FRONTLINE - College of Engineering - North Carolina State University

design a modeling process that is highly specific. Using molec-
ular modeling and computer-aided molecular design, we can
manipulate the material properties to optimize performance.”
Currently the team is working to design and produce micro-
needles with a variety of specifications and modeling the pen-
etration of the needles in skin to improve geometry and design.
The designs are being tested and validated in the Biomechanics
Laboratory at NC State with the help of Dr. Peter Mente, assis-
tant professor of biomedical engineering.
“The conventional microneedles are not mass producible,”
says Narayan. “What we are able to do is produce needles with
unique geometrics tailored with optimal skin penetration and
fracture resistance properties. Our goal is to be able to custom-
ize and mass-produce these microneedles. Dr. Lee’s modeling
work will help us find the most efficient and effective way to
manufacture the devices using this new laser technique.”
In the 2PIP process, laser pulses are delivered in femtosecond
(one millionth of a nanosecond) pulses to break chemical
bonds on photoinitiator molecules. These molecules react
with the Ormocer® monomers to create radicalized polymol-
ecules. (Monomers are single molecules that have the ability to
combine with similar molecules in a process called polymeriza-
tion.) The lasers are manipulated in three dimensions using a
micropositioning system to create a three-dimensional micro-
structure such as a microneedle. This new process opens the
doors for the development of nano and micro devices that will
have a wide variety of applications from painless injections to
orthopedic, prosthetic and cardiovascular devices.
“What initially attracted me to this type of research is the pos-
sibility that we may someday have tiny machines that can func-
tion within the human body to repair and heal the body,” said
Lee. “There is beauty in the machine that can do what your
hands cannot do and see what your eyes cannot see. This is the
direction I see that engineering should go.”
Lee’s vision of a micromachine that heals or helps the
human body may not be that far-fetched. He and Narayan
already envision that their modeling and fabrication
process may one day develop a tiny device that can reside
in the body of a diabetic and not only monitor blood
sugar levels but also deliver proper doses of insulin. The
device would combine the microneedles they are currently
designing with a microelectromechanical system (MEMS)
and a nanosensor that remains viable in the human body.
Essentially the diabetic would no longer have to prick a
finger, inject insulin or wear an external insulin pump.
Materials with antimicrobial properties may be incorpo-
rated so that the risk of infection, a serious concern for dia-
betics, would be all but eliminated.
“The tiny system that can go inside the body and make
repairs will probably not be developed in my lifetime,” says
Lee. “But it is satisfying to know that we are working in that
direction.” �
The two photon induced polymerization
(2PIP) process can
produce these microneedles
(left and below) using Ormocer ® .
(Images: courtesy Roger Narayan)
1