Biochips – fundamentals and applications - Electrochemical Sensors, Biosensors and Their Biomedical Applications - page 356

synthetic chemists, chemical engineers, biochemists, and biomedical engineers are now
becoming more and more interested in using new micro- and nanotechnological tech-
niques in this area.
The idea of LOC is to have a bank of specialized modules that can be fi tted together
like Lego building blocks to create a system, custom-tailored toward a specifi c applica-
tion. The LOC would combine tiny channels, pumps, and storage chambers with elec-
tronic and optical devices, actuators and sensors to perform multi-step tasks. These
systems, fabricated using technologies adopted from the microelectronics industry,
are enabling researchers from many disciplines to approach their activities in new
ways. The term LOC is now intimately linked with the other buzzwords of the new
micro-era: proteomics, genomics, combinatorial chemistry, drug discovery, ultra-high
throughput screening, massively parallel synthesis, and even bioinformatics.
Microfl uidics is the core technology that deals with the movement of small amounts
of fl uid. Subtechnologies would include electrophoresis, electrodynamics, semiconduc-
tor fabrication methods, labeling technology, laser fl uorometry, and inkjet printing. A
microfl uidic device can be identifi ed by the fact that it has one or more channels with
at least one dimension less than 1 mm. Microfl uidics can handle common fl uids such
as whole blood samples, bacterial cell suspensions, protein or antibody solutions and
various buffers; it is the key toward the development of microsynthesis, microsepara-
tions and lab-on-chips for sample preparation, rinsing, mixing, reaction, and other
fl uid processing needs for small volumes that cannot be performed in traditional ways.
It is expected that microfl uidics will revolutionize the fi elds of chemistry and biology
in many applications, such as proteomics and genomics research, high throughput and
small sample analysis, on-site fi eld and environmental analysis, clinical diagnostics,
small-quantity syntheses and reactions, combinatorial synthesis, and on-line analysis in
industrial processes. More detailed applications in a variety of interesting measurements
include molecular diffusion coeffi cients [141], pH [142], chemical binding coeffi cients
[141], and enzyme reaction kinetics [77, 143]. Other applications for microfl uidic
devices include capillary electrophoresis [144], isoelectric focusing [142, 145], immu-
noassays [146, 147], sample injection of proteins for analysis via mass spectrometry
[148, 149], PCR amplifi cation [150, 151], DNA analysis [152, 153], cell manipulation
[154], cell separation [155], cell patterning [156], and chemical gradient formation
[157, 158]. Many of these applications have utility for clinical diagnostics [159, 160].
The use of microfl uidic devices to conduct biomedical research and create clini-
cally useful technologies has a number of signifi cant advantages. Because of the small
volume, usually several nanoliters, the amount of reagents and analytes used is quite
small. This is especially signifi cant for expensive reagents. The microfl uidic technolo-
gies for such devices are relatively inexpensive and are very amenable both to highly
elaborate, multiplexed devices and also to mass production. One of the long-term goals
in the fi eld of microfl uidics is to create integrated, portable clinical diagnostic devices
for home and bedside use, thereby eliminating time-consuming laboratory analysis
procedures. Additional possible benefi ts of devices based on microfl uidics include
automation, reduced waste, improved precision and accuracy, and disposability.