Self-solidifying active droplets showing memory-induced chirality

Authors:
  • KFKai Feng
    Kai Feng
  • JMJosé Carlos Ureña Marcos
    José Carlos Ureña Marcos
  • AMAritra K. Mukhopadhyay
    Aritra K. Mukhopadhyay
  • RNRan Niu
    Ran Niu
  • QZQiang Zhao
    Qiang Zhao
  • JQJinping Qu
    Jinping Qu
  • BLBenno Liebchen
    Benno Liebchen
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Abstract
Most synthetic microswimmers do not reach the autonomy of their biological counterparts in terms of energy supply and diversity of motion. Here we report the first all-aqueous droplet swimmer powered by self-generated polyelectrolyte gradients, which shows memory-induced chirality while self-solidifying. An aqueous solution of surface tension-lowering polyelectrolytes self-solidifies on the surface of acidic water, during which polyelectrolytes are gradually emitted into the surrounding water and induce linear self-propulsion via spontaneous symmetry breaking. The low diffusion coefficient of the polyelectrolytes leads to long-lived chemical trails which cause memory effects that drive a transition from linear to chiral motion without requiring any imposed symmetry breaking. The droplet swimmer is capable of highly efficient removal (up to 85%) of uranium from aqueous solutions within 90 min, benefiting from self-propulsion and flow-induced mixing. Our results provide a route to fueling self-propelled agents which can autonomously perform chiral motion and collect toxins.