Cooperation and Phase Separation in a Swarm of Light-Driven Fuel-Free Microswimmers
Matan Yah Ben Zion (Gulliver, ESPCI)
| When |
Mar 24, 2020
from 10:45 to 11:45 |
|---|---|
| Where | Room André Collet (M6) |
| Attendees |
Matan Ben Zion - ANNULE |
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Artificial micron size swimmers typically rely on a chemical fuel for their propulsion - the individual swimmer is too small to hold a fuel tank, and operates only when submerged inside its own fuel. Cooperation between many swimmers is thus restricted, as competition over fuel reduces the individual swimmer's performance. We developed micro-swimmers that consume no chemical fuel and are driven solely by light. We synthesized a hybrid colloidal dimer made of a light absorbing particle coupled to a fluid particle. When shone upon, the light absorbing particle creates a local temperature gradient driving thermo-capillary action in the fluid particle leading to propulsion. The individual swimmer motility can be switched on/off, tuned continuously with the laser power, and externally stirred using magnetic fields. The swimmers' fuel independence allows them to operate, and remain active, for long duration (days), and at high concentrations (dense packing). With increasing concentration, the collective behaviour of the swimmers displays a transition from an isotropic phase to swarming, going from schooling to aggregation, and can cooperate to coral passive particles.