Biomedical Physics Group

Doctor Kottlarz!

Wed, 16 Sep 2026 00:00:00 +0000

Congratulations to dr. Inga Kottlarz on successfully defending her PhD thesis on the 18th of May earlier this year, not to forget earning the distinction summa cum laude! Her dissertation, entitled “In silico parameter estimation of cardiac tissue models”, focused on new mathematical and computational approaches to better understand atrial fibrillation. We warmly congratulate Inga on this exceptional achievement and wish her all the best for what comes next!

Atrial fibrillation is a common heart rhythm disorder that is linked to serious complications such as stroke and heart failure. In her thesis, Inga approached the problem from two sides: she developed a mathematical model to better understand the electrical behavior of cardiac cells grown from human stem cells, and she introduced a new data assimilation method to learn about cardiac tissue from limited and noisy measurements. This method can help reconstruct properties that are difficult to measure directly, such as the orientation of cardiac muscle fibres and how easily electrical signals travel in different directions. Together, these approaches show how mathematical modelling can help connect experimental observations with otherwise hidden properties of cardiac cells and tissue.

Research Topic: Controlling Cardiac Complexity

Mon, 27 Jul 2026 00:00:00 +0000

Tim De Coster, Stefan Luther, and Ulrich Parlitz are joining forces as Guest Editors of the Research Topic Controlling Cardiac Complexity in Frontiers in Network Physiology. The collection focuses on the mechanisms and control of cardiac complexity, bringing together ideas from network physiology, nonlinear dynamics, computational modelling and experiments. At its core is a fundamental question in cardiac research: how do interactions across many different scales give rise to complex and potentially dangerous heart rhythms?

Cardiac arrhythmias emerge when the normally coordinated electrical waves in the heart are disrupted by factors such as tissue heterogeneity, fibrosis or altered cellular properties. These interactions can produce anything from highly organized rotating waves to seemingly chaotic electrical activity. Understanding these patterns is an important step towards developing more precise ways of controlling them. In particular, concepts from nonlinear dynamics and network physiology could help move beyond interventions that affect large areas of the heart towards more targeted approaches, including low-energy methods for controlling arrhythmias.

Our Research Topic invites theoretical, computational and experimental studies addressing cardiac dynamics across different spatial and temporal scales. By bringing together researchers from different disciplines, our collection aims to connect fundamental insights into cardiac complexity with new approaches for diagnosis and treatment. We are looking forward to seeing the ideas and collaborations that emerge from this collection!

Three representatives from the lab contributed a presentation to the Dynamics Days

Sat, 25 Jul 2026 00:00:00 +0000

There was a great representation of the major research areas of the biomedical physics group at the European stage. Three researchers presented their latest work at Dynamics Days Europe in Lisbon. Their talks were part of a mini-symposium co-organised by a former lab member (dr. T. Lilienkamp) on the complex dynamics of cardiac fibrillation, organised by a former member of the group. The session explored how the heart’s normally well-coordinated electrical and mechanical activity can turn into the rapid and disordered patterns seen in dangerous arrhythmias. Our contributions spanned 4D ultrasound imaging of cardiac mechanics, data assimilation and reconstruction of cardiac tissue properties, nonlinear modelling of cardiac excitation, and experimental studies of arrhythmia dynamics.

Benjamin Weiss gave us a look inside the fibrillating human heart using high-speed 4D ultrasound. By tracking the motion of the heart muscle in three dimensions, this technique can reveal rotating patterns deep inside the heart, also called mechanical rotors. The measurements also picked up short periods in which the otherwise chaotic motion became more synchronized, something that was not visible in the conventional ECG.

Peer Dresscher tackled a different challenge: can we learn about changes inside the heart without having to measure them directly? Changes in the structure of cardiac tissue can affect how electrical signals travel through the heart. By combining measurements of electrical activity with computer models, the presented approach works backwards to reconstruct these hidden tissue properties. In the future, methods like this could help us get a clearer picture of where abnormal electrical conduction comes from.

Tim De Coster looked at what makes cardiac tissue switch from normal electrical activity to abnormal rhythms and back again. Using both computer models and experiments with light-controlled cardiac cells (optogenetics), he explored how small changes in cell behaviour and the timing of incoming electrical waves can have surprisingly large effects. In some cases, simply changing the rhythm of stimulation could switch abnormal activity on or off. The results help us understand how complex arrhythmias can emerge from relatively simple interactions within cardiac tissue.

Tim wins the Science Slam at the MPI-DS Summer Fest

Sat, 04 Jul 2026 00:00:00 +0000

Tim De Coster recently took the stage at the first MPI-DS Science Slam and came home with the win! The topic of the presentation was optogenetics, a technique that uses light to control the activity of biological cells. The challenge: explaining how it works in just a few minutes while keeping the audience engaged and entertained.

For that, slides alone were not enough. A small light-sensitive robot called Steve, created by our engineering workshop, helped demonstrate the basic idea behind optogenetics, while the audience got involved in the presentation themselves. And with a little help from Gru and the Minions, the science came with a good dose of humor. Together, these elements turned a complex research method into something tangible and easy to follow.

The approach clearly worked: the audience voted the presentation the winner of the Science Slam. Congratulations on the great performance and on finding a creative way to bring our research from the lab to the stage!

Doctor Wolter!

Fri, 01 May 2026 00:00:00 +0000

Congratulations to dr. Justine Wolter on successfully defending her PhD thesis on the 26th of February earlier this year! Her dissertation, entitled “Pulse shape optimization for cardiac stimulation - Analyzing the activation of virtual electrodes”, explored new ways to make electrical defibrillation of cardiac arrhythmias more energy-efficient. We congratulate Justine on this important milestone and wish her all the best for what comes next!

Cardiac arrhythmias such as atrial and ventricular fibrillation are commonly treated using electrical shocks, but conventional defibrillation requires high energies that can cause pain and other unwanted effects. In her thesis, Justine investigated how the shape of the electrical pulse influences the energy needed to restore normal cardiac activity. Using computer simulations together with experimental observations, her work compared different stimulation strategies and showed that the most efficient pulse shape depends on the conditions and structures being targeted in the heart. These findings could help guide the development of lower-energy and less painful approaches to defibrillation.

Four weeks of heart physics at KITP

Wed, 29 Apr 2026 00:00:00 +0000

Tim and Stefan spent four weeks at the Kavli Institute for Theoretical Physics (KITP) in Santa Barbara for the program “Multi-Scale Physics of Normal and Diseased Heart: from Ion Channels to Whole Organ”. This program brought together experimentalists, clinicians, physicists, mathematicians and engineers to study cardiac arrhythmias across the many scales of the heart: from molecules and individual cells all the way to the whole organ. Unlike a typical conference, this program was built around an extended stay with relatively few scheduled talks, leaving plenty of time for discussions, collaborative work and developing new ideas together.

Tim De Coster contributed two perspectives on how abnormal cardiac activity develops and how it might be controlled. In one talk, he used nonlinear dynamics to explore how small changes in the properties of heart cells can lead to major changes in their electrical behavior, including abnormal signals linked to arrhythmias. His second contribution focused on feedback control, using optogenetics to monitor cardiac activity and respond with precisely timed light stimulation. By combining an understanding of the underlying dynamics with targeted control, the goal is to stop abnormal activity before it develops into a more serious arrhythmia.

Stefan Luther focused on ways to control dangerous cardiac rhythms using much less energy than conventional defibrillation. His talk on Low Energy Control of Cardiac Arrhythmias explored how insights from nonlinear dynamics and cardiac physics can be used to develop gentler and more targeted approaches for terminating arrhythmias. He also presented at the accompanying teachers’ conference The Physics of the Heart and Teaching BioPhysics in the Classroom, connecting fundamental principles of cardiac dynamics with imaging, control and clinical applications. This provided a chance to share not only current research, but also ways of bringing the physics of the heart into the classroom.

You can find our two trans-Atlantic travelers underneath together with the majority of other researchers selected to partake in the program.

Wed, 16 Sep 2026 00:00:00 +0000

Research Interests

I am specialized in mathematical modelling and computational methods, with a special interest in the biophysics underlying heart rhythm disorders.
I am currently doing research in numerical and theoretical biomedical physics with a focus on nonlinear dynamics, cardiac arrhythmias, and self-termination. The main goal of my project called SASQUATCH (Searching for Arrhythmia Solutions by Quantifying and Unraveling Atrial Transient Chaos) is to find underlying ionic triggers that help in the process of self-termination of dangerous heart rhythm disorders.

Curriculum Vitae


2025-2026	Marie Sklodowska-Curie Postdoctoral Fellow: research project SASQUATCH, MPI-DS, Germany
2024-2025	Postdoctoral Research Associate, LUMC, the Netherlands
2022-2024	ZonMW OffRoad Fellow, Netherlands Heart Institute, the Netherlands
2018-2022	Postdoctoral Research Associate, LUMC, the Netherlands
2014-2019	Ph.D. in Physics & Biomedical Sciences, Ghent University & KU Leuven, Belgium
2012-2014	M.Sc. in Physics, KU Leuven, Belgium
2009-2012	B.Sc. in Physics, KU Leuven, Belgium

Collaborators

H. Hupkes, Leiden University, the Netherlands
M. Chirilus-Bruckner, Leiden University, the Netherlands
D.A. Pijnappels, , Leiden University Medical Center, the Netherlands
A.V. Panfilov, Ghent University, Belgium
U. Parlitz, Max Planck Institute for Dynamics and Self-Organization, Göttingen

J. Kamphuis, D. Kabus, H. Hupkes, T. De Coster
Microscopic Variability Alters Macroscopic Rotation Speed in Stochastic Spiral Waves
arXiv pre-print (2026): https://doi.org/10.48550/arXiv.2511.21710
T. De Coster, A.A.F. de Vries, D.A. Pijnappels, A.V. Panfilov
Spirals and other excitation patterns in the heart
Springer Nature book chapter (2026): https://doi.org/10.1007/978-3-032-08753-9_43
D. Kabus, H. Dierckx, T. De Coster
Pigreads: The Python-integrated GPU-enabled reaction-diffusion solver using OpenCL for cardiac electrophysiology and other applications
Computer Physics Communications (2026): https://doi.org/10.1016/j.cpc.2026.110088
S. Deng, N. Harlaar, J. Zhang, S.O. Dekker, N.N. Kudryashova, H. Zhou, C.I. Bart, T. Jin, G. Derevyanko, A.V. Panfilov, R.H. Poelma, A.A.F. de Vries, G.Q. Zhang, D.A. Pijnappels, T. De Coster
Smart optogenetics for real-time automated control of cardiac electrical activity
Advanced Science (2026): https://doi.org/10.1002/advs.202522759
A.S. Teplenin, N.N. Kudryashova, R. Majumder, A.A.F. de Vries, A.V. Panfilov, D.A. Pijnappels, T. De Coster
Atypical collective oscillatory activity in cardiac tissue uncovered by optogenetics
eLife (2026): https://doi.org/10.7554/eLife.107072
T. De Coster
(Cardiac) complexity needs interaction
Scientific Reports (2025): https://doi.org/10.1038/s41598-025-09349-5
T. De Coster, A. Nobacht, T. Oostendorp, A.A.F. de Vries, R. Coronel, D.A. Pijnappels
Monitoring and modulating cardiac bioelectricity: from Einthoven to End-user
Europace (2024): https://doi.org/10.1093/europace/euae300
S. Deng, B.L. den Ouden, T. De Coster, C.I. Bart, W.H. Bax, R.H. Poelma, A.A.F. de Vries, G.Q. Zhang, V. Portero, D.A. Pijnappels
An Untethered Heart Rhythm Monitoring System with Automated AI-Based Arrhythmia Detection for Closed-Loop Experimental Application
Advanced Sensor Research (2024): https://doi.org/10.1002/adsr.202400057
T. De Coster, A.S. Teplenin, I. Feola, C.I. Bart, A.A. Ramkisoensing, B.L. den Ouden, D.L. Ypey, S.A. Trines, A.V. Panfilov, K. Zeppenfeld, A.A.F. de Vries, D.A. Pijnappels
‘Trapped re-entry’as source of acute focal atrial arrhythmias
Cardiovascular Research Featured (2024): https://doi.org/10.1093/cvr/cvad179
D. Kabus, T. De Coster, A.A.F. de Vries, D.A. Pijnappels, H. Dierckx
Fast creation of data-driven low-order predictive cardiac tissue excitation models from recorded activation patterns
Computers in Biology and Medicine (2024): https://doi.org/10.1016/j.compbiomed.2024.107949
T. De Coster, B. Ordog, S.O. Dekker, C.I. Bart, J. Zhang, G.J.J. Boink, W.H. Bax, S. Deng, B.L. den Ouden, A.A.F. de Vries, D.A. Pijnappels
Opto-electronic feedback control of membrane potential for real-time (re)shaping of action potentials
Cell Reports Methods (2023): https://doi.org/10.1016/j.crmeth.2023.100671
T. De Coster
A shock-free approach for ambulatory cardioversion in atrial fibrillation
American Journal of Physiology-Heart and Circulatory Physiology (2021): https://doi.org/10.1152/ajpheart.00847.2020
V. Biasci, L. Sacconi, E.N. Cytrynbaum, D.A. Pijnappels, T. De Coster, A. Shrier, L. Glass, G. Bub
Universal mechanisms for self-termination of rapid cardiac rhythm
Chaos: An Interdisciplinary Journal of Nonlinear Science Featured (2020): https://doi.org/10.1063/5.0033813
T. De Coster, R. Majumder, N. Kudryashova, A.O. Verkerk, I.V. Kazbanov, B. Ordog, N. Harlaar, R. Wilders, A.A.F. de Vries, D.L. Ypey, A.V. Panfilov, D.A. Pijnappels
Self-restoration of cardiac excitation rhythm by anti-arrhythmic ion channel gating
eLife (2020): https://doi.org/10.7554/eLife.55921
T. De Coster, P. Claus, G. Seemann, R. Willems, K.R. Sipido, A.V. Panfilov
Myocyte remodelling due to fibro-fatty infiltrations influences arrhythmogenicity
Frontiers in Physiology (2018): https://doi.org/10.3389/fphys.2018.01381
T. De Coster, P. Claus, I.V. Kazbanov, P. Haemers, R. Willems, K.R. Sipido, A.V. Panfilov
Arrhythmogenicity of fibro-fatty infiltrations
Scientific Reports (2018): https://doi.org/10.1038/s41598-018-20450-w

Biomedical Physics Group

Doctor Kottlarz!

Research Topic: Controlling Cardiac Complexity

Three representatives from the lab contributed a presentation to the Dynamics Days

Tim wins the Science Slam at the MPI-DS Summer Fest

Doctor Wolter!

Four weeks of heart physics at KITP

Research Interests

Curriculum Vitae

Collaborators

Publications and related works