Momentum - The Magazine for Virginia Tech Mechanical Engineering Vol. 1 No. 3 | Page 21

New nano fabrication method creates
structures up to 1 million times faster
A process for creating micro and nano-structures
on three dimensional (3D) objects holds great promise to usher in new nano-enabled applications in
advanced materials and biotechnology.
The work, published in the journal Nanoscale in
July, drastically reduces costs while speeding the
production process by four to six orders of magnitude,
compared to current state of the art techniques, according to Virginia Tech Mechanical Engineering doctoral student Zhou Ye, his advisor, Associate Professor
Bahareh Behkam, and their collaborator, Associate
Professor Amrinder Nain.
Their process called Spun-Wrapped Aligned Nanofiber (SWAN) lithography, can fabricate micro- and
nano-structures on the entire surface of any 3D object
by applying polymer fibers, about 500 times smaller than the diameter of human hair, over an object,
followed by etching areas of the object not covered
by the fiber, and then removing the fiber itself, thus
resulting in nano-textured gold surface. Gold film
is widely used in biosensing applications due to its
non-reactive and conductive nature. With SWAN
lithography’s ability to pattern the entire 3D object
independent of curvature, the sensing area along with
the signal to noise ratio are substantially increased.
The process works on all 3D objects irrespective of
their geometry, thereby overcoming a major limitation of current methods which work only on simple
geometries (such as cylindrical objects) or flat surfaces.
In addition to its ability to pattern complex-shaped
objects, SWAN lithography also has three additional
characteristics that, in the words of Behkam, “make
the potential for the process, expansive.” The first is
that SWAN lithography can be applied to wide variety
of object shapes of varying curvatures, and be done
at both micro- and nano-scales, something electron
beam lithography (EBL) and focused ion beam milling (FIB) can’t do,” Behkam said. “Second, we have
reduced the costs considerably; and finally, the time
it takes to texturize an object is orders of magnitude

faster compared to other methods.” Behkam contends the current commercially available systems for
creating nano structures typically take 10,000 to 1
million times as long. That means what SWAN lithography can do in one minute, the others would spend
166 hours or 694 days to accomplish.
With cost, utility and speed issues solved, the obvious question remains as to what SWAN lithography
cannot achieve?
“Really, it allows us to explore a large variety of
application areas. We are especially interested in
health care-related technologies,” Behkam said. “We
are working to engineer nano components that work
with biologic components. For example, in implantable medical devices, microbial infections are not only
associated with increased mortality but are also significant contributors to the emergence of antibiotic resistance traits. With increased life expectancy, we are
likely to see an increase in the use of short and longterm implantable biomedical devices. This represents
a growing unmet medical need to counter microbial
biofilm-associated infections. Current treatment for
biofilm-associated infections typically involve a combination of surgical replacement of the implant, and
long-term antibiotic therapy, which incurs high health
care costs and remains controversial because compelling evidence of their effectiveness is lacking. SWAN
lithography enables engineering of micro/nano-scale
topological cues on the surface of medical implants
to mitigate biofilm formation, allowing a far superior
function and safety.”
In addition to medical applications, the SWAN
lithography process also allows functionality to be
built into other products, including nano sensors for
photonic and plasmonic applications.
Currently, Behkam and her team are speaking with
industry to further develop the patent-pending technology and bring it to the next step for wide-scale use
in everything from camera lenses and aircraft wings,
to ship hulls, solar panels, and biomedical devices and
implants.

Article - Rosaire Bushey