14 Jun 2005
An IR spectroscopy-based device developed in Switzerland could help speed up the diagnosis of disease.
Screening for diseases such as cirrhosis or hepatitis could be as simple as breathing into a tube thanks to the work of scientists at The Swiss Federal Institute of Technology (ETH). The Zurich-based team has devised apparatus that uses infrared (IR) laser spectroscopy to measure the amount of methylamines in human breath.
The proven link between the number of these large molecules in human breath and a range of illnesses forms the basis behind the group's non-invasive diagnostic tool.
By developing a narrow-bandwidth mid-infrared source, tunable between 2580 and 2870 cm-1, the researchers can target specific methylamine absorption lines that sit in the gap between CO2 and H20 spectra.
The team uses difference frequency generation in periodically poled lithium niobate (PPLN) to deliver 10 µW of IR emission tunable between 3.48 and 3.88 µm. Fed by a diode-pumped Nd:YAG laser and a near-infrared external cavity diode laser, the PPLN crystal source enables methylamine detection down to 250 ppb.
“Our goal is to achieve 1 ppb detection, which would give instantaneous breath analysis,” researcher Dilyan Marinov told Optics.org. “We could use fiber amplifiers for example to increase the power of the laser beam.”
Halfway through their three year project, the scientists are busy optimizing the technique in the lab in advance of field-testing that is scheduled to begin shortly at a hospital in Zurich. Currently, the team has to concentrate breath samples, which complicates the procedure and could potentially slow down diagnosis.
This research was presented at CLEO-Europe, part of the World of Photonics Congress co-located with Laser 2005. World of Photonics.