Precision miniature peristaltic pump is at the core of a new
multi-platform hazardous materials detector. The ability to transfer tiny
samples, excellent repeatability and zero contamination risk make the
peristaltic format the right choice for this sophisticated field analyser
Watson-Marlow Alitea was already supplying biotechnology equipment
manufacturer, Biosensor Applications Sweden, when the latter invited the
company to help it with a new project that had considerable market
potential in the fields of explosives and drugs detection. The
Sweden-based subsidiary of peristaltic pump specialist, Watson-Marlow,
was asked to provide a pump solution for Biosensor's new Biosens-D
narcotics and explosive detection system, which is designed to work in
difficult, contaminated environments.
The key criteria were that the sample delivery be extremely accurate and
repeatable and that there were no chances of sample contamination
upstream of the detector. This specification was fulfilled by Alitea's
400F/A peristaltic pump - a matchbox sized unit that is capable of
precision dispensing at volumes down to one microlitre. But Alitea's
involvement didn't stop there. The company studied the application
requirements more deeply, including the flow rates expected, the amount
of space available for the pump and its mounting restrictions, as well as
its drive requirements. Biosensor was used to working with stepper
motors, so Alitea ensured that the units were supplied coupled to stepper
motors. The modular construction of the 400F/A, moreover, allowed
additional tailoring without incurring extra costs.
The pump transfers the test samples in a carrier fluid to a 'Biocell',
where it is made to vibrate at a high frequency. The carrier fluid
contains antibodies for the component being tested (heroin or TNT, for
example). If the substance is present, the antibody will be attracted to
it, causing a mass loss within the Biocell that changes its frequency of
oscillation. This frequency change is proportional to the size of the
detected sample. As the antibody is between 100 and 10,000 times heavier
than the target molecule, the frequency change is a very sensitive
measure of whether the sample being tested contains the target substance.
This ability to detect tiny traces in the field can save both time and
money. Instead of pulling out all of the boxes in a shipping container
and manually inspecting each one, a single sample of the air in the
container can be taken and used to give an indication of the presence of
a narcotic or explosive substance.