Prof. Kruss, detecting bacteria and viruses in real time sounds like a great prospect for the future. Can you explain how your planned detectors work?

We are working on nanosensors that can be imagined as extremely small tubes – 100,000 times smaller than a human hair. They glow in a range that is not visible to humans (near infrared light). These nanotubes can now be chemically modified to change their glowing in the presence of a specific target molecule. In this way, the presence of virus particles or bacteria is visually detected. What is special about our sensors is that they can be used for a wide range of applications and are extremely small, fast and ultrasensitive. The current situation shows that much more diagnostics should be available to contain pandemics. Imagine having biosensors which are available to everyone, would give a result in minutes and would not be as error-prone as current tests.

What further research is needed to make it real?

We can already distinguish important pathogens such as bacteria in our laboratory. Thinking about all the applications, we want to expand the detection strategies further to be able to detect as many things as possible at the same time. Furthermore, we are also working on a prototype for reading out the nanosensors. In the long term, however, we aim to use such sensor concepts much closer to the patient. One example are intelligent implants that are applied non-invasively and indicate infections without contact.

How can we imagine such a detection device?

Biosensors detect chemical structures that are characteristic of a particular issue. An example would be the protein that allows the coronavirus to enter human cells. The nanosensors recognize precisely these structures. Therefore, such nanosensors, for example integrated in a hydrogel or on paper, are always needed. The readout can then be done with a wide variety of devices or detectors optimized for this purpose.

What role do microelectronics play in your project?

Our nanosensors provide precise information about biological samples. To receive the information, light is used and this must be detected. Single photon detectors from the Fraunhofer Institute for Microelectronic Circuits and Systems IMS are used for this purpose. In addition, a highly integrated device must be developed for a biosensor that can be used by end customers, in which microelectronics and optics play a decisive role.

Why did you decide to advance your research at Fraunhofer IMS?

The development of biosensor technology requires expertise from various fields: From chemistry and physics to engineering and medicine. The Fraunhofer IMS provides an excellent expertise in the field of system integration and in highly sensitive optical detectors. This complements perfectly with my expertise in nanosensors. Together, we can develop the next generation of diagnostic tools.

Sebastian Kruss studied chemistry and biophysics at the University of Heidelberg and earned his doctorate at the Max Planck Institute for Intelligent Systems on nanostructured surfaces. He then moved for a post-doctoral stay to the Massachusetts Institute of Technology (M.I.T.) in Cambridge, USA. After his return, he initially led a research group at the University of Göttingen. In 2020, he was appointed to a professorship in physical chemistry at Ruhr University Bochum. At the same time, he established the biosensors group at the Fraunhofer IMS as part of the Attract program.