Prof. Dr. Alexander Rohrbach
Laboratory for Bio- and Nano-Photonics
Department of Microsystems Engineering (IMTEK) and Institute of Physics
University of Freiburg
Georges-Köhler-Allee 102
79110 Freiburg
email: rohrbach(at)imtek.de
TEL. ++49 761 203 7536 (direct) – 7548 (secretary)
Research
Mission: We investigate how light interacts with biological living matter, and how this matter self-organizes upon thermal fluctuations.
Principles: We combine biophysical experiments with novel laser technologies. We use theory and computer simulations to unravel old and new questions in both optics and cell biology.
Microscopy: We concert coherent photons and fields to build better microscopes based on novel concepts, to look beyond resolution limits and to maximise the information transfer in space and time.
Optical traps: We manipulate biophysical reactions by using dynamic optical traps and track the 3D motions of tiny probes with microsecond resolution and nanometre precision.
Cell biophysics: We measure and analyse the fluctuation driven motion of small cellular structures, bacteria and viruses to understand mechanisms of cellular infection and communication.
- Cells interact through a complex molecular machinery with other cells or with bacteria /viruses, all driven by the thermal fluctuations.
- Fast superresolution imaging based on fluorescence or laser scattering to investigate small, highly dynamic processes, such as particle binding and infections
- Optical trapping and 3D interferometric particle tracking for the induction of rare interaction processes between particles and cells
- High-resolution 3D light-sheet imaging of complex media by holographically shaped laser beams using fluorescence and laser scattering
Our Team
Who said working in a lab isn’t fun?
Click on the video to watch us doing our business!
Selected Publications
Ayala, Y. A., R. Omidvar, W. Römer and A. Rohrbach, Thermal fluctuations of the lipid membrane determine particle uptake into Giant Unilamellar Vesicles, Nature Communications (2023)
F. Jünger, D. Ruh, D. Strobel, R. Michiels, D. Huber, … A: Rohrbach, 100 Hz ROCS microscopy correlated with fluorescence reveals cellular dynamics on different spatiotemporal scales, Nature Communications (2022)
Landenberger B, Yatish, Rohrbach A. , Towards non-blind optical tweezing by finding 3D refractive index changes through off-focus interferometric tracking, Nature Communications (2021)
L. Friedrich, A. Rohrbach, Surface imaging beyond the diffraction limit with optically trapped spheres, Nature Nanotechnology (2015)
M. Koch, A. Rohrbach, Object adapted optical trapping and shape tracking of energy switching helical bacteria, Nature Photonics (2012)
F. Fahrbach, A. Rohrbach, Propagation stability of self-reconstructing Bessel beams enables contrast-enhanced imaging in thick media, Nature Communications (2012)
F. Fahrbach, P. Simon, A. Rohrbach, Microscopy with self-reconstructing beams, Nature Photonics (2010)
H. Kress, E. H. K. Stelzer, D. Holzer, F. Buss, G. Griffiths, A. Rohrbach, Filopodia act as phagocytic tentacles and pull with discrete steps and a load-dependent velocity, PNAS (2007)
A. Rohrbach, Stiffness of optical traps: Quantitative agreement between experiment and electromagnetic theory, Phys.Rev.Lett. (2005)
Teaching
Two courses are offered during each winter and summer terms.
News
13.04.2024: Conference FOM-2026– Two people from our group went to the beautiful city of Stockholm (Sweden) to attend the world’s largest conference on Microscopy.
01.12.2025: Welcoming a new Lab member– Paul Kerker starts as a new PhD student in our group.
01.11.2025: Welcoming a new Lab member– Tobias Albiez starts as a new PhD student in our group.
01.10.2025: Welcoming a new Lab member– Robert Schütze starts as a new research associate in our group.
18.09.2025: Hiking Tour – Belchen– Great day hiking with the group to the top of the Belchen mountain — awesome views and good vibes all around.
24.07.2025: PhD Defense– Yatish successfully defends his PhD-Thesis. Congrats Dr. Yatish!
13.04.2024: Conference FOM-2025– Three people from our group went to the vibrant city of Taipei (Taiwan) to attend the world’s largest conference on Microscopy.
05.12.2024: Hiking Tour – Kandel– Great day hiking with the group to the top of the Kandel mountain — awesome views and good vibes all around.
01.07.2024: Welcoming a new Lab member– Nils le Coutre starts as a new PhD student in our group.
24.03.2024: Conference FOM-2024– Five people from our group went to the fascinating city of Genoa (Italy) to attend the world’s largest conference on Microscopy. Alexander is giving a plenary talk about alternative imaging modes with coherent light.
01.11.2023: Welcoming a new Lab member– Yunhao Mei starts as a new PhD student in our group.
19.06.2023: Publication Alert– A paper by us was published in Small: “Making Hidden Cell Particle Interactions Visible by Thermal Noise Frequency Decomposition”.
02.04.2023: Conference FOM-2023– Ten people from our group flew to the amazing city of Porto (Portugal), to attend the world-largest conference on Microscopy.
01.12.2022: Publication Alert– Another paper accepted in Nature Communications: how thermal membrane fluctuations can predict particle uptake.
01.12.2022: Welcoming a new Lab member– Frederik Görlitz starts as a new Postdoc in our group.
04.09.2022: DPG Conference 2022– Nearly the whole group went to the lovely city of Regensburg, and had a good and stimulating conference on biophysics & techniques.
01.09.2022: Publication Alert– A paper by us about a multistep retraction process of filopodia was published in the Biophysical Journal: “Pulling, failing, and adaptive mechanotransduction of macrophage filopodia”.
01.04.2022: Publication Alert– A paper by us about applications of super-resolving rotating coherent scattering (ROCS) microscopy was published in Nature Communications.
02.12.2021: Publication Alert– A paper by us about a new optical tweezers concept was published in Nature Communications.
20.09.2021: Welcoming a new Lab member– Meelad Lalenejad starts as a new PhD student in our lab working on novel light-sheet microscopy techniques.