3-D Chemistry Builds Complex Micro-Structures

Try it for complex structures that would be difficult to build layer-by-layer with 2-D lithographic processes.

"We believe this technique provides a real competitive advantage for making complicated 3-D microstructures." That's Georgia Institute of Technology Researcher Seth Marder describing what he terms "a disruptive platform technology that we believe will provide broad new capabilities." Marder, also a professor at Georgia Tech's School of Chemistry and Biochemistry, says the technique could compete with existing processes for fabricating many microfluidic devices. He also cites such things as photonic bandgap structures, optical storage devices, photonic switches and couplers, sensors, actuators, micromachines -- even scaffolds for growing living tissues. The unique 3-D microfabrication technique uses a special class of light-activated molecules to selectively initiate chemical reactions with polymer and other materials. The result: complex structures with sub-micron features. Also demonstrated: the fabrication of tiny silver wires from patterns written in materials containing silver nanoparticles and ions. The researchers believe that for 3-D microstructures, the simple two-photon technique could compete with complex multi-step fabrication processes that use lithography, etching and layering technologies borrowed from the microelectronics industry. However, at the moment, the two-photon technique can produce only one structure at a time, while microelectronics-based processes simultaneously generate hundreds or thousands of identical structures. Right now, that makes the new system more suitable for adding specialized 3-D structures to microsystems, prototyping new structures or making molds than for producing entire systems, notes researcher Joseph Perry, also a professor in the School of Chemistry and Biochemistry. Producing each structure now requires about 25 seconds, but increases in speed could make mass production feasible. "We are working to integrate the technologies and develop a system that should be able to operate at a thousand times the throughput of the current system," he adds. "A single 3-D fabrication system should be able to generate about a million individual device structures per day. With a production facility using a number of fabrication systems, there is potential for certain types of mass production." The researchers envision tabletop fabrication machines that would use a computer-generated design system to laser write the desired structure. A cartridge containing the polymer film would then be removed for chemical development.

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