tweezers on the other hand are large and expensive devices.
Researchers at Penn State, however, have developed
acoustic tweezers that are smaller than a dime and can be
fabricated onto a chip using standard chip making techniques.
acoustic tweezers can be used to position many tiny objects like
cells simultaneously. The objects are placed equidistant from each
other either in parallel lines or on a grid. The most useful method
for biological applications would be the grid configuration. The
researchers say scientists could use this configuration to place stem
cells on a grid for testing or to place skin cells on a grid to grow
"Current methods for moving individual cells or
tiny beads include such devices as optical tweezers, which require a
lot of energy and could damage or even kill live cells," said
Tony Jun Huang, assistant professor of engineering science and
mechanics. "Acoustic tweezers are much smaller than optical
tweezers and use 500,000 times less energy."
saying, "Acoustic tweezers are not just useful in biology. They
can be used in physics, chemistry, and materials science to create
patterns of nanoparticles for coatings or to etch surfaces."
acoustic tweezers work by creating a standing surface acoustic wave.
If the two acoustic sound sources are aimed at each other, a series
of lines is formed where objects align. If aimed at right angles to
each other a line or series of lines are formed creating a
checkerboard effect. The tweezers are made by fabricating an
interdigital transducer onto a piezoelectric chip surface. These
transducers are the source of the sound. The researchers tested the
acoustic tweezers using cow red blood cells and a single E. coli
"The results verify the versatility of our
technique as the two groups of cells differ significantly in both
shape (spherical beads vs. rod-shaped E. coli) and size," Noted
"Most cells or particles patterned in a
few seconds," said Huang. "The energy used is very low and
the acoustic tweezers should not damage cells at all. Because they
have different properties, the acoustic tweezers could also separate
live from dead cells, or different types of particles."