Effects of a DC offset on an electrothermal microparticle trap assembled with an AC electric field

Abstract

Micro and nano-scale colloidal particles can be rapidly assembled at electrode-electrolyte interfaces in highly organized structures. These particles aggregate through various forces which are, among others, chemical, electrical, and thermal in nature. Patterning biological cells in such structures has high impact applications but it remains a challenge due to their limited viability under said manipulation forces. Rapid electrokinetic patterning (REP) uses AC electrothermal micro-vortices to aggregate both synthetic particles and biological cells. In this work, we explore the effects of a DC offset on a REP trap performance in bio-relevant isotonic medium. REP traps were characterized by measuring the inter-particle distance under different DC offsets, using a Delaunay triangulation. The inter-particle distance was measured in a steady-state trap followed by the disassembly of the aggregate as the REP vortex was turned off. DC offset enhanced the trapping performance for micro-particles suspended in a sugar-based isotonic medium. It was observed that an increasingly negative DC offset increased the steady-state inter-particle distance and reduced the rate of disassembly. However, no such trend was found with positive DC offsets. Changing the offset in small steps (<500 mV) affected only the inter-particle distance whereas, larger steps significantly affected the trap stability and size.

More information

Identifiers

ORCID for Nicolas G. Green: orcid.org/0000-0001-9230-4455

Catalogue record

Export record

Altmetrics