Active Matter Influence on Coffee Rings published in Soft Matter

Active Matter Alters the Growth Dynamics of Coffee Rings

Active Matter Alters the Growth Dynamics of Coffee Rings
Tuğba Andaç, Pascal Weigmann, Sabareesh K. P. Velu, Erçağ Pinçe, Agnese Callegari, Giorgio Volpe, Giovanni Volpe & Agnese Callegari
Soft Matter 15(7), 1488—1496 (2019)
doi: 10.1039/C8SM01350K
arXiv: 1803.02619

How particles are deposited at the edge of evaporating droplets, i.e. the coffee ring effect, plays a crucial role in phenomena as diverse as thin-film deposition, self-assembly, and biofilm formation. Recently, microorganisms have been shown to passively exploit and alter these deposition dynamics to increase their survival chances under harshening conditions. Here, we show that, as the droplet evaporation rate slows down, bacterial mobility starts playing a major role in determining the growth dynamics of the edge of drying droplets. Such motility-induced dynamics can influence several biophysical phenomena, from the formation of biofilms to the spreading of pathogens in humid environments and on surfaces subject to periodic drying. Analogous dynamics in other active matter systems can be exploited for technological applications in printing, coating, and self-assembly, where the standard coffee-ring effect is often a nuisance.

Seminar by G. Volpe at UNAM, Mexico City, 18 Feb 2019

Optical Tweezers: From critical fluctuations to nanoscopic force measurement
Seminar at Sistemas Complejos y Física Estadística
UNAM – Universidad National de Mexico, Mexico City, Mexico
18 February 2019

I will first give a brief overview of optical trapping and optical manipulation — the invention that has earned Arthur Ashkin the 2019 Nobel Prize in Physics. Then, I will focus on some recent applications where we have used optical tweezers to characterise critical Casimir forces and to manipulate active matter. Finally, I will present a new approach to the calibration of optical forces that we have recently developed in collaboration with UNAM.

 

Colloquium by G. Volpe at ICF, Cuernavaca, 13 Feb 2019

Emergent Complex Behaviour in Active Matter
Giovanni Volpe
Colloquium at Instituto de Ciencias Físicas
Cuernavaca, Morelos, Mexico
13 February 2019

After a brief introduction of active particles, I’ll present some recent advances on the study of active particles in complex and crowded environments.
First, I’ll show that active particles can work as microswimmers and microengines powered by critical fluctuations and controlled by light.
Then, I’ll discuss some examples of behavior of active particles in crowded environments: a few active particles alter the overall dynamics of a system; active particles create metastable clusters and channels; active matter leads to non-Boltzmann distributions and alternative non-equilibrium relations; and active colloidal molecules can be created and controlled by light.
Finally, I’ll present some examples of the behavior of active particles in complex environments: active particles often perform 2D active Brownian motion; active particles at liquid-liquid interfaces behave as active interstitials or as active atoms; and the environment alters the optimal search strategy for active particles in complex topologies.

https://www.fis.unam.mx/coloquios/473/qemergent-complex-behaviour-in-active-matterq

Invited talk by G. Volpe at Interface Dynamics and Dissipation Across the Time and Length-Scales, Tel Aviv, 21 may 2019

Emergent Complex Behaviour in Active Matter
Giovanni Volpe
Invited talk at “Interface Dynamics and Dissipation Across the Time- and Length-Scales”
CECAM Israel Workshop
Tel Aviv University, Tel Aviv, Israel
21-23 May 2019

After a brief introduction of active particles, I’ll present some recent advances on the study of active particles in complex and crowded environments.
First, I’ll show that active particles can work as microswimmers and microengines powered by critical fluctuations and controlled by light.
Then, I’ll discuss some examples of behavior of active particles in crowded environments: a few active particles alter the overall dynamics of a system; active particles create metastable clusters and channels; active matter leads to non-Boltzmann distributions and alternative non-equilibrium relations; and active colloidal molecules can be created and controlled by light.
Finally, I’ll present some examples of the behavior of active particles in complex environments: active particles often perform 2D active Brownian motion; active particles at liquid-liquid interfaces behave as active interstitials or as active atoms; and the environment alters the optimal search strategy for active particles in complex topologies.

https://www3.tau.ac.il/cecam/index.php/events/eventdetail/28/-/interface-dynamics-and-dissipation-across-the-time-and-length-scales#Program

Invited talk by G. Volpe at the 10th Nordic Workshop on Statistical Physics, Stockholm, 20-22 Mar 2019

Soft Matter Meets Deep Learning
Giovanni Volpe
The 10th Nordic Workshop on Statistical Physics: Biological, Complex and Non-equilibrium Systems, NORDITA, Stockholm, Sweden
20-22 March 2019

I will present an overview of recent project where we have proposed new approached to the experimental study of active matter. In particular I will present a new algorithm for the measurement of microscopic force fields and a deep-learning approach to the tracking of microscopic particles.

Seminar by G. Volpe at Tel Aviv University, 6 Mar 2019

Emergent Complex Behaviour in Active Matter
Giovanni Volpe
Light Matter Interaction Center, Tel Aviv University, Israel
6 March 2019

After a brief introduction of active particles, I’ll present some recent advances on the study of active particles in complex and crowded environments.
First, I’ll show that active particles can work as microswimmers and microengines powered by critical fluctuations and controlled by light.
Then, I’ll discuss some examples of behavior of active particles in crowded environments: a few active particles alter the overall dynamics of a system; active particles create metastable clusters and channels; active matter leads to non-Boltzmann distributions and alternative non-equilibrium relations; and active colloidal molecules can be created and controlled by light.
Finally, I’ll present some examples of the behavior of active particles in complex environments: active particles often perform 2D active Brownian motion; active particles at liquid-liquid interfaces behave as active interstitials or as active atoms; and the environment alters the optimal search strategy for active particles in complex topologies.

Seminar on mechanical information and directed cell migration by Vinay Swaminathan from Lund University, Nexus, 1 Apr 2019

Encoding mechanical information through multimolecular structures: Lessons from directed cell migration
Seminar by Vinay Swaminathan
from Wallenberg Center for Molecular Medicine Fellow, Lund University

Interactions between cells and their mechanical environment is a critical regulator of important physiological functions that gets hijacked in diseases such as cancer. One such function is directed cell migration where cells sense physical cues such as stiffness, varying topologies and fluid flow and migrate directionally in response. While we know relatively a lot about how individual molecules respond to forces, we still lack the understanding of how these “force-sensitive” proteins come together to function in a cell to allow it to sense and transmit mechanical information critical for function. In this seminar, I will first discuss the mechanical cues a cell in our body encounters and their role in normal physiology and disease. I will then introduce the primary subcellular structure that mediates interactions between the cell and its mechanical environment- Integrin-based focal adhesions. I will then describe in detail my recent findings on how integrin receptors come together in focal adhesions and act as mechanical compass where the 3-dimensional orientation of these receptors is sensitive to the magnitude and directionality of mechanical information and thus encodes it. I will also describe the unique microscopy technique that facilitated the discovery of this novel molecular organization and bridges the gap between crystal structures and resolution-limited microscopy. I will conclude by looking ahead to what such an organization of molecules tells us about building mechano-sensitive structures in cells, how we can test its role and perturb it during cell function and how this will provide us with novel insights into diseases such as cancer and immune-disorders.

Place: Nexus
Time: 1 April 2019, 15:00