Researchers Construct Tiny, Floating 'Eyeballs,' 'Billiard Balls' on Microchip

January 17, 2005
One of the anisotropic

North Carolina State University chemical engineers have discovered a way to construct new microscopic devices that can act like tiny factories for materials with potential for a wide variety of chemical and biological uses.
The NC State researchers, advised by Dr. Orlin Velev, assistant professor of chemical and biomolecular engineering, include undergraduate student Jeffrey R. Millman and graduate students Ketan H. Bhatt and Brian G. Prevo. They created different types of tiny particles that could eventually be used in everything from drug delivery to determinations of the presence or concentration of biological molecules.

Image: One of the anisotropic “eyeball” particles created by NC State researchers.

Some types of new particles look like microscopic eyeballs, but are really made of tiny particles of gold and latex. Others look like billiard balls, but are slivers of gold, silica and colored latex beads.

The research is published in the January edition of Nature Materials.

“We’re looking at scaling down microfabrication by making special microfluidic chips that can serve as microscopic factories,” Velev says. “All sorts of particulate materials – electrically conductive, magnetic, polymer, metallic, fluorescent – can be combined for special high-tech applications.”

In 2003, Velev and his students published in the journal Nature a technique to control the movement of microscopic droplets of liquid freely floating across centimeter-sized chips packed with electrodes. The breakthrough came as the researchers learned how to circumvent friction by suspending the droplets of water inside fluorinated oil, and then applying electrical voltages to make the liquid hover over the electrical circuits of the chip. Switching the chip’s electrodes on and off – either manually or with the aid of a computer – lets researchers move the droplets across the oil surface to any location on the chip.

In the current research, the NC State scientists create anisotropic particles, or particles with different layers or properties, on the microfluidic chip. The droplets contain tiny amounts of different materials, like gold and latex, along with a small amount of water; the scientists combine them and allow them to dry. The dried particles take on the look of eyeballs, with the gold slivers making a dark dot inside the latex white of the eye.

In the billiard-ball particles, tiny pieces of gold, silica microspheres, yellow latex beads and water resemble something similar to a yellow-and-white striped nine-ball in billiards after drying, with the latex beads clustering at the top of the particle, the gold slivers forming a stripe of brown in the middle of the particle, and the silica microspheres congregating at the bottom of the particle. Similar striped particles were formed from tiny gold slivers, red latex beads and silica microspheres.

“The eyeball and striped particles could be used in electronic paper and as barcoded tags in biological and environmental research,” Velev says, “as well as in advanced drug delivery and targeted therapeutics.”

The research is funded by Velev’s National Science Foundation Career Award.

Paper: “Anisotropic Particle Synthesis in Dielectrophoretically Controlled Microdroplet Reactors”
Authors: Jeffrey R. Millman, Ketan H. Bhatt, Brian T. Prevo and Dr. Orlin D. Velev, NC State University
Published: Jan. 2005, in Nature Materials

Source: North Carolina State University

Explore further: 1 room -- 63 different dust particles: Researchers aim to build dust library

Related Stories

'Nanocavity' Sensor Detects Virus-Sized Particles

December 20, 2007

Scientists have created a nanoscale device that is capable of detecting one quadrillionth of a gram of biological matter, or about the size of certain viruses. In the future, the sensor may be able to detect influenza, severe ...

Microfabrication: The light approach

March 4, 2011

Materials that conduct electricity but which are also transparent to light are important for electronic displays, cameras and solar cells. The industry’s standard material for these applications is indium tin oxide (ITO), ...

Marathon of Nano-Sprinters

November 16, 2005

Processive bio-molecular motors, which move actively along cytoskeletal filaments, drive the cargo traffic in cells and in biomimetic systems. A single motor molecule is sufficient for continuous transport of cargoes such ...

Recommended for you

Hubble catches a transformation in the Virgo constellation

December 9, 2016

The constellation of Virgo (The Virgin) is especially rich in galaxies, due in part to the presence of a massive and gravitationally-bound collection of over 1300 galaxies called the Virgo Cluster. One particular member of ...

Blueprint for shape in ancient land plants

December 9, 2016

Scientists from the Universities of Bristol and Cambridge have unlocked the secrets of shape in the most ancient of land plants using time-lapse imaging, growth analysis and computer modelling.

Hydrogen from sunlight—but as a dark reaction

December 9, 2016

The storage of photogenerated electric energy and its release on demand are still among the main obstacles in artificial photosynthesis. One of the most promising, recently identified photocatalytic new materials is inexpensive ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.