New cell-based sensors sniff out danger

Imagine this: A small, unmanned vehicle makes its
way down the road ahead of a military convoy. Suddenly it stops and relays a
warning to the convoy commander: The presence of a deadly improvised explosive
device, or IED, has been detected by sophisticated new sensor technology
incorporating living olfactory cells on microchips mounted on the unmanned
vehicle. The IED is safely dismantled and lives are saved. This scenario may
become a reality thanks to the work of three faculty researchers in the University of Maryland’s A.
James Clark School of Engineering who are collaborating across engineering
disciplines to make advanced “cell-based sensors-on-a-chip” technology
possible. Pamela Abshire, electrical and computer engineering (ECE) and
Institute for Systems Research (ISR); Benjamin Shapiro, aerospace engineering
and ISR; and Elisabeth Smela, mechanical engineering and ECE, are working on
new sensors which take advantage of the sensory capabilities of biological
cells. These tiny sensors, only a few millimeters in size, could speed up and
improve the detection of everything from explosive materials to biological
pathogens to spoiled food or impure water.

Today’s biochemical detectors are slow and produce
an unacceptable number of false readings. They are easily fooled because they
often cannot distinguish subtle differences between deadly pathogens and
harmless substances, and cannot fully monitor or interpret the different ways
these substances interact with biological systems. To solve this problem, the Clark School
researchers are learning how to incorporate real cells into tiny microsystems
to detect chemical and biological pathogens. Different cells can be grown on
these microchips, depending on the task at hand. As a bloodhound hot on the
trail of a scent, a chip containing a collection of olfactory cells plus
sensing circuits that can interpret their behavior could detect the presence of
explosives. The researchers plan to use other specialized cells much
like a canary in a coal mine. The cells would show stress or die when exposed
to certain pathogens, and the sensing circuits monitoring them would trigger a
warning — more quickly and accurately than in present systems. The researchers
are tackling the many challenges that must be met for such chips to become a
reality. Abshire, for example, is building circuits that can interact with the
cells and transmit alerts about their condition. Shapiro and Smela are working
on micro-fluidics technology to get the cells where they need to be on the
chip, and to keep them alive and healthy once they are in position. Smela is
also developing packages that incorporate the kind of wet, life-sustaining
environments the biological components need, while keeping the sensitive
electronic parts of the sensor dry.

Current research funding for the cell-based sensor
technology comes from the National Science Foundation (NSF), DHS, and the
Defense Intelligence Agency. Potential applications for their use extend well
beyond national security, however. For example, cell-based sensors could detect
the presence of harmful bacteria in ground beef or spinach, or detect the local
origin of specialty foods like cheeses or wines. In the pharmaceutical industry
they could identify the most promising medicines in advance of animal and human
trials, increasing cost-effectiveness and speed in developing new drugs. And
they could speed up research in basic science. Imagine tiny biology labs, each
one on a chip, in an array of thousands of chips that could fit in the palm of
your hand. Such arrays could advance biologists’ fundamental understanding
about the sense of smell or help doctors better see how the immune system
works. They could be placed on fish as they swim in the ocean to monitor water
quality, or set on a skyscraper’s roof to evaluate air pollution. “We
bring the capability to monitor many different cells in parallel on these
chips,” explains Abshire. “You could say we’re applying Moore’s Law
of exponentially increasing computer processing capability to cell
 biology.”

The research won the University of Maryland’s 2004
Invention of the Year Award in the physical science category. A patent
application is on file with the U.S. Patent and Trademark Office.