# Nonlinear Electrophoresis of Highly Charged Nonpolarizable Particles

## TL;DR

This study systematically investigates the nonlinear electrophoretic behavior of highly charged submicron particles in high electric fields, revealing effects like particle trapping that are relevant for practical applications.

## Contribution

The paper provides experimental evidence of nonlinear electrophoresis in highly charged particles at accessible field strengths, addressing previous theoretical and experimental inconsistencies.

## Key findings

- Nonlinear effects occur at practical electric fields and surface charges.
- Particles exhibit trapping behavior due to nonlinear electrophoresis.
- Velocity measurements confirm the presence of nonlinear responses.

## Abstract

Nonlinear field dependence of electrophoresis in high fields has been investigated theoretically, yet experimental studies have failed to reach consensus on the effect. In this work, we present a systematic study on the nonlinear electrophoresis of highly charged submicron particles in applied electric fields of up to several kV/cm. First, the particles are characterized in the low-field regime at different salt concentrations and the surface charge density is estimated. Subsequently, we use microfluidic channels and video tracking to systematically characterize the nonlinear response over a range of field strengths. Using velocity measurements on the single particle level, we prove that nonlinear effects are present at electric fields and surface charge densities that are accessible in practical conditions. Finally, we show that nonlinear behavior leads to unexpected particle trapping in channels.