Sol-gel inks produce complex shapes with nanoscal...( CHAMPAIGN Ill. New sol-gel inks dev...)

CHAMPAIGN, Ill. New sol-gel inks developed by researchers at the University of Illinois can be printed into patterns to produce three-dimensional structures of metal oxides with nanoscale features.

The ability to directly pattern functional oxides at the nanoscale opens a new avenue to functional devices. Potential applications include micro-fuel cells, photonic crystals and gas sensors.

The researchers describe the new inks in a paper accepted for publication in the journal Advanced Materials, and featured on its Advances in Advance Web site.

Using this new family of inks, we have produced features as small as 225 nanometers, said co-author Jennifer Lewis, the Thurnauer Professor of Materials Science and Engineering and director of the universitys Frederick Seitz Materials Research Laboratory (FSMRL). Our goal is to get down to 100 nanometer feature sizes.

To create three-dimensional structures, the researchers use a robotic deposition process called direct-write assembly. The concentrated sol-gel ink is dispensed as a filament from a nozzle approximately 1 micron in diameter (about 100 times smaller than a human hair). The ink is dispensed while a computer-controlled micropositioner precisely directs the path. After the pattern for the first layer is complete, the nozzle is raised and another layer is deposited. This process is repeated until the desired shape is produced.

We have opened direct ink writing to a new realm of functional materials, said graduate student Eric Duoss, the papers lead author. Since we print the desired functionality directly, the need for complicated templating and replicating schemes is eliminated.

Unlike previous inks, which require a liquid coagulation reservoir, the newly formulated inks are concentrated enough to rapidly solidify and maintain their shape in air, even as they span gaps in underlying layers.

This gives us the ability to start, stop and reposition the flow of ink repeatedly, providing
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