# Propulsion driven by self-oscillation via an electrohydrodynamic instability

## TL;DR

This paper demonstrates a method to induce self-oscillations in bio-inspired microrobots using a uniform electric field, leveraging an elasto-electro-hydrodynamic instability to mimic natural flagella motion.

## Contribution

It introduces a novel approach to achieve self-oscillation in artificial systems through electric field-induced instability, combining theory and simulations.

## Key findings

- Self-oscillations achieved via electric field in microrobots
- Identification of three behaviors: stationary, swimming, spinning
- Oscillations arise from a Hopf bifurcation mechanism

## Abstract

Oscillations of flagella and cilia play an important role in biology, which motivates the idea of functional mimicry as part of bio-inspired applications. Nevertheless, it still remains challenging to drive their artificial counterparts to oscillate via a steady, homogeneous stimulus. Combining theory and simulations, we demonstrate a strategy to achieve this goal by using an elasto-electro-hydrodynamic instability. In particular, we show that applying a uniform DC electric field can produce self-oscillatory motion of a microrobot composed of a dielectric particle and an elastic filament. Upon tuning the electric field and filament elasticity, the microrobot exhibits three distinct behaviors: a stationary state, undulatory swimming and steady spinning, where the swimming behavior stems from an instability emerging through a Hopf bifurcation. Our results imply the feasibility of engineering self-oscillations by leveraging the elasto-viscous response to control the type of bifurcation and the form of instability. We anticipate that our strategy will be useful in a broad range of applications imitating self-oscillatory natural phenomena and biological processes.