 
New
UC Berkeley "bionic chip" features living biological
cell successfully merged with electronic circuitry
25
Feb 2000
By
Kathleen Scalise, Public Affairs
BERKELEY--
On Friday, Feb. 25, researchers at the University of California,
Berkeley, will announce the successful invention of what they
believe is the first "bionic chip" - part living tissue,
part machine - in which a biological cell is part of the actual
electronic circuitry.
The
new UC Berkeley chip gives scientists something they long have
sought: an "open sesame" tool to get safely inside
fragile, living cells at the touch of a button.
The
first report of the technology will be published in the February
issue of the journal Biomedical Microdevices. UC Berkeley applied
for a patent on the technology last summer and is in the process
of licensing it commercially.
"It's
a key discovery because it's the first step to building complex
circuitry that incorporates the living cell," said UC Berkeley
mechanical engineering professor Boris Rubinsky, who created
the device with graduate student Yong Huang. Such chips and
the elaborate bionic circuitry they might make possible could
be useful for developing body implants for treatment of genetic
diseases.
The
new chip uses the discovery that a biological cell can act in
a circuit as an electrical diode, or switch, that allows current
to flow through the device at certain voltages.
Said
Rubinsky, "It works this way: the biological cell does
not transfer any current until a particular voltage is reached.
At that point, when the right voltage is attained, pores open
in the cell membrane and current starts to flow through the
cell."
The
particular voltage necessary to trigger the cell diode is different
for each type of cell. The new bionic chip automatically determines
the right voltage and, once known, "it's like having the
remote control to a door," he said. "This is important
because the door to the living cell has been very important
but very difficult for us to open reliably until now without
causing any damage to the tissue."
Cell
membranes allow certain materials in and keep others out depending
on the needs of the cell. The bionic chip can open and close
a cell membrane in milliseconds, allowing for a very precise
control never before possible. Once in place in the circuit,
the cells themselves are considered bionic since they can be
operated in this way by computer control.
"We
can introduce DNA, extract proteins, administer medicines -
all without bothering other kinds of cells that might be around,"
Rubinsky said.
Living
tissue has long been known to pass current, he said, but until
now, no one knew it could sit on an electronic chip and act
as a diode.
"In
the past, any electricity applied to the cell was like hitting
it with a hammer in the hopes that something would happen or
it would open for us. Now, we know just how to make it work,"
Rubinsky said.
UC
Berkeley's bionic chip took three years to build using silicon
microfabrication technology. It is transparent, so it can be
studied by microscope, and measures about one hundredth of an
inch across. The much tinier cell, which measures about 20 microns
across, or one thousandth of an inch, is not visible to the
naked eye. It sits in a hole in the center of the chip and is
kept alive with an infusion of nutrients.
Applications
for the bionic chip are varied and potentially include new ways
to treat genetic diseases such as cystic fibrosis or diabetes,
safer methods to test new pharmaceuticals for side effects and
more complex bionic electronic circuitry.
"The
first electronic diode made it possible to have the computer,"
Rubinsky said. "Who knows what the first biological diode
will make possible?"
He
said first commercial applications could begin within the year.
The
work was funded by a UC Berkeley Chancellor's Professorship
award. It is an example of the type of research the UC Berkeley
campus is now sponsoring through its new Health Sciences Initiative,
an effort that draws scientists from both the physical and biological
sciences into a multidisciplinary search for solutions to today's
major health problems.
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