Cooperation and Phase Separation in a Swarm of Light-Driven Fuel-Free Microswimmers
Matan Yah Ben Zion (Gulliver, ESPCI)
| When |
Nov 24, 2020
from 10:45 to 11:45 |
|---|---|
| Where | Online |
| Attendees |
Matan Ben Zion |
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Artificial micron sized swimmers typically rely on their surrounding chemical environment to fuel their propulsion — the individual swimmer is too small to hold a fuel tank, and operates only when submerged inside its own fuel. Cooperation 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. The swimmers’ fuel independence allows them to operate, and remain active, for long duration (days), and at high concentrations (dense packing), showing an internal flow structure. Above a critical concentration, swimmers transition from quickly dispersing and schooling, to persistent crowding, and can cooperate to corral passive particles. To achieve fuel independence, swimmers were synthesised from a hybrid colloidal dimer — 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 inside the fluid particle leading to propulsion. The individual swimmer motility can be switched on/off, continuously tuned, and externally stirred using magnetic fields.