New method for the production of defined microparticles with 3-D nanopatterns

November 15, 2007

Many scientists are working feverishly to develop reliable but simple methods for the production of tiny particles with defined size and shape that are covered with special regular patterns in two or three dimensions and at both the nano- and the microscale. These miniature objects have countless applications in modern technology, from diagnostic systems to the generation of artificial tissues to improved data storage.

A team headed by Edwin L. Thomas and Patrick S. Doyle at MIT in Cambridge, Massachusetts (USA) has now developed a new method for the large-scale synthesis of three-dimensionally patterned polymer particles with morphological characteristics in the submicrometer range. As described in the journal Angewandte Chemie, with the use of stop-flow interference lithography, the team has even been able to produce Janus particles, microparticles with two chemically different hemispheres.

“Our new method is a combination of phase mask interference lithography and mirofluidic flow lithography, unifying the strengths of these two methods,” explain the researchers. Liquid precursors of a polymer whose formation is induced by light are introduced into a microfluidic system (a system of channels that are just a few micrometers wide). The bottom portion of the device is a phase mask with a periodic surface structure.

This arrangement is irradiated through a transparency mask that defines the shape of the resulting particles. In a test sample these were triangles with sides of 60 µm. Once the parallel light rays pass through the strictly periodic surface structure of the phase mask, the result is a complex three-dimensional distribution of light intensity within the liquid (interference).

In regions of high intensity, the polymer precursors are cross-linked to form three-dimensional structures in a solid hydrogel. In this way, the researchers were able to give the triangular particles a knobby, lattice-like structure.

Because this method works continuously, it can attain a very high throughput: Liquid flows in and polymerizes to form particles that are immediately rinsed away when the next portion of liquid follows—all in less than a second. In contrast to other techniques, the liquid does not need to be deposited in an even layer on a support and developed stepwise.

In addition, within a microchannel, it is possible to allow two different liquids to flow side by side without mixing. If the transparency mask is adjusted so that the light irradiates a region around the boundary between the two liquids, the process results in Janus particles with two chemically different hemispheres.

Citation: Edwin L. Thomas, A Route to Three-Dimensional Structures in a Microfluidic Device: Stop-Flow Interference Lithography, Angewandte Chemie International Edition 2007, 46, No. 47, 9027–9031, doi: 10.1002/anie.200703525

Source: Wiley

Explore further: SLAC gears up for dark matter hunt with LUX-ZEPLIN

Related Stories

SLAC gears up for dark matter hunt with LUX-ZEPLIN

May 21, 2015

Researchers have come a step closer to building one of the world's best dark matter detectors: The U.S. Department of Energy (DOE) recently signed off on the conceptual design of the proposed LUX-ZEPLIN (LZ) experiment and ...

Researchers find a new way to clear the air

March 17, 2015

In 1999, then-Chinese Premier Zhu Rongji said that Beijing's pall of smog "would shorten my life at least five years," a hazard level scientists affirmed two years ago with a study of China's air pollution. That reality that ...

ACEs are high with space station colloidal research

August 25, 2014

One global marketer took to space to find a way to be leaner and greener back on Earth. For Procter & Gamble (P&G), product innovation and improvement relied on use of the International Space Station (ISS) as a science platform ...

Recommended for you

Reshaping the solar spectrum to turn light to electricity

July 28, 2015

When it comes to installing solar cells, labor cost and the cost of the land to house them constitute the bulk of the expense. The solar cells—made often of silicon or cadmium telluride—rarely cost more than 20 percent ...

Could stronger, tougher paper replace metal?

July 24, 2015

Researchers at the University of Maryland recently discovered that paper made of cellulose fibers is tougher and stronger the smaller the fibers get. For a long time, engineers have sought a material that is both strong (resistant ...

Wafer-thin material heralds future of wearable technology

July 27, 2015

UOW's Institute for Superconducting and Electronic Materials (ISEM) has successfully pioneered a way to construct a flexible, foldable and lightweight energy storage device that provides the building blocks for next-generation ...

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.