Talk by A. Argun at IONS Scandinavia 2018, Copenhagen, 5-9 Jun 18

Experimental realization of a minimal microscopic heat engine
Aykut Argun, Jalpa Soni, Lennart Dabelow, Stefano Bo, Giuseppe Pesce,
Ralf Eichborn & Giovanni Volpe
IONS Scandinavia 2018, Copenhagen, Denmark
5-9 June 2018

Abstract:  Microscopic heat engines are microscale systems that convert energy flows between heat reservoirs into work or systematic motion. We have experimentally realized a minimal microscopic heat engine. It consists of a colloidal Brownian particle optically trapped in an elliptical potential well and simultaneously coupled to two heat baths at different temperatures acting along perpendicular directions. For a generic arrangement of the principal directions of the baths and the potential, the symmetry of the system is broken, such that the heat flow drives a systematic gyrating motion of the particle around the potential minimum. Using the experimentally measured trajectories, we quantify the gyrating motion of the particle, the resulting torque that it exerts on the potential, and the associated heat flow between the heat baths. We find excellent agreement between the experimental results and the theoretical predictions. 

Reference: Argun et al. Experimental realization of a minimal microscopic heat engine. Physical Review E 96(5), 052106 (2017)

Invited talk by G. Volpe at the 9th Nordic Workshop on Statistical Physics, Stockholm, 21-23 Mar 18

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.

Talk by F. Schmidt at the APS March Meeting, Los Angeles, 8 Mar 18

Microscopic Engine Powered by Critical Demixing
Falko Schmidt, Alessandro Magazzu, Agnese Callegari, Luca Biancofiore, Frank Cichos & Giovanni Volpe
APS March Meeting 2018, Los Angeles (CA), USA
5-9 March 2018

During the last few decades much effort has gone into the miniaturization of machines down to the microscopic scale with robotic solutions indispensable in modern industrial processes and play a central role in many biological systems. There has been a quest in understanding the mechanism behind molecular motors and several approaches have been proposed to realize artificial engines capable of converting energy into mechanical work. These current micronsized engines depend on the transfer of angular momentum of light, are driven by external magnetic fields, due to chemical reactions or by the energy flow between two thermal reservoirs [1-5]. Here we propose a new type of engine that is powered by the local, reversible demixing of a critical binary liquid. In particular, we show that an absorbing, optically trapped particle performs revolutions around the optical beam because of the emergence of diffusiophoresis and thereby produces work. This engines is adjustable by the optical power supplied, the temperature of the environment and the criticality of the system.

1. P.A. Quinto-Su, Nat. Comm. (2014).
2. V. Blickle et al., Nat. Phys. (2012).
3. I.A. Martinez et al., Nat. Phys. 12 (2016).
4. S.L. Neale et al., Nat. Mater. (2005).
5. A. Argun et al., arXiv preprint (2017)

Session R57: Active Matter I
8:00 AM–11:00 AM, Thursday, March 8, 2018
LACC Room: 518
Sponsoring Units: GSOFT DBIO GSNP
Chair: Paulo Arratia, Univ of Pennsylvania

Seminar by G. Volpe at Chalmers University, Gothenburg, 15 Feb 18

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

Seminar by G. Volpe at Institute of Protein Biochemistry (CNR), Naples, 25 Jan 18

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