab. Weaknesses in the system are identified occasionally and then eliminated in collaboration with Stefan Graul, the engineer whose brainchild the Swabster is. Stefan has been actively involved in developments at the lab helping develop innovative devices and tools. The software controlling the Swabster was developed by Christoph Satz, who amongst other accomplishments, was involved in the development of a sensor system analysis software for the Mars Rover.
"The development of the Swabster was lengthy and challenging," says Vinzenz Lange, Chief Technology Officer of DKMS Life Science Lab. "But that didn't stop us from continuing. We are pleased to have finally turned one of the few remaining manual steps into a less error-prone automated step. In the long run, such improvements will benefit the efficiency of our processes and the quality of our typing data."
The current Swabster instrument is still an alpha version. A newer version will arrive at the lab later this year. This model will be capable of creating the two plates needed per donor for HLA and CMV analysis in parallel. Eventually, eight instruments from this version will be available at the lab to process all incoming samples.