Skip to main content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Multiple electrokinetic actuators for feedback control of colloidal crystal size

Published

Author(s)

Jaime Juarez, Pramod Mathai, James A. Liddle, Michael Bevan

Abstract

We report a feedback method for controlling the sizes of hexagonally close packed two-dimensional colloidal crystals in a microfluidic quadrupole electrode device. Crystal size, measured by the number of colloidal particles comprising the crystal, is controlled over an order of magnitude range with a variation of less than 10% for colloidal crystals containing 20 to 250 micron-sized silica spheres. The total number of particles in the control region is tracked in real time and alternating applications of electrokinetic mechanisms – either electro-osmosis or negative dielectrophoresis – are actuated to guide the formation of the crystals of the targeted size. Subtle changes in the bounding geometry of the crystal compare well with scaling models of the number of particles on the crystal edge and a geometrical parameter reflecting the degree of hexagonal close packing. This model system gives us the opportunity to explore concepts relevant to the controlled assembly of nanoscale objects for nanomanufacturing.
Citation
Lab on A Chip
Volume
12
Issue
20

Keywords

feedback control, crystal assembly, dielectrophoresis, electroosmotic flow
Created July 27, 2012, Updated November 10, 2018