Microassembler for building micromachines
3 April 2007
University of Illinois engineers have created a micro
device that uses agile, human-like fingers that can assemble micromachines
made of micron-sized parts. The device has potential to be refined to
manipulate parts and components for machines at the nano scale.
microscopic-sized machines assembled with micrometer or nanometer-scale
parts will need to be made with devices that use tiny, agile "fingers" that
can grip, lift and do the assembly work in a controlled, coordinated way.
Engineers at the University of Illinois at Chicago have developed and
demonstrated a one-square centimetre device they call the "micromanipulator
station" that accomplishes this goal.
"We think this will be useful in the microfactories of the future," said
Laxman Saggere, assistant professor of mechanical and industrial
He and graduate student Sandeep Krishnan describe their device in the March
issue of the Journal of Micromechanics and Microengineering.
Within their tiny chip-like station, four micro "fingers" can grasp and move
micron-sized particles as commanded. Micro tweezer-like devices now
commercially available can only grip and hold small particles in place, but
to manipulate them requires accessory devices that make the process
cumbersome. The UIC engineers got around this problem.
"We thought of mimicking the functionality of human fingers," said Saggere.
"The device has multiple, coordinated fingers that grip a particle and take
it from one given position to another within a small area."
Saggere and Krishnan have proved this works, using a laboratory device they
built. The prototype is proof of the concept, but refinements are planned.
"We can increase the number of fingers, increase the area in which
manipulation can occur, or enable more dexterous positioning of even smaller
particles by improving the fingertip design," he said. "We can also add a
little more flexibility and reduce the footprint size of the device in an
Making the fingers flexible and dexterous enough to do precise work at the
micro-scale level has yet to be accomplished. Saggere and Krishnan developed
systematic algorithms to design the configuration of the flexible fingers in
the micromanipulator to coordinate with each other like human fingers at the
micro- or even nanometer scale.
"We've verified our design algorithms. We've grabbed tiny microspheres —
diameters of 15 microns — using these fingertips to push it from one
location to another, but exact positioning is not yet possible," Saggere
said. "It's the first time that use of coordinated fingers has been
demonstrated, but there's a lot more to accomplish."
A micron is a millionth of a meter, or 39 millionths (.000039) of an inch. A
grain of table salt measures about 60 microns on a side. A nanometer is
1,000 times smaller than a micron.
The engineers said future designs will likely employ piezoelectric actuators
to refine the sophistication of finger movement. They are also looking into
methods of overcoming certain adhesion forces that are predominant at the
micro scale and cause problems in releasing these ultra-small particles from
the fingers after manipulation.
While it may be years before micromanipulator stations go to work on a
commercial basis, Saggere and Krishnan's prototype holds promise for
creation of micro-scale machines that are only concepts today.
"Currently, a major limiting factor in development of micro-scale machines
is the assembly process," Saggere said. "Manual assembly is prohibitively
expensive, and the required precision, operator stress and eye strain
associated with assembling such minute parts under a microscope make it
impractical. If we want to make a micro-motor, we need to assemble it with
micro-gears, shafts and other components at micro scale. We can't do that
The future generation micromanipulator station may also prove useful in
mechanically manipulating and patterning biological cells to better
understand how they communicate, which could help in understanding diseases
and lead to better drug development.