| A Material World: | |
| Materials Processing | |
Georgia Tech chemical engineering researchers are developing an innovative new method for manufacturing microfluidic devices, also sometimes referred to as "labs-on-a-chip." These devices are small microchip-like structures that contain arrays of microchannels and other components that can be used to manipulate small (nanoliter to microliter) volumes of fluids.
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Although still early in its development, microfluidic technology is already affecting medical, environmental and chemical technologies. Examples include devices for chemical synthesis and drug discovery, medical testing and genetic diagnostics, and micro-chemical analysis and sensing.
In their work, research teams led by Drs. Sue Ann Bidstrup Allen, Cliff Henderson and Paul Kohl are devising a processing technology that could make profound improvements in the fabrication of microfluidic, microelectronic and microelectro-mechanical devices. The basis for this technology stems from the recent discovery that certain classes of polymeric materials (e.g., polynorbornenes) can be cleanly and thermally decomposed in-situ to form microchannels or air-gap structures in microelectronic materials.
One of the major advantages of this approach is its compatibility with current integrated-circuit fabrication processes. Thus, it holds the potential to conveniently make hybrid devices that are both microelectronic and microfluidic in function.
The researchers' long-term goal is to develop an inexpensive, mass-fabrication processing technology for microfluidic devices. The technology would be used to build complex, three-dimensional fluidic devices and to integrate such fluid-handling functions with more conventional microelectronic devices.
Technology also developing on the nanoscale is a rapid prototyping process for forming tiny three-dimensional shapes. The process allows scientists to build microscopic electronic or photonic prototype devices and structural materials through chemical vapor deposition (CVD).
Mechanical engineering researcher Dr. Jack Lackey and his colleagues have developed a new technique they call "laser-jet CVD rapid prototyping" or LCVD-RP. It involves a laser heating a particular spot on a substrate while a high-velocity jet sprays a reagent in gas form on the spot. The process triggers a CVD reaction that leaves a permanent coating derived from the reagent material. By moving the substrate relative to the laser and gas jet, researchers can build a 3-D structure layer by layer. Changing the type of reagent or using several jets at once allows for different materials, such as ceramics or metals, to be deposited simultaneously, thus producing composite structures.
One of the novel aspects of the Georgia Tech process is the use of a miniature gas-jet to deliver reagent directly to the substrate. The jet enhances the chemical kinetics of the CVD reaction, thus increasing the deposition rate. Layer thicknesses on the order of a few nanometers are possible, and because deposition occurs at the atomic level, the material is ultra-pure, mechanically sound and almost fully dense. In addition, the technique may be adapted for manufacturing.
Although this LCVD-RP system is operational, advances in other areas must occur before it can be used to fabricate novel devices and laminates. Those advances must come in process-structure-property interrelationships for LCVD deposits, rapid prototyping-process planning and micromechanics of laminated materials. Drs. David Rosen and Iwona Jasiuk are contributing their expertise in these areas.
— Gary Goettling
For more information, contact:
(1) Dr. Paul Kohl, School of Chemical Engineering, Georgia Tech, Atlanta, GA 30332-0100. (Telephone: 404-894-2893) (E-mail: paul.kohl@che.gatech.edu);
(2) Dr. Jack Lackey, School of Mechanical Engineering, Georgia Tech, Atlanta, GA 30332-0405. (Telephone: 404-894-0573) (E-mail: jack.lackey@me.gatech.edu)
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