All it took was one application

Stefan Arnold is delighted with his job at Sensirion, which he was offered within a very short time


Stefan Arnold studied nanosciences at the University of Basel before going on to complete his doctoral dissertation at the SNI PhD School. Working at the Biozentrum’s Center for Cellular Imaging and Nano Analytics (C-CINA), he developed a platform that allows the automatic preparation of proteins from individual cells for analysis. Key milestones on the road to his dissertation included two patents, four publications, and participation in two Nano Argovia projects. After that, the job application process was quick and easy. Just three weeks after finding an interesting position on the Sensirion AG website, Stefan Arnold was offered his first job as a junior project manager at the Stäfa-based company.

From Fribourg to Basel
At school, Stefan Arnold was most interested in biology and physics. After obtaining his Maturität certificate, Stefan heard about the nanosciences degree program in Basel and traveled from his home city of Fribourg to attend the university’s information day. Wasting no time, he began his degree in nanosciences in 2006. Like so many other nanoscience students, he particularly liked the familiar atmosphere and the sense of team spirit. Another highlight, he says, was the practical work within the block courses, which offer an insight into the work of various research groups.

Project work at C-CINA
The second project was a decisive moment in his career and led him to Dr. Thomas Braun’s group at C-CINA (Biozentrum). There, the plan was for him to develop a microfluidic chip for processing cells in collaboration with the team led by Professor Andreas Hierlemann of the Department of Biosystems Science and Engineering at the Federal Institute of Technology (ETH) Zurich in Basel (D-BSSE). “However, the chip didn’t work as we’d imagined,” says Stefan Arnold. “After doing some online research, I had the idea of developing a system with microcapillaries for processing individual cells.” It did not take long to convince Thomas Braun that this would make a great topic for a master’s thesis, and so Stefan began building a prototype that could be used to isolate proteins from individual cells. After completing his master’s thesis, he left Basel for a nine-month research placement at CSEM (Centre Suisse d’Electronique et de Microtechnique) in Graubünden. Just as he was considering his next step, the SNI PhD School was founded and Thomas Braun offered him the chance to return to Basel and work on a dissertation at the SNI.

A familiar topic and a new beginning
As part of his doctoral dissertation, Stefan initially began developing a microfluidic platform for the isolation of nanocrystals. However, various problems led him to abandon this approach and he returned to analyzing individual cells, a topic he had been enthusiastic about since he worked on it during his master’s thesis. “I completely redeveloped the setup, optimizing the liquid handling, automating many of the steps, and developing and implementing novel preparation methods for electron microscopy. I really enjoyed the engineering work this involved,” he recalls. Thanks to his dedication and four years of development work, the team now has a compact, effective, and largely automated system at its disposal. The first step uses a cell culture to grow the cells whose proteins are to be analyzed. Specific individual cells can then be selected under an optical microscope, the cell membrane is made permeable using an electric field, and the entire content of the cell is sucked up by a microcapillary into a few nanoliters in a matter of seconds. Depending on the planned analysis technique, this lysate is then applied to specific microscope slides for further treatment.

“Unlike when a whole cell culture is processed, this approach gives us a precise overview of the contents of individual cells. It also reduces the stress on the cells, as they are still living in their cell assembly and interacting with one another until a few seconds before processing,” Stefan Arnold explains.

In order to prepare the proteins of individual cells for cryo-electron microscopy, the system was also refined so that it automatically plunges the slide into liquid ethane. “In short, I simply miniaturized and automated Jacques Dubochet’s brilliant idea for vitrifying liquids, for which he was recently awarded the Nobel Prize in Chemistry,” says Stefan Arnold. Stefan and his colleagues registered two patents to protect this development. The researchers patented the system that enables them to control the coating thickness of the applied sample, and also felt that the specific, automated sample preparation process for cryo-electron microscopy was worthy of protection.

Stefan Arnold’s expertise was also in demand in the Nano Argovia SCeNA project, in which he combined his existing setup with other analysis methods. For example, in collaboration with Dr. Gregor Dernick from F. H. Hoffmann-La Roche and Dr. Christian Berchtold from the University of Applied Sciences Northwestern Switzerland (FHNW), two new platforms were developed to analyze the contents of individual cells using protein microarrays and mass spectrometry.

Faster than expected
In March 2017, Stefan Arnold became the second doctoral student to complete a dissertation at the SNI PhD School. As part of the Nano Argovia MiPIS project, he wanted to remain at C-CINA as a postdoc, albeit for a maximum of one year. “I was still enjoying the work, and summers are always great in Basel,” he reminisces. In August, however, he began looking around to see what sort of jobs might appeal to him and came across an interesting advert on the Sensirion website. “I was already very familiar with Sensirion, as we had visited the company during the second semester of our degree, and then later I regularly accompanied students on the excursion to Sensirion,” Stefan tells us.

“I had taken a number of transferable skills courses at the University of Basel during my dissertation, so it was easy for me to complete my CV and write a good cover letter.” Just a week after submitting the application, he was invited for a first interview. “I was then very quickly invited to a second round, and I was on my way home from those meetings when I was offered the job.”

A great fit all round
Since November, Stefan Arnold has been employed at Sensirion in Stäfa as a junior project manager in the Liquid Flow Products development department. As part of this job, he is involved in developing a single-use flow sensor that precisely measures the flow rate of liquids in a channel.

“A sensor of this kind could be used for the accurate measurement of drug infusions in real time,” Stefan explains. In addition, the sensor could record whenever air bubbles passed through the channel and whether the infusion was actually entering the bloodstream. “It’s a lot of fun working at the interface between research and the product,” he says. Having a specific goal in mind was a source of motivation during his doctoral dissertation, and now spurs him on to develop innovative devices that appeal to customers.

In addition to the exciting scientific and technical challenges, the 32-year-old’s first position after his dissertation suits him in every way: The team, the positive collaboration, and the company culture at Sensirion, not to mention the beautiful surroundings, which offer no shortage of ways to enjoy his spare time.