Falko Schmidt presented his PhD half-time seminar

About mid-way through his PhD, Falko Schmidt presented his past research activities and gave an outlook on his future projects. The topics range from miniaturised machines to self-assembled active molecules activated by light to machine-learning techniques to better characterise dynamical behaviour of microscopic systems.

The seminar will be held at the Department of Physics at Gothenburg University, June 10th 2019 starting at 12:15 p.m.

Presentation by F. Schmidt at the OSA Biophotonics Congress, Tucson, 16 Apr 2019

Light-driven Assembly and Optical Manipulation of Active Colloidal Molecules

Falko Schmidt, Benno Liebchen, Hartmut Loewen & Giovanni Volpe
OSA Biophotonics Congress, Tucson (AZ), USA
16 April 2019

Active matter, consisting of self-propelled units locally injecting energy into the system, opens new horizons for the creation of functional soft materials with designable properties. Experiencing a constant energy input, allows active matter to self-assemble into phases with a complex architecture and functionality such as living clusters which dynamically form, reshape and break-up but would be forbidden in equilibrium material by the entropy maximization (or free energy minimization) principle. The challenge to control this active self-assembly has evoked widespread efforts typically hinging on an engineering of the properties of individual motile constituents. Here, we provide a different route, where activity occurs as an emergent phenomenon only when individual building blocks bind together, in a way which we control by laser light. Using experiments and simulations of two species of immotile microspheres, we exemplify this route by creating active molecules featuring a complex array of behaviors, becoming migrators, spinners and rotators. The possibility to control the dynamics of active self-assembly via light-controllable nonreciprocal interactions will inspire new approaches to understand living matter and to design active materials.

Session: Nanothermodynamics
8:00 AM–10:00 AM, Tuesday, April 16, 2019
Chair: Agnese Callegari; Bilkent University, Turkey

Presentation by F. Schmidt at the Gothenburg Nanophotonic Symposium, 26 Mar 2019

Gothenburg Nanophotonic Symposium 2019

The first symposium on the topic of Nanophotonics brings together researchers from physics and chemistry departments in Gothenburg to present their work and share ideas.

Organised by Dr. R. Verre from the Bionanophotonic group at Chalmers University of Technology seven different groups will be present among which F. Schmidt will represent our Softmatter division of Gothenburg University.

The symposium will take place on the 26th of March 2019 at Kollektorn in MC2, Chalmers Campus. Everybody is welcome to attend!

Jalpa Soni and Falko Schmidt at the Lindau Nobel Laureate Meeting

Jalpa Soni and Falko Schmidt have been nominated by the Marie-Curie association and the Ragnar-Söderbergs foundation to attend the 69th Lindau Nobel Laureate Meeting from the 30 June till 5 July 2019. Congratulations to both!

The Lindau Nobel Laureate Meeting is an annual scientific conference that brings together Nobel laureates and young scientists to encourage scientific exchange among different generations and cultures.
The 69th meeting will be dedicated to Physics, where 580 young scientist from 88 countries will be present.

Talk by F. Schmidt at APS March Meeting 2019, Boston, 6 Mar 2019

Light-driven Assembly of Motile Colloidal Clusters from Immotile Building Blocks
Falko Schmidt, Benno Liebchen, Hartmut Löwen & Giovanni Volpe
APS March Meeting 2019, Boston, USA
6 March 2019 at 8:36-8:48 a.m., Room 258B

Active matter, consisting of self-propelled units locally injecting energy into the system, opens new horizons for the creation of functional soft materials with designable properties. Experiencing a constant energy input, allows active matter to self-assemble into phases with a complex architecture and functionality such as living clusters which dynamically form, reshape and break-up but would be forbidden in equilibrium material by the entropy maximization (or free energy minimization) principle. The challenge to control this active self-assembly has evoked widespread efforts typically hinging on an engineering of the properties of individual motile constituents. Here, we provide a different route, where activity occurs as an emergent phenomenon only when individual building blocks bind together, in a way which we control by laser light. Using experiments and simulations of two species of immotile microspheres, we exemplify this route by creating active molecules featuring a complex array of behaviors, becoming migrators, spinners and rotators. The possibility to control the dynamics of active self-assembly via light-controllable nonreciprocal interactions will inspire new approaches to understand living matter and to design active materials.

Reference: Schmidt et al. Light-controlled Assembly of Active Colloidal Molecules arXiv:1801.06868 (2018)

Talk by F. Schmidt at IONS Scandinavia 2018, Copenhagen, 5-9 Jun 2018

Light-controlled Assembly of Active Colloidal Molecules
Falko Schmidt, Benno Liebchen, Hartmut Löwen & Giovanni Volpe
IONS Scandinavia 2018, Copenhagen, Denmark
5-9 June 2018

We experimentally demonstrate the light-controlled assembly of active colloidal molecules from a suspension of two species of passive microspheres. When light is shone on the sample, the ac- tive molecules form and acquire motility through non-reciprocal interactions between their passive components. As their size grows, they feature a complex array of behaviors, becoming propellers, spinners and rotators. Their shape and functionality can be tuned by applying periodic illumination. We also provide a theoretical model allowing to predict the complete table of emerging active molecules and their properties in quantitative agreement with the experiments.

Reference: Schmidt et al. Light-controlled Assembly of Active Colloidal Molecules arXiv:1801.06868 (2018)

Talk by F. Schmidt at the APS March Meeting, Los Angeles, 8 Mar 2018

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.

References:
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