Synthetic Active Matter in Three Dimensions

Active matter processes energy from its surroundings, meaning that it is intrinsically non-equilibrium and the laws of statistical mechanics no longer apply. Examples of active matter include living systems (such as flocking birds and bacteria) and (synthetic) active colloids which convert chemicals in their surroundings into energy. The field of active matter is growing rapidly and, as the examples above indicate, underpins much of the physics of living systems. A new non-equilibrium statistical mechanics of active matter is developing, but urgently needs experimental input.

The best controlled systems are synthetic active colloids, but to date these have only been produced in (quasi) two dimensions. Given the profound difference in behavior of conventional passive matter between 2- and 3-dimensions in terms of phase transitions and critical phenomena for example, it is reasonable to suppose that 3d active matter will reveal new physics.

Here we propose to exploit our super-resolution imaging capability to study synthetic active colloids which are sufficiently small (500 nm)1 that they do not sediment significantly under gravity. We shall use dipolar active colloids, wich are a proven technology2 and adapt them to smaller lengthscales we shall require using standard methods of colloid synthesis.

1 Hallett, J. E.; Turci, F. & Royall, C. P. "Local structure in deeply supercooled liquids exhibits growing lengthscales and dynamical correlations", submitted, (2017).

2 Yan, J.; Han, M.; Zhang, J.; Xu, C.; Luijten, E. & Granick, S. "Reconfiguring active particles by electrostatic imbalance" Nature Mater. 15, 1095-1099 (2016).