Dielectrophoretic Equilibrium of Complex Particles

TL;DR

This paper demonstrates how engineered Janus particles with distinct electrical properties can be precisely positioned using dielectrophoretic forces in a quadrupolar electrode array, enabling advanced control for various applications.

Contribution

It introduces a novel method for controlling complex Janus particles' equilibrium positions via frequency tuning in dielectrophoresis, differing from standard spherical particle behavior.

Findings

Engineered Janus particles exhibit force equilibrium due to opposing dielectrophoretic forces.

Equilibrium position can be tuned by frequency in a quadrupolar electrode array.

This approach enables precise positioning for applications like self-assembly and biosensing.

Abstract

In contrast to the commonly used spherical Janus particles, here we used engineered Janus particles that are fabricated using photolithography technique for precise control over their geometry and coated regions. Specifically, we studied a lollipop-shaped complex particle where its head is coated with gold while its tail is left bare. Due to their distinct electrical properties (i.e. electrical polarizability) the particle exhibits force equilibrium where opposite dielectrophoretic forces acting on its head and tail exactly cancel each other to yield a stable equilibrium position. This was realized in a quadrupolar electrode array where the equilibrium position of the engineered particle could be tuned by the frequency. This stands in contrast to the standard dielectrophoretic behavior where the particle shifts positions from either the center of the quad to the very edge of the electrodes when shifting from a negative to positive dielectrophoretic response, respectively. This opens new opportunities for positioning control of such complex particles for self-assembly, biosensing, biomimetic spermatozoa and more.