3 Dimensional Molding Microbabrication
Miniaturizing chemical, biological, and medical devices and systems has many advantages,
including the use of small sample and reagent volumes, system portability, and disposability.
Although microfabrication of microfluidic devices is highly developed, there are still certain
limitations.
MicroDysis has developed a unique microfabrication technology – 3 dimensional molding (3DM)
to overcome the deficiencies of established approaches for microfluidic devices.
Most microfluidic devices are fabricated with silicon and glass using photolithography,
etching, and bonding. These methods are adopted from the conventional fabrication
techniques of the semiconductor industry. More recently, hot embossing has been used
for complex microfabricated structures. Current methods, though highly developed, have
some limitations and disadvantages for fluidic device fabrication and construction. For
example, bonding is an unavoidable processing step that is costly and prone to imperfections.
A common drawback with bonding is incomplete bonding of the areas and regions, which
causes microchannel, microchamber, or cavity imperfections, as well as cross leakage. As
a microstructure becomes more and more complex, this incomplete bonding becomes an
increasingly unwieldy problem. Varying the depths within the structure on a single wafer
is not possible in single step processing. These methods are expensive, as they require
clean room processing; photolithograph, etching, and bonding procedures; as well as a silicon,
glass, or quartz wafer material. Consequently, unit costs of the microfluidic devices are very
high. For some applications, truly 3 dimensional structures are desired, especially those that
possess arbitrary surface height profiles. Realization of such structures generally requires
multiple lithographic masking and etching, alignment and bonding steps, which add significant
process complexity and impact reproducibility and yield.
The 3DM technology for microstructure fabrication with liquid polymers or resins eliminates
the bonding procedure in traditional and other microfabrication methods. A device mold is
assembled with sacrificial mold components and functional components. A liquid polymer is
poured into the device mold. After the liquid polymer cures, the sacrificial mold components
are removed from the solid polymer so that channels and chambers with the complementary shapes
of the sacrificial mold components are created inside the device body and the functional
components are integrated.
There are a number of immediate advantages of the 3DM technology. These include the following:
• No fluidic Leakage: The microfluidic device is a non-bonded integral structure so there is
no fluidic leakage or crosstalk from or between the microstructures.
• Integration: The technology makes it easier to embed functional components with fluidic
channels and chambers, to create integration of electronics, optics, fluidics, and their
interfaces in the device, thus to facilitate the development of lab-on-a-chip devices.
• Lower Cost: Materials used in this approach are less expensive than the glass, silica,
and quartz used in other fabrications.