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Lab-on-a-chip detects ammonia in human breath
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A
lab-on-a-chip that is sensitive enough to detect just
a of ammonia in human breath has been developed by Björn
Timmer of University of Twente in The Netherlands. Ammonia
is an indicator for the development of a bacterial infection
in the stomach. The tiny dimensions of this lab-on-a-chip
have several advantages: it just needs a tiny sample,
it is fast, and a compact handheld analyzer can be built.
Timmer has finished his PhD research on this system
within MESA+ research institute, on May 28.
The concentration of ammonia in human breath provides
the doctor with information about the presence of the
bacterium Helicobacter Pyloris in the stomach. This
could lead to an ulcer. The bactery disturbs the ureum
household in the body, and this change can be detected.
The present methods involve drinking some radioactive
CO2, forming the marker for the bacterium. This is quite
expensive and available at a limited number of hospitals.
An alternative should be fast, very sensitive and relatively
cheap.
The ammonia detectors available, e.g. for environmental
monitoring are in fact too large and slow; apart from
that they need quite a volume to do the analysis. Miniaturization
is the key word there. Timmer has combined all the necessary
components on one single chip. This reduces the detection
time from twenty minutes to about one minute, and a
100 times smaller sample will suffice.
For this, components of the detected gas are mixed with
fluid and subsequently they are separated. The electrical
conductivity of the separate fluid channels will be
different, and by measuring this the concentration of
ammonia can be deduced. The system is sensible enough
for breath analysis. And selective enough, as well:
as breath has a higher concentration of carbon dioxide
than air, the selectivity of the system must be high.
Björn Timmer did his research within the BIOS Lab-on-a-chip
Group of prof. Albert van den Berg. This group is part
of the MESA+ Institute for Nanotechnology of the University
of Twente.
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http://www.bios.el.utwente.nl
Dhr.
Wiebe van der Veen
University of Twente, Holland
w.r.vanderveen@utwente.nl
Tel: +31534894244 |
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