Self-solidifying active droplets showing memory-induced chirality

TL;DR

This paper introduces a novel all-aqueous droplet swimmer powered by self-generated polyelectrolyte gradients that exhibits memory-induced chirality and can efficiently remove uranium from water.

Contribution

It presents the first self-solidifying, active droplet swimmer driven by polyelectrolyte gradients with autonomous chiral motion and toxin collection capabilities.

Findings

Demonstrated self-solidification and propulsion via polyelectrolyte emission.

Observed memory effects leading to transition from linear to chiral motion.

Achieved up to 85% uranium removal within 90 minutes.

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.