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1. Articles scientifiques
 Flexoelectric fluid membrane vesicles in spherical confinement
Niloufar Abtahi, Lila Bouzar, Nadia SaidiAmroun, Martin Michael Müller 
The morphology of spherically confined flexoelectric fluid membrane vesicles in an ex
ternal uniform electric field is studied numerically. Due to the deformations induced by
the confinement, the membrane becomes polarized resulting in an interaction with the
external field. The equilibrium shapes of the vesicle without electric field can be clas
sified in a geometrical phase diagram as a function of scaled area and reduced volume
[1, 2]. When the area of the membrane is only slightly larger than the area of the con
fining sphere, a single axisymmetric invagination appears. A nonvanishing electric field
induces an additional elongation of the confined vesicle which is either perpendicular or
parallel depending on the sign of the electric field parameter. Higher values of the surface
area or the electric field parameter can reduce the symmetry of the system leading to
more complex folding. We present the resulting shapes and show that transition lines
are shifted in the presence of an electric field. The obtained folding patterns could be of
interest for biophysical and technological applications alike.
Fermer
Plus d'infos
EPL, 131(1): 18001, 2020. Cf. aussi arXiv:2006.04475.
 Isometric bending requires local constraints on free edges
Jemal Guven, Martin Michael Müller, Pablo VázquezMontejo 
While the shape equations describing the equilibrium of an unstretchable thin sheet that is free
to bend are known, the boundary conditions that supplement these equations on free edges have remained elusive.
Intuitively, unstretchability is captured by a constraint on the metric within the bulk. Naïvely one would then
guess that this constraint is enough to ensure that the deformations determining the boundary conditions on these
edges respect the isometry constraint. If matters were this simple, unfortunately, it would imply unbalanced torques
(as well as forces) along the edge unless manifestly unphysical constraints are met by the boundary geometry. In this
article, we identify the source of the problem: not only the local arclength but also the geodesic curvature need to
be constrained explicitly on all free edges. We derive the boundary conditions which follow. In contrast to conventional
wisdom, there is no need to introduce boundary layers. This framework is applied to isolated conical defects, both
with deficit as well, but more briefly, as surplus angles. Using these boundary conditions, we show that the lateral
tension within a circular cone of fixed radius is equal but opposite to the radial compression, and independent of
the deficit angle itself. We proceed to examine the effect of an oblique outer edge on this cone perturbatively
demonstrating that both the correction to the geometry as well as the stress distribution in the cone kicks in at
second order in the eccentricity of the edge.
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Plus d'infos
Math. Mech. Solids, 24: 4051, 2019. Cf. aussi arXiv:1904.05855.
 Helical Superstructure of Intermediate Filaments
Lila Bouzar, Martin Michael Müller, René Messina, Bernd Nöding, Sarah Köster, Hervé Mohrbach, Igor M. Kulić 
Résumé
Plus d'infos
Phys. Rev. Lett., 122: 098101, 2019. Cf. aussi arXiv:1803.04691.
 Vesicle dynamics in confined steady and harmonically modulated Poiseuille flows
Zakaria Boujja, Chaouqi Misbah, Hamid EzZahraouy, Abdelilah Benyoussef, Thomas John, Christian Wagner, Martin Michael Müller 
We present a numerical study of the timedependent motion of a membrane vesicle in a
channel under an imposed flow. In a Poiseuille flow the shape of the vesicle depends on the flow strength,
the mechanical properties of the membrane, and the width of the channel. In a wide parameter region, the
emerging snaking shape shows an oscillatory motion like a swimmer flagella even though the flow is
stationary. We quantify this behavior by the amplitude and frequency of the oscillations of the vesicle's
center of mass. The influence of an amplitude modulation of the imposed flow on the dynamics and shape of
the snaking vesicle is also investigated. We find that this modulationwhen sufficiently smallinduces
a modulation in amplitude and frequency of the center of mass of the snaking vesicle. For large
modulation amplitudes transitions to static shapes are observed.
Fermer
Phys. Rev. E, 98: 043111, 2018. Cf. aussi arXiv:1810.04500.
 Confining a fluid membrane vesicle of toroidal topology in an adhesive hard sphere
Lila Bouzar, Ferhat Menas, Martin Michael Müller 
Résumé
Plus d'infos
IOP Conf. Series: MSE, 186: 012021, 2017.
 Squeezed helical elastica
Lila Bouzar, Martin Michael Müller, Pierre Gosselin, Igor M. Kulić, Hervé Mohrbach 
Résumé
Plus d'infos
Eur. Phys. J. E, 39: 114, 2016. Cf. aussi arXiv:1606.03611.
 How biofilaments twist membranes
Julien Fierling, Albert Johner, Igor M. Kulić, Hervé Mohrbach, Martin Michael Müller 
Résumé
Soft Matter, 12: 5747, 2016.
 Toroidal membrane vesicles in spherical confinement
Lila Bouzar, Ferhat Menas, Martin Michael Müller 
Résumé
Plus d'infos
Phys. Rev. E, 92: 032721, 2015. Cf. aussi arXiv:1509.00765.
 Nonlinear buckling and symmetry breaking of a soft elastic sheet sliding on a cylindrical substrate
Norbert Stoop, Martin Michael Müller 
Résumé
Plus d'infos
Int. J. NonLinear Mech., 75: 115, 2015. Cf. aussi arXiv:1503.05030.
 Crunching Biofilament Rings
Julien Fierling, Martin Michael Müller, Hervé Mohrbach, Albert Johner, Igor M. Kulić 
Résumé
Plus d'infos
Europhys. Lett., 107(6): 68002, 2014. Cf. aussi arXiv:1408.6787.
 Confotronic dynamics of tubular filaments
Osman Kahraman, Hervé Mohrbach, Martin Michael Müller, Igor M. Kulić 
Résumé
Plus d'infos
Soft Matter, 10(16): pp. 28362847, 2014. Cf. aussi arXiv:1312.3106.
 Whirling skirts and rotating cones
Jemal Guven, J. A. Hanna, Martin Michael Müller 
Steady, dihedrally symmetric patterns with sharp peaks may be observed on a spinning skirt, lagging behind the material flow of the fabric. These qualitative features are captured with a minimal model of traveling waves on an inextensible, flexible, generalizedconical sheet rotating about a fixed axis. Conservation laws are used to reduce the dynamics to a quadrature describing a particle in a threeparameter family of potentials. One parameter is associated with the stress in the sheet, aNoether is the current associated with rotational invariance, and the third is a Rossby number which indicates the relative strength of Coriolis forces. Solutions are quantized by enforcing a topology appropriate to a skirt and a particular choice of dihedral symmetry. A perturbative analysis of nearly axisymmetric cones shows that Coriolis effects are essential in establishing skirtlike solutions. Fully nonlinear solutions with threefold symmetry are presented which bear a suggestive resemblance to the observed patterns.
Fermer
New J. Phys., 15: 113055, 2013. Cf. aussi arXiv:1306.2619.
 Myotubularin and PtdIns3P remodel the sarcoplasmic reticulum in muscle in vivo
Leonela Amoasii, Karim Hnia, Gaëtan Chicanne, Andreas Brech, Belinda Simone Cowling, Martin Michael Müller, Yannick Schwab, Pascale Koebel, Arnaud Ferry, Bernard Payrastre, Jocelyn Laporte 
Résumé
J. Cell Sci., 126(8): 1806, 2013.
 Dipoles in thin sheets
Jemal Guven, J. A. Hanna, Osman Kahraman, Martin Michael Müller 
Résumé
Plus d'infos
Eur. Phys. J. E, 36: 106, 2013. Cf. aussi arXiv:1212.3262.
 Fluid membrane vesicles in confinement
Osman Kahraman, Norbert Stoop, Martin Michael Müller 
Résumé
Plus d'infos
New J. Phys., 14: 095021, 2012.
 Petal shapes of sympetaleous flowers: the interplay between growth, geometry and elasticity
Martine Ben Amar, Martin Michael Müller, Miguel Trejo 
Résumé
Plus d'infos
New J. Phys., 14: 085014, 2012. Choisi pour les Highlights of 2012.
 Morphogenesis of membrane invaginations in spherical confinement
Osman Kahraman, Norbert Stoop, Martin Michael Müller 
We study the morphology of a fluid membrane in spherical confinement. When the
area of the membrane is slightly larger than the area of the outer container, a single axisymmetric
invagination is observed. For higher area, selfcontact occurs: the invagination breaks symmetry
and deforms into an ellipsoidlike shape connected to its outer part via a small slit. For even
higher areas, a second invagination forms inside the original invagination. The folding patterns observed
could constitute basic building blocks in the morphogenesis of biological tissues and organelles.
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Plus d'infos
Europhys. Lett., 97(6): 68008, 2012. Cf. aussi arXiv:1201.2518.
 Conical instabilities on paper
Jemal Guven, Martin Michael Müller, Pablo VázquezMontejo 
Résumé
Plus d'infos
J. Phys. A: Math. Theor., 45(1): 015203, 2012. Cf. aussi arXiv:1107.5008.
 Interfacemediated interactions: Entropic forces of curved membranes
Pierre Gosselin, Hervé Mohrbach, Martin Michael Müller 
Particles embedded in a fluctuating interface experience forces and torques
mediated by the deformations and by the thermal fluctuations of the medium.
Considering a system of two cylinders bound to a fluid membrane we show that
the entropic contribution enhances the curvaturemediated repulsion between
the two cylinders. This is contrary to the usual attractive Casimir force in
the absence of curvaturemediated interactions. For a large distance between
the cylinders, we retrieve the renormalization of the surface tension of a
flat membrane due to thermal fluctuations.
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Plus d'infos
Phys. Rev. E, 83(5): 051921, 2011. Cf. aussi arXiv:1011.1221.
 SelfContact and Instabilities in the Anisotropic Growth of Elastic Membranes
Norbert Stoop, Falk K. Wittel, Martine Ben Amar, Martin Michael Müller, Hans J. Herrmann 
We investigate the morphology of thin discs and rings growing in circumferential direction. Recent analytical results suggest that this growth produces symmetric excess cones (econes). We study the stability of such solutions considering selfcontact and bending stress. We show that, contrary to what was assumed in previous analytical solutions, beyond a critical growth factor, no symmetric econe solution is energetically minimal any more. Instead, we obtain skewed econe solutions having lower energy, characterized by a skewness angle and repetitive spiral winding with increasing growth. These results are generalized to discs with varying thickness and rings with holes of different radii.
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Plus d'infos
Phys. Rev. Lett., 105(6): 068101, 2010. Cf. aussi arXiv:1007.1871.
 Cell Model Approach to Membrane Mediated Protein Interactions
Martin Michael Müller, Markus Deserno 
Résumé
Plus d'infos
Prog. Theor. Phys. Suppl., 184: pp. 351363, 2010.
 Hamiltonian formulation of surfaces with constant Gaussian curvature
Miguel Trejo, Martine Ben Amar, Martin Michael Müller 
Résumé
Plus d'infos
J. Phys. A: Math. Theor., 42(42): 425204, 2009.
 Local Membrane Mechanics of PoreSpanning Bilayers
Ingo Mey, Milena Stephan, Eva K. Schmitt, Martin Michael Müller, Martine Ben Amar, Claudia Steinem, Andreas Janshoff 
Résumé
Plus d'infos
J. Am. Chem. Soc., 131(20): pp. 70317039, 2009.
 Elasticity Mapping of PoreSuspending Native Cell Membranes
Bärbel Lorenz, Ingo Mey, Siegfried Steltenkamp, Tamir Fine, Christina Rommel, Martin Michael Müller, Alexander Maiwald, Joachim Wegener, Claudia Steinem, Andreas Janshoff 
Résumé
Plus d'infos
Small, 5(7): pp. 832838, 2009.
 Conical Defects in Growing Sheets
Martin Michael Müller, Martine Ben Amar, Jemal Guven 
Résumé
Plus d'infos
Phys. Rev. Lett., 101(15): 156104, 2008. Cf. aussi arXiv:0807.1814.
 How paper folds: bending with local constraints
Jemal Guven, Martin Michael Müller 
Résumé
Plus d'infos
J. Phys. A: Math. Theor., 41(5): 055203, 2008. Cf. aussi arXiv:0712.0978.
 Contact lines for fluid surface adhesion
Markus Deserno, Martin Michael Müller, Jemal Guven 
Résumé
Plus d'infos
Phys. Rev. E, 76(1): 011605, 2007. Cf. aussi condmat/0703019. Choisi pour le Virtual Journal of Biological Physics Research.
 Balancing torques in membranemediated interactions: Exact results and
numerical illustrations
Martin Michael Müller, Markus Deserno, Jemal Guven 
Résumé
Plus d'infos
Phys. Rev. E, 76(1): 011921, 2007. Cf. aussi condmat/0702340. Choisi pour le Virtual Journal of Biological Physics Research.
 Aggregation and vesiculation of membrane proteins by curvaturemediated
interactions
Benedict J. Reynwar, Gregoria Illya, Vagelis A. Harmandaris, Martin Michael Müller, Kurt Kremer, Markus Deserno 
Membrane remodelling plays an important role in cellular tasks such as endocytosis, vesiculation and protein sorting, and in the biogenesis of organelles such as the endoplasmic reticulum or the Golgi apparatus. It is well established that the remodelling process is aided by specialized proteins that can sense as well as create membrane curvature, and trigger tubulation when added to synthetic liposomes. Because the energy needed for such largescale changes in membrane geometry significantly exceeds the binding energy between individual proteins and between protein and membrane, cooperative action is essential. It has recently been suggested that curvaturemediated attractive interactions could aid cooperation and complement the effects of specific binding events on membrane remodelling. But it is difficult to experimentally isolate curvaturemediated interactions from direct attractions between proteins. Moreover, approximate theories predict repulsion between isotropically curving proteins. Here we use coarsegrained membrane simulations to show that curvatureinducing model proteins adsorbed on lipid bilayer membranes can experience attractive interactions that arise purely as a result of membrane curvature. We find that once a minimal local bending is realized, the effect robustly drives protein cluster formation and subsequent transformation into vesicles with radii that correlate with the local curvature imprint. Owing to its universal nature, curvaturemediated attraction can operate even between proteins lacking any specific interactions, such as newly synthesized and still immature membrane proteins in the endoplasmic reticulum.
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Nature 447(7143): pp. 461464, 2007.
 How to determine local elastic properties of lipid bilayer membranes
from atomicforcemicroscope measurements: A theoretical analysis
Davood Norouzi, Martin Michael Müller, Markus Deserno 
Measurements with an atomic force microscope (AFM) offer a direct way to
probe elastic properties of lipid bilayer membranes locally: provided
the underlying stressstrain relation is known, material parameters such as
surface tension or bending rigidity may be deduced.
In a recent experiment a porespanning membrane was poked with an AFM tip,
yielding a linear behavior of the forceindentation curves. A theoretical
model for this case is presented here which describes these curves in the
framework of Helfrich theory. The linear behavior of the measurements is
reproduced if one neglects the influence of adhesion between tip and membrane.
Including it via an adhesion balance changes the situation significantly:
forcedistance curves cease to be linear, hysteresis and nonzero detachment
forces can show up. The characteristics of this rich scenario are discussed
in detail in this article.
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Plus d'infos
Phys. Rev. E, 74(6): 061914, 2006. Cf. aussi condmat/0602662. Choisi pour le Virtual Journal of Biological Physics Research.
 Mechanical Properties of PoreSpanning Lipid Bilayers Probed by Atomic Force Microscopy
Siegfried Steltenkamp, Martin Michael Müller, Markus Deserno, Christian Hennesthal, Claudia Steinem, Andreas Janshoff 
Résumé
Plus d'infos
Biophys. J., 91(1): pp. 217226, 2006.
 Interface mediated interactions between particles  a geometrical approach
Martin Michael Müller, Markus Deserno, Jemal Guven 
Résumé
Plus d'infos
Phys. Rev. E, 72(6): 061407, 2005. Cf. aussi condmat/0506019. Choisi pour le Virtual Journal of Biological Physics Research.
 Geometry of surfacemediated interactions
Martin Michael Müller, Markus Deserno, Jemal Guven 
Résumé
Plus d'infos
Europhys. Lett., 69(3): pp. 482488, 2005. Cf. aussi condmat/0409043.
2. Livres

New Trends in the Physics and Mechanics of Biological Systems
Lecture Notes of the Les Houches Summer School, vol. 92 (Oxford University Press, 2011),
éd. par Martine Ben Amar, Alain Goriely, Martin Michael Müller et Leticia Cugliandolo.
Chapitre 9 :
The physics of the cell membrane
Martin Michael Müller et Martine Ben Amar.
3. Mémoires

Theoretical examinations of interface mediated interactions between colloidal particles,
mémoire (2004).

Theoretical studies of fluid membrane mechanics, thèse de doctorat (2007).

Symmetry breaking in bioelasticity, thèse d'habilitation à diriger des recherches (2015).
