Active elastic solids
Active solids are elastic structures made of, or doped with active units. They are particularly relevant when studying dense biological systems, like confined cell monolayers, dense bacterial suspensions, bacterial biofilms, and dense pedestrian crowds. We develop a minimal experimental realization of an active solid by embedding self-propelled robots at the nodes of an elastic spring network. Moreover, we demonstrate the presence of a feedback between structural deformations and the orientation of active forces, which can give rise to emergent locomotion and to fascinating self-oscillating dynamics called collective actuation.
- Selective and collective actuation in active solids, P. Baconnier, D. Shohat, C. Hernandèz, C. Coulais, V. Démery, G. Düring, and O. Dauchot, Nature Physics, 2022.
- Discontinuous tension-controlled transition between collective actuations in active solids, P. Baconnier, D. Shohat, and O. Dauchot, Physical Review Letters, 2023.
- Noise-induced collective actuation in active solids, P. Baconnier, V. Démery, O. Dauchot, Physical Review E, 2024.
- Model of active solids: rigid body motion and shape-changing mechanisms, C. Hernández-López, P. Baconnier, C. Coulais, O. Dauchot, G. Düring, Physical Review Letters, 2024.
- Self-aligning polar active matter, P. Baconnier, O. Dauchot, V. Démery, G. Düring, S. Henkes, C. Huepe, A. Shee, Reviews of Modern Physics, 2025.
- Reentrant transition to collective actuation in active solids with a polarizing field, P. Baconnier, M. Aksil, V. Démery, O. Dauchot, arXiv:2504.08572, 2025.
- Collective actuation in active solids in the presence of a polarizing field: a review of the dynamical regimes, P. Baconnier, V. Démery, O. Dauchot, arXiv:2504.08599, 2025.
Memory and aging in amorphous materials
Amorphous materials such as crumpled sheets, steel wool, and shape-memory alloys are intrinsically out of equilibrium, since thermal energy is too weak for them to explore their energy landscape. As a result, they can exhibit a wide range of history-dependent responses, as well as aging and memory effects. For example, the memory of a duration can be retained through the Kovacs effect, or the memory of a driving amplitude can be encoded and retrieved through return-point memory. These phenomena are generally rationalized with models of non-interacting binary element (e.g., spins, or hysterons) driven by an external field. Recently, it was shown that including interactions not only allows to better explain experimental results, but also to rationalize more complex memory effects. Yet, the understanding of memory formation in matter remains in its infancy. Combining experiments with different amorphous materials, simulations, and theory, we explore novel aging phenomena and memory effects in amorphous materials, with a particular focus on the response to cyclic driving. Moreover, we explore the possiblity to realize networks of active binary elements, bridging the gap between active matter and memory formation in matter.
- Dynamic self-loops in networks of passive and active binary elements, P. Baconnier, M. Teunisse, M. van Hecke, arXiv:2412.12658, 2024.
- Aging of amorphous materials under cyclic strain, D. Shohat*, P. Baconnier*, I. Procaccia, M. van Hecke, Y. Lahini, arXiv:2506.08779, 2025.
- Memories and motifs in massively multistable materials, P. Baconnier, S. Roy, A. Paliovaios, L. Jin, M. van Hecke, In preparation.
- Two-dimensional return-point memory, C.M. Meulblok, P. Baconnier, M. van Hecke, In preparation.
Autonomous ciliary walkers
Brainless microorganisms such as bacteria and placozoans often rely on arrays of cilia to navigate their environment. The coordinated motion of the cilia enables locomotion, while allowing the organism to respond to its surroundings through physical interactions. Inspired by such systems, we introduce soft robotic walkers that convert vertical vibration into planar locomotion using synthetic buckled cilia. Each cilia can adopt distinct buckled configurations, leading to the emergence of multiple collective locomotion modes. Without electronics or external control, the walkers also autonomously switch between these modes through interactions with the environment. We uncover the mechanisms underlying multimodal locomotion, and demonstrates how coupled mechanical instabilities can give rise to autonomous behaviors.
- Autonomous switching of locomotion behaviors in ciliary walkers, S. Mohanty, P. Baconnier, H. Schomaker, A. Comoretto, M. van Hecke, J.T.B. Overvelde, In preparation.
PhD defense
- PhD Manuscript, 2023 [pdf]