By Will Soutter
Topics Covered
Introduction
Microfluidics and
Nanofluidics
Role of Nanotechnology
Life Science Applications
Conclusions
References
Introduction
Lab-on-a-chip refers to technologies which allow operations which
normally require a laboratory -synthesis and analysis of chemicals - on
a very miniaturized scale, within a portable or handheld device.
There are many benefits to operating on this scale. Analysis of
samples can take place in situ, exactly where the samples are
generated, rather than being transported around to a large laboratory
facility. The differences in fluid dynamics on a very small scale mean
that it is easier to control the movement and interaction of samples,
making reactions much more efficient, and reducing chemical waste.
The main challenge to development of lab-on-a-chip devices is the
design and fabrication of devices on a very small scale which are
functional and cost-effective. In recent years, advances in materials,
and in micro- and nanofabrication techniques, have allowed a number of
lab-on-a-chip type devices to be built and tested.
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Figure 1. Schematic of the
"Genotyper" device, developed by researchers at the University of
Michigan, which could identify different strains of flu. Image credit:
Dr Ronald Larson, via NIAID.
Microfluidics and
Nanofluidics
Lab-on-a-chip integrates many different areas of technology. The one
which ties them altogether and makes the whole concept possible,
however, is microfluidics and nanofluidics.
Microfluidics is defined as the manipulation of the flow of very
small quantities of fluid within channels in the micrometre range -
nanofluidics takes this a stage further, and often deals with the
movements of individual macromolecules in solution. Understanding and
commercializing this area of physics has been crucial to development of
viable lab-on-a-chip devices.
The discipline of microfluidics developed as a consequence of
increasingly accurate analysis techniques such as high-performance
liquid chromatography (HPLC) and capillary electrophoresis (CE), which
are able to obtain extremely accurate results from a small sample size.
As the capabilities of these techniques progressed, it was a natural
step to try and perform them in as compact a form factor as possible.
Role of Nanotechnology
Certain developments in the field of nanotechnology have been
crucial to enabling lab-on-a-chip technologies. In particular,
lithography, which has been used to create nano-scale features on metal
and semiconductor surfaces, has been adapted to create tiny,
micro-scale pumps, valves and other components for manipulating flow
from polydimethylsiloxane (PDMS). PDMS is a transparent, flexible
elastomer, which is better suited to rapid prototyping and allowing
optical tests in microfluidic systems than traditional lithography
materials.
Nanosensors are also a key element of many lab-on-a-chip systems.
Sensors have been developed using nanomaterials like carbon nanotubes,
capable of detecting very low concentrations, even down to single
molecules in some cases. These are extremely useful in allowing a high
degree of analytical flexibility in a lab-on-a-chip system without
increasing the overall size of the device.
Life Science Applications
Whilst there are applications for lab-on-a-chip systems for
small-scale, rapid synthesis and analysis in the chemical industry, the
majority of research to date has focused on diagnostic devices for use
in GP's offices or at sites without access to full laboratory
facilities.
Medical and life science applications which have been explored
include DNA or RNA sequencing, and examination of protein
crystallization to screen for conditions. Sample sizes can be just a
single cell or even smaller. Rapid, bespoke synthesis of
radioactively-labelled compounds for techniques like positron emission
tomography (PET) has also been investigated.
Conclusions
Future advancements in lab-on-a-chip technology will always depend
on at least two major scientific disciplines - microfluidics, and
molecular biology. Nanotechnology will play a key role in tying these
two fields together as the technology progresses.
Despite the hurdles always associated with commercialization of a
new technology, viable examples of these devices are beginning to
appear on the market. It seems that lab-on-a-chip technology will
become increasingly important in the coming years, both in the medical
world and in the chemical industry.
References