Artificial Rheotaxis

TL;DR

This paper introduces synthetic self-propelled particles capable of positive rheotaxis, mimicking microorganism motility by physically responding to flow, and demonstrates their ability to sense and organize in flow environments.

Contribution

The study designs and characterizes artificial particles that exhibit rheotaxis through a physical mechanism, advancing biomimetic micro-systems with environmental sensing capabilities.

Findings

Experimental data matches a simple overdamped Brownian pendulum model.

Particles can sense flow and organize predictably in diverging flow regions.

Demonstrates a step towards biomimetic systems with environmental responsiveness.

Abstract

Motility is a basic feature of living microorganisms, and how it works is often determined by environmental cues. Recent efforts have focused on develop- ing artificial systems that can mimic microorganisms, and in particular their self-propulsion. Here, we report on the design and characterization of syn- thetic self-propelled particles that migrate upstream, known as positive rheo- taxis. This phenomenon results from a purely physical mechanism involving the interplay between the polarity of the particles and their alignment by a viscous torque. We show quantitative agreement between experimental data and a simple model of an overdamped Brownian pendulum. The model no- tably predicts the existence of a stagnation point in a diverging flow. We take advantage of this property to demonstrate that our active particles can sense and predictably organize in an imposed flow. Our colloidal system represents an important step towards the realization of biomimetic micro-systems withthe ability to sense and respond to environmental changes