Invited talk by G. Volpe at the 9th Nordic Workshop on Statistical Physics, Stockholm, 21-23 Mar 2018

Recent Progress on the Experimental Study of Active Matter
Giovanni Volpe
The 9th Nordic Workshop on Statistical Physics: Biological, Complex and Non-equilibrium Systems, NORDITA, Stockholm, Sweden
21-23 March 2018

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.

Special Issue on Biophotonics published in Biomed. Opt. Express

Special Issue on Biophotonics

Biophotonics feature: introduction
Paolo Campagnola, Daniel Cote, Francesco Pavone, Peter Reece, Vivek J. Srinivasan, Tomasz Tkaczyk & Giovanni Volpe
Biomedical Optics Express 9(3), 1229–1231 (2018)
DOI: 10.1364/BOE.9.001229

Seminar by G. Volpe at Chalmers University, Gothenburg, 15 Feb 2018

Active Matter in Complex and Crowded Environments
Giovanni Volpe
Statistics and Biomathematics Seminar
Chalmers University of Technology, Gothenburg, Sweden
15 February 2018

13:15 seminar room MV:L14, Chalmers tvärgata 3

https://www.chalmers.se/en/departments/math/research/seminar-series/statistics-and-biomathematics-seminar/Pages/default.aspx

Microscopic Critical Engine featured in Phys.Org

Microscopic engine powered by critical demixing

Our recent article Microscopic engine powered by critical remixing
by Falko Schmidt, Alessandro Magazzù, Agnese Callegari, Luca Biancofiore, Frank Cichos & Giovanni Volpe, published in Physical Review Letters 120(6), 068004 (2018) has been featured in “Tiny engine powered by demixing fluid” Phys.Org (February 12, 2018)

Microscopic Critical Engine featured in Optics & Photonics News

Microscopic engine powered by critical demixing

Our recent article Microscopic engine powered by critical remixing
by Falko Schmidt, Alessandro Magazzù, Agnese Callegari, Luca Biancofiore, Frank Cichos & Giovanni Volpe, published in Physical Review Letters 120(6), 068004 (2018) has been featured in “Laser + Critical Liquid = Micro-Engine”, Optics & Photonics News (February 12, 2018)

Optics & Photonics News (OPN) is The Optical Society’s monthly news magazine. It provides in-depth coverage of recent developments in the field of optics and offers busy professionals the tools they need to succeed in the optics industry, as well as informative pieces on a variety of topics such as science and society, education, technology and business. OPN strives to make the various facets of this diverse field accessible to researchers, engineers, businesspeople and students. Contributors include scientists and journalists who specialize in the field of optics.

Microscopic Critical Engine featured in APS Physics

Microscopic engine powered by critical demixing

Our recent article Microscopic engine powered by critical remixing
by Falko Schmidt, Alessandro Magazzù, Agnese Callegari, Luca Biancofiore, Frank Cichos & Giovanni Volpe, published in Physical Review Letters 120(6), 068004 (2018) has been featured in “Focus: A Tiny Engine Powered by Light and Liquid Physics”, Physics 11, 16 (February 9, 2018)

Physics provides daily online-only news and commentary about a selection of papers from the APS journals collection. It is aimed at the reader who wants to keep up with highlights of physics research with explanations that don’t rely on complex technical detail.

The category Physics: focus stories features only a few number of articles each week selected among the set of articles published on all the APS journals.
Research articles that have an interdisciplinary character are usually selected, and their explanations are geared toward students and non-experts. Features are written by a journalist for an audience with a general interest in physics.

Microscopic Critical Engine published in Phys. Rev. Lett.

Microscopic engine powered by critical demixing

Microscopic engine powered by critical demixing
Falko Schmidt, Alessandro Magazzù, Agnese Callegari, Luca Biancofiore, Frank Cichos & Giovanni Volpe
Physical Review Letters 120(6), 068004 (2018)
DOI: 10.1103/PhysRevLett.120.068004
arXiv: 1705.03317

We experimentally demonstrate a microscopic engine powered by the local reversible demixing of a critical mixture. We show that, when an absorbing microsphere is optically trapped by a focused laser beam in a sub-critical mixture, it is set into rotation around the optical axis of the beam because of the emergence of diffusiophoretic propulsion. This behavior can be controlled by adjusting the optical power, the temperature, and the criticality of the mixture.

Featured in :
Focus: A Tiny Engine Powered by Light and Liquid Physics”, Physics 11, 16 (February 9, 2018)
Laser + Critical Liquid = Micro-Engine”, Optics & Photonics News (February 12, 2018)
Tiny engine powered by demixing fluid” Phys.Org (February 12, 2018)
Расслаивание растворителя закрутило микрочастицы вокруг лазерного пучка”, N+1: научные статьи, новости, открытия (February 12, 2018)
Tiny engine powered by remixing fluid”, Brinkwire (February 16, 2018)

 

Seminar by G. Volpe at Institute of Protein Biochemistry (CNR), Naples, 25 Jan 2018

Active Matter in Complex and Crowded Environments
Giovanni Volpe
Institute of Protein Biochemistry, National Research Council (CNR), Naples, Italy
25 January 2018

http://www.ibp.cnr.it/news/seminars/thursday-the-25th-prof-giovanni-volpe-active-matter-in-complex-and-crowded-environments

Dynamic Deposition of Particles in Evaporating Droplets published in J. Phys. Chem. Lett.

Dynamic control of particle deposition in evaporating droplets by an external point source vapor

Dynamic control of particle deposition in evaporating droplets by an external point source vapor
Robert Malinowski, Giovanni Volpe, Ivan Parkin & Giorgio Volpe
The Journal of Physical Chemistry Letters 9(3), 659—664 (2018)
DOI: 10.1021/acs.jpclett.7b02831
arXiv: 1801.08218

The deposition of particles on a surface by an evaporating sessile droplet is important for phenomena as diverse as printing, thin-film deposition, and self-assembly. The shape of the final deposit depends on the flows within the droplet during evaporation. These flows are typically determined at the onset of the process by the intrinsic physical, chemical, and geometrical properties of the droplet and its environment. Here, we demonstrate deterministic emergence and real-time control of Marangoni flows within the evaporating droplet by an external point source of vapor. By varying the source location, we can modulate these flows in space and time to pattern colloids on surfaces in a controllable manner.