A miniaturized ultrasonic device capable of capturing and moving single cells and tiny living creatures is compared to a U.S. dime. Imaget: Xiaoyun Ding, Stephen J. Benkovic, and Tony Jun Huang—Penn State |
A team of bioengineers and biochemists from Penn State
University has
demonstrated a device about the size of a dime that is capable of manipulating
objects, including living materials such as blood cells and entire small
organisms, using sound waves. Their research is published online in the Proceedings of the National Academy of
Sciences (PNAS).
The device, called acoustic tweezers, is the
first technology capable of touchlessly trapping and manipulating Caenorhabditis elegans (C. elegans), a one millimeter long
roundworm that is an important model system for studying diseases and
development in humans. Acoustic tweezers are also capable of precisely
manipulating cellular-scale objects that are essential to many areas of
fundamental biomedical research.
Acoustic tweezers use ultrasound, the same
noninvasive technology doctors use to capture images of the fetus in the womb.
The device is based on a piezoelectric material that produces mechanical motion
when an electrical current is applied. The vibrations pass through transducers
attached to the piezoelectric substrate where they are converted into standing
surface acoustic waves (SAWs). The SAWs create pressure fields in the liquid
medium that hold the specimen. The simple electronics in the device can tune
the SAWs to precisely and noninvasively hold and move the specimen or inorganic
object.
“We believe the device can be easily
manufactured at a cost far lower than say, optical tweezers, which use lasers
to manipulate single particles,” says Penn State
associate professor of bioengineering Tony Jun Huang, whose group pioneered
acoustic tweezers. “Optical tweezers require power densities 10,000,000
times greater than our acoustic tweezers, and the lasers can heat up and damage
the cells, unlike ultrasound.”
For many biological systems, acoustic
tweezers will provide an excellent tool to mimic the conditions inside the body
where cells are subject to waves of pressure and pulses of chemicals. According
to Stephen Benkovic, Evan Pugh professor of chemistry and holder of the Eberly
family chair in chemistry at Penn
State, whose group
contributed to the paper, “Acoustic tweezers will be used to position
cells for interrogation by pulses of drug-like molecules to test as well as to
exert mechanical forces on the cell wall. The cells will contain bio-chemical
markers, so we can observe the effect of drug pulses or pressure on the cell’s
biochemistry.”
Acoustic tweezers are very
versatile, says Huang. “We can manipulate a single cell or we can
manipulate tens of thousands of cells at the same time.” Currently, the
size of objects that can be moved with acoustic tweezers ranges from
micrometers to millimeters, although with higher frequencies, it should be
possible to move objects in the nanoscale regime, they believe. Further work
will include modifying the device to accommodate more fundamental biomedical
studies with the Benkovic group. Ultimately, the patent-pending technology
could lead to compact, noninvasive, and inexpensive point-of-care applications,
such as blood cell and cancer cell sorting and diagnostics. For now, the
ability to trap and manipulate a living C.
elegans for study is proof of their device’s potential utility.
Source: Penn State University