Page 190 - An Introduction to Microelectromechanical Systems Engineering

CHAPTER 6
MEMS Applications in Life Sciences

“Jim, you’ve got to let me go in there! Don’t leave him in the hands of Twentieth-
Century medicine.”
—Dr. Leonard McCoy speaking to Captain James Kirk,
in the movie Star Trek IV: The Voyage Home, 1986.

The “medical tricorder” in the famed Star Trek television series is a purely fictional
device for the remote scanning of biological functions in living organisms. The
device remains futuristic, but significant advances in biochemistry have made it pos-
sible to decipher the genetic code of living organisms. Today, dozens of companies
are involved in biochemical analysis at the microscale, with a concentration of them
involved in genomics, proteomics, and pharmacogenics. Their successes have
already had a positive impact on the health of the population; examples include
faster analysis of pathogens responsible for illness and of agricultural products as
well as more rapid sequencing of the human genome. Systems expected in the near
future will detect airborne pathogens responsible for illness (such as Legionnaire’s
disease or anthrax in a terrorist attack) with a portable unit, give on-demand genetic
diagnostics for the selection of drug therapies, be able to test for food pathogens
such as E. coli on site, and more rapidly test for bloodborne pathogens.
Conventional commercial instruments for biochemical and genetic analysis,
such as those available from Applied Biosystems of Foster City, California, perform
a broad range of analytical functions but are generally bulky. The concept of micro
total analysis system (µTAS), which aims to miniaturize all aspects of biochemical
analysis, with its commensurate benefits, was introduced in 1989 by Manz [1]. This
chapter begins with an introduction to microfluidics, followed by descriptions of
the state of the art of some of the microscale methods used in DNA analysis. Finally,
electrical probe techniques and some applications are presented. A common theme
will be the use of glass and plastic substrates, in contrast to most of the devices in
other chapters of this book.

Microfluidics for Biological Applications

The biological applications of MEMS (bio-MEMS) and microfluidics are inextrica-
bly linked because the majority of devices in systems for biological and medical
analysis work with samples in liquid form. Outside of biological analysis, microflu-
idics have applications in chemical analysis, drug synthesis, drug delivery, and
point-of-use synthesis of hazardous chemicals. In this section, we discuss common
pumping methods in bio-MEMS and the issue of mixing.

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