Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

3D fabrication technique uses light-activated molecules to create complex microstructures

16.02.2004


A three-dimensional microfabrication technique that uses a unique class of light-activated molecules to selectively initiate chemical reactions within polymers and other materials could provide an efficient way to produce complex structures with sub-micron features.


Georgia Institute of Technology Professors Seth Marder (left) and Joe Perry pose with laser equipment they use to write complex 3D structures in polymers and other materials.



Known as "two-photon 3D lithography," the technique could compete with existing processes for fabricating microfluidic devices, photonic bandgap structures, optical storage devices, photonic switches and couplers, sensors, actuators, micromachines -- and even scaffolds for growing living tissue.

Georgia Institute of Technology Researchers Seth Marder and Joseph Perry will describe the technique February 15 at the annual meeting of the American Association for the Advancement of Science (AAAS).


"We have developed a disruptive platform technology that we believe will provide broad new capabilities," said Marder, a professor in Georgia Tech’s School of Chemistry and Biochemistry. "We believe this technique provides a real competitive advantage for making complicated three-dimensional microstructures."

The technique uses a family of organic dye molecules known as Bis-donor phenylene vinylenes that have a special ability to absorb two photons of light simultaneously. Once excited, the molecules transfer an electron to form a simple acid or a radical group that can initiate a chemical reaction -- such as polymer cross-linking or ion reduction.

By adding small concentrations (0.1 percent) of the molecules to a resin slab containing cross-linkable acrylate monomer, for example, researchers can use a focused near-infrared laser beam to draw patterns and initiate cross-linking reactions only in material exposed to the light. The reactions can make that portion of the slab insoluble, allowing the remainder to be washed away to leave a complex three-dimensional structure.

The researchers have demonstrated the ability to create both positive and negative resists using two-photon activated reactions to alternatively create soluble or insoluble 3D patterns. Beyond polymers, Perry and Marder have demonstrated the fabrication of tiny silver wires from patterns written in materials containing silver nanoparticles and ions.

The molecules developed by Marder and Perry are hundreds of times more efficient at absorbing two photons than previous photoactive materials. That efficiency allows them to write 3D patterns in polymer slabs that are typically 100 microns thick, at light intensities low enough to avoid damaging the materials.

The laser writing process takes advantage of the fact that the chemical reaction occurs only where molecules have absorbed two photons. Since the rate of two-photon absorption drops off rapidly with distance from the laser’s focal point, only molecules at the focal point receive enough light to absorb two photons.

"We can define with a very high degree of precision in the x, y and z coordinates where we are getting excitation," Marder explained. "Using 700-nanometer light, the patterning precision can be about 200 nm across by 800 nm in depth."

By scanning the laser in the sample while turning the laser off and on, Perry’s group has created a variety of structures, including objects with moving parts like gears and chains. Three-dimensional structures produced by the technique could be used as molds or templates for mass-producing other structures through simple stamping processes. The technique could also be used to create textured surfaces on which tissues can be grown, or optical elements such as photonic band-gap structures used to manipulate light.

For producing 3D 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, the two-photon technique can produce only one structure at a time, while the microelectronics-based processes simultaneously generate hundreds or thousands of identical structures.

Right now, that makes the new system more suitable for adding specialized 3D structures to microsystems, prototypying new structures or making molds than for producing entire systems, notes Perry, also a professor in Georgia Tech’s 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 said. "A single 3D 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 structures. A cartridge containing the polymer film would then be removed for chemical development.

To move their technologies into the commercial world, Marder and Perry have helped form a company known as Focal Point Microsystems. The firm has licensed the technologies, which were developed when the scientists worked at the California Institute of Technology and the University of Arizona before joining Georgia Tech last summer.

In collaboration with researchers at Arizona and Cornell, Marder and Perry have also been examining the fluorescent properties of the materials for possible applications in biological imaging. The molecules also have properties that are of interest for photodynamic therapy, which would use light to destroy cancer cells.

For the future, Marder and Perry hope to continue improving their dyes, increasing the resolution of the laser writing process, expanding their family of materials – and better understanding the process. "The scientific challenges are getting things smaller, writing faster and increasing the number of materials in which you can write," Perry said.


###
The research has been supported by the National Science Foundation, National Institutes of Health, the Air Force Office of Scientific Research, Office of Naval Research and Defense Advanced Research Projects Agency.

Technical Contacts:
Seth Marder 404-385-6048; E-mail: seth.marder@chemistry.gatech.edu or
Joe Perry 404-385-6046; E-mail: joe.perry@chemistry.gatech.edu.

John Toon | EurekAlert!
Further information:
http://gtresearchnews.gatech.edu/

More articles from Process Engineering:

nachricht Etching Microstructures with Lasers
25.10.2016 | Fraunhofer-Institut für Lasertechnik ILT

nachricht Applying electron beams to 3-D objects
23.09.2016 | Fraunhofer-Institut für Organische Elektronik, Elektronenstrahl- und Plasmatechnik FEP

All articles from Process Engineering >>>

The most recent press releases about innovation >>>

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

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>