Sensing and communication at the microscale is a challenge for bacteria and other organisms. One mechanism is quorum sensing: through emitting signaling molecules and measuring their concentration, members of a population can get information about the local density. In a collaboration with the Bechinger group in Konstanz, we elucidate the collective dynamics of synthetic swimmers that change their "phenotype" from motile to passive depending on the local concentration.
"Self-organization of active particles by quorum sensing rules" by T. Bäuerle, A. Fischer, T. Speck, and C. Bechinger published in Nat. Commun. 9, 3232 (2018)
Interactions of colloidal particles can be tuned over a wide range. Truly long-range interactions (like gravity) are possible through solvent flow. In this work we demonstrate that colloidal ion reservoirs produce such flows that are well-described as a conservative potential, predicting the dynamics and structure of clusters of a few particles ("molecules"). Read article...
"Self-assembly of colloidal molecules due to self-generated flow" by R. Niu, T. Palberg, and T. Speck, published in Phys. Rev. Lett. 119, 028001 (2017)
Our article "Dynamical mean-field theory and weakly non-linear analysis for the phase separation of active Brownian particles" (Link) has been selected by the Journal of Chemical Physics for the 2015 Editors' Choice collection.
A study of a composite soft-matter nanomechanical system consisting of a rotating ring of optically trapped colloidal particles confining a set of untrapped colloids demonstrates the possibility of gearwheel-like torque transmission on the nanoscale. Read article...
"Transmission of torque at the nanoscale" by Ian Williams, Erdal C Oguz, Thomas Speck, Paul Bartlett, Hartmut Löwen and C. Patrick Royall