Hydrodynamic pursuit by cognitive self-steering microswimmers

TL;DR

This study investigates how synthetic microswimmers can pursue targets using hydrodynamic interactions and limited sensing, demonstrating stable pursuit strategies and mutual influence on motion.

Contribution

It introduces a model for pursuit strategies in microswimmers with hydrodynamic steering, highlighting how different propulsion types and adaptation schemes enable stable pursuit.

Findings

Stable pursuit states depend on propulsion type and steering scheme.

Mutual influence affects trajectories and pursuit stability.

Hydrodynamic interactions enable cooperative pursuit behaviors.

Abstract

The properties of biological microswimmers are to a large extent determined by fluid-mediated interactions, which govern their propulsion, perception of their surrounding, and the steering of their motion for feeding or in pursuit. Transferring similar functionalities to synthetic microswimmers poses major challenges, and the design of favorable steering and pursuit strategies is fundamental in such an endeavor. Here, we apply a squirmer model to investigate the pursuit of pursuer-target pairs with an implicit sensing mechanism and limited hydrodynamic steering abilities of the pursuer. Two hydrodynamic steering strategies are applied for the pursuer's propulsion direction by adaptation of its surface flow field, (i) reorientation toward the target with limited maneuverability, and (ii) alignment with the target's propulsion direction combined with speed adaptation. Depending on the nature of the microswimmer propulsion (puller, pusher) and the velocity-adaptation scheme, stable cooperatively moving states can be achieved, characterized by specific squirmer arrangements and controllable trajectories. Importantly, pursuer and target mutually affect their motion and trajectories.