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University of Pennsylvania Student
Creates Electric Tweezers
The ability to sort cells or manipulate
microscopic particles could soon be in the hands of
small laboratories, high schools and amateur scientists,
thanks to researchers at the University of Pennsylvania
School of Engineering and Applied Science. They have
created a device, called "electric tweezers,"
which can manipulate and move almost any object seen
on a simple microscope slide.
The research was led by graduate student Brian Edwards,
with the help of his advisor Nader Engheta, professor,
and Stephane Evoy, adjunct assistant professor, both
of Penn's Electrical and Systems Engineering Department.
While devices with similar functionality using lasers
exist, they often cost upwards of a quarter-million
dollars. Edwards' device performs some of the same tasks
as laser tweezers, yet at a price anticipated to be
in the same range as a high-end desktop computer.
"The tweezers create an electric field that you
can use to manipulate almost any object on a microscopic
scale. It has the potential of being a powerful tool
for research," said Edwards, a doctoral candidate
in Penn's Electrical and Systems Engineering Department.
"I would prefer not to put a limit on the type
of tasks that can be done with it, but I hope it will
find uses in anything from picking an individual cell
out of a culture to fabricating circuits."
All it would take to use electric tweezers is a computer
and a microscope. The tweezers' action occurs on a common
glass microscope slide embedded with five electrodes.
These electrodes create an electric field that can be
used to push, pull, move and spin a selected object
in any direction without actual physical contact. Using
software Edwards developed, an operator can select an
individual object from a microscope image on a computer
screen.
The electronic tweezer
setup.
"Different types of particles respond
differently to different frequencies in the electric
field," Edwards said. "Once you lock onto
the object of interest you can move it however you like."
The electric tweezers take advantage of the phenomenon
known as dielectrophoresis, where electric fields impart
a force upon a neutral particle. In essence, the object
that is selected surfs atop the hills and valleys created
by subtly changing the electric field. The principle
works best on the microscopic scale, which makes it
ideal for this application.
"Moving objects with the tweezers is a lot like
playing one of those wooden labyrinth games, but, instead
of twisting knobs to move a ball in the maze, we're
adjusting an electric field to move a small object,"
Edwards said. "The tweezers move the object by
fiddling with the electric field. All the math is done
on the computer, so all the user needs to do is move
a joystick."
According to Edwards, the electrical field can be attuned
to almost anything visible through a microscope. He
believes the device will be a boon to smaller laboratories
that cannot afford similar devices, as well as to high
schools and science hobbyists. Its size, utility and
potentially low price could put it into the hands of
almost anyone interested in experimenting with the technology.
"We hope that the electric tweezers could mean
to science what the PC meant to computing; it's a scientific
tool for the rest of us," said Hugo FitzGerald
nanotechnology and licensing manager at Penn's Center
for Technology Transfer.
The Center is assisting Edwards in patenting and, along
with the Bressler Group, bringing electric tweezers
to the marketplace.
Visit www.upenn.edu
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