Analysis of Cargo Loading Modes and Capacity of an Electrically-Powered Active Carrier

TL;DR

This paper investigates how the frequency and voltage influence cargo loading and transport in active Janus particle carriers, revealing optimal conditions and mechanisms for targeted electrokinetic cargo delivery.

Contribution

It characterizes cargo loading properties of Janus carriers across various frequencies and voltages, highlighting the effects of different transport modes and dielectrophoretic trapping.

Findings

Cargo trapping reduces carrier velocity, especially at low frequencies.

Maximum cargo capacity decreases at high voltages, indicating interplay with hydrodynamic shear.

Frequency control enables selective assembly of colloidal solutions.

Abstract

The use of active colloids for cargo transport offers unique potential for applications ranging from targeted drug delivery to lab-on-a-chip systems. Previously, Janus particles (JPs), acting as mobile microelectrodes have been shown to transport cargo which is trapped by a dielectrophoretic mechanism [Boymelgreen et al. (2018)]. Herein, we aim to characterize the cargo loading properties of mobile Janus carriers, across a broad range of frequencies and voltages. In expanding the frequency range of the carrier, we are able to compare the influence of different modes of carrier transport on the loading capacity as well as highlight the differences between cargo trapped by positive and negative dielectrophoresis. Specifically it is shown that cargo trapping results in a reduction in carrier velocities with this effect more pronounced at low frequencies where cargo is trapped close to the substrate. Interestingly, we observe the existence of a maximum cargo loading capacity which decreases at large voltages suggesting a strong interplay between trapping and hydrodynamic shear. Finally, we demonstrate that control of the frequency can enable different assemblies of binary colloidal solutions on the JP. The resultant findings enable the optimization of electrokinetic cargo transport and its selective application to a broad range of targets.