Technology Research News
The '60s sci-fi movie "Fantastic Voyage"
featured a team of scientists who were reduced to microscopic proportions
along with their submarine and injected into the bloodstream of a man
in a coma.
While the notion of shrinking living beings and complicated machinery
remains as fanciful as ever, the idea of getting up close and personal
with individual cells inside a living human is firmly within the realm
of the technologically possible.
Researchers at the University of California at Berkeley are building a
confocal microscope on a chip with the aim of giving physicians and scientists
the means to observe the inner workings of cells in their native habitats.
Confocal microscopes are tabletop instruments that cost several hundred
thousand dollars. They are used to record images of individual cells and
cellular components, often from living samples.
The researchers' confocal microscope will be slightly larger than the
ball in a ballpoint pen.
"Nanoscopic biophotonic imaging systems can change the... field of quantitative
biology," said Luke P. Lee, an assistant professor of bioengineering at
the University of with California at Berkeley. The devices could also
be used in home diagnostic biochips, and they could eventually serve as
vision systems for microrobots, said Lee.
Confocal microscopes focus reflected or fluorescent light from a small
spot in a sample through one or more lenses to a pinhole. A sensor on
the other side of the pinhole records the light coming through. The pinhole
blocks out-of-focus light so the microscope captures focused images of
small sections of the sample. Moving the lenses or the sample or bouncing
the light off movable mirrors produces a scan, or series of images, of
the whole sample.
A key advantage of the researchers' design is that the light source shines
directly through the lenses, which allows for a more compact device. The
lenses move to produce the scan.
The researchers plan to build an array of three-lens confocal microscopes,
each measuring one cubic millimeter, according to Lee. Each microscope
will be able to capture three-dimensional images. The Micro Confocal Imaging
Array will be "cheap, small [and] mass producible," he said.
The array could be integrated with microfluidic systems to form labs-on-a-chip
that channel biological fluids like blood into position under the microscopes,
according to Lee. The array could also be built on the tips of endoscopes,
which are probes that can be inserted into the body, in order to capture
images of cells at work.
So far, the researchers have built scanners consisting of two lenses and
actuators that move them. The lenses are formed by placing a drop
of liquid plastic in a ring about half a millimeter in diameter and hardening
the plastic with ultraviolet light. The actuators that move the lenses
are microelectromechanical systems (MEMS), which are made using computer
chip manufacturing processes.
The lenses work with visible light, and the researchers plan to expand
their range to ultraviolet and near infrared, said Lee. The researchers'
next step is integrating the lenses and actuators with microlasers and
detectors, said Lee. The Micro Confocal Imaging Array could be in use
in two to five years, he said.
The researchers' work "is a first step towards a chip-scale confocal microscope,"
said Ming C. Wu, a professor of electrical engineering at the University
of California at Los Angeles. "Miniaturization is important to integrate
[microscopes] with lab-on-a-chip type devices," he said.
The Berkeley device compares favorably to other miniature confocal microscopes,
said Wu. "Theirs uses scanning lenses, and is a transmission device, which
is more compact than reflection devices," he said.
Lee's research colleagues was Sunghoon Kwon. They presented the research
at the IEEE International MEMS 2002 Conference in Las Vegas in January.
The research was funded by the Defense Advanced Research Projects Agency
Timeline: 2-5 years
TRN Categories: Biotechnology; Data Acquisition; Microelectromechanical
Story Type: News
Related Elements: Technical paper, "Stacked Two Dimensional
Micro-Lens Scanner for Micro Confocal Imaging Array," IEEE International
MEMS 2002 Conference, Las Vegas, January 20-24, 2002
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