Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New polyelectrolyte inks create fine-scale structures through direct writing

25.03.2004


Direct-write assembly of 3-D micro-periodic structures. (a) Schematic illustration of the ink deposition process. (b) Three-dimensional periodic structure with a face-centered tetragonal geometry (filament diameter: 1 micron). Images courtesy Jennifer Lewis



Like spiders spinning webs, researchers at the University of Illinois at Urbana-Champaign are creating complex, three-dimensional structures with micron-size features using a robotic deposition process called direct-write assembly.

As reported in the March 25 issue of the journal Nature, Jennifer Lewis and her research team have developed novel inks that readily flow through micro-capillary nozzles and then rapidly solidify to retain their shape. Patterning such fine structures could be useful in applications such as drug-delivery, micro-fluidics, photonics and tissue engineering.

"This research builds upon our previous work with colloid-based inks, and represents a major step forward in both ink design and pattern resolution," said Lewis, a Willett Faculty Scholar and a professor of materials science and engineering and of chemical and biomolecular engineering at Illinois. "Because this new ink is based solely on polyelectrolyte mixtures rather than colloidal particles, we are able to produce three-dimensional periodic structures with feature sizes that are 100 times smaller than before."



The smallest feature size Lewis’ team has demonstrated so far is 500 nanometers. An entire three-dimensional structure can fit in the diameter of a human hair.

"The new inks are low-viscosity fluids created by combining oppositely charged polyelectrolyte complexes," Lewis said. "The ink viscosity can be tailored over a wide range to control its flow through fine deposition nozzles of varying diameter."

A spider creates its web by secreting a concentrated protein solution through its spinneret to produce fine silk filaments. "We drew inspiration from this natural process to guide our ink design," said graduate student Gregory Gratson, who helped develop the inks. "For example, we worked in a similar concentration range as spider-spinning dope, though our ink structure is significantly less complicated."

To produce the desired three-dimensional structure, the extruded ink is deposited into a coagulation reservoir containing deionized water and isopropyl alcohol, Gratson said. Solidification of the ink is induced by electrostatic interactions in a water-rich reservoir or by solvent-quality effects in an alcohol-rich reservoir. A careful balance is needed so that the extruded ink filament is elastic enough to maintain its shape while spanning the structure, but flexible enough to adhere to other filaments. Dispensed from a syringe by a computer-controlled, three-axis micropositioner, the polyelectrolyte ink exits the nozzle as a continuous filament that is deposited into a reservoir on the substrate surface, yielding a two-dimensional pattern. After the first layer is generated, the nozzle is raised and another layer is deposited. This process is repeated until the desired three-dimensional structure is produced.


The precisely patterned parts could be used as bio-scaffolds, micro-fluidic networks, sensor arrays or templates for photonic materials.

Graduate student Mingjie Xu is also a co-author of the paper. The U.S. Department of Energy and the U.S. Army Research Office MURI program funded this work.

James E. Kloeppel | UIUC
Further information:
http://www.news.uiuc.edu/news/04/0324inks.html

More articles from Materials Sciences:

nachricht Siberian scientists suggested a new method for synthesizing a promising magnetic material
23.01.2018 | Siberian Federal University

nachricht Complex tessellations, extraordinary materials
23.01.2018 | Technische Universität München

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Optical Nanoscope Allows Imaging of Quantum Dots

Physicists have developed a technique based on optical microscopy that can be used to create images of atoms on the nanoscale. In particular, the new method allows the imaging of quantum dots in a semiconductor chip. Together with colleagues from the University of Bochum, scientists from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute reported the findings in the journal Nature Photonics.

Microscopes allow us to see structures that are otherwise invisible to the human eye. However, conventional optical microscopes cannot be used to image...

Im Focus: Artificial agent designs quantum experiments

On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.

We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Rutgers scientists discover 'Legos of life'

23.01.2018 | Life Sciences

Seabed mining could destroy ecosystems

23.01.2018 | Earth Sciences

Transportable laser

23.01.2018 | Physics and Astronomy

VideoLinks Science & Research
Overview of more VideoLinks >>>