IOP Project

Compact laser and photo acoustic cell enable handheld trace-gas detector

Projectnumber: IPD083385
Contact: M. Pollnau
Phone: +31 (0)53 489 10 37

More and more often, hospitals use devices that detect trace amounts of certain gases in human exhalation. The presence of a certain gas may indicate a condition like, for instance, lung cancer or kidney failure. The advantage of this method is that it is noninvasive. But the devices are expensive and bulky, says prof. dr. Markus Pollnau of the Integrated Optical Microsystems research group of Twente University: “We are going to develop a detector for ammonia (NH3) that’s smaller and more sensitive than existing detectors.”


The detector that Pollnau and his co-workers are developing, has two important components. Pollnau: “First, there is the solid state laser. It uses a crystal doped with Thulium or Holmium and produces a laser with a wavelength of 2 μm.” NH3 absorbs light at this wavelength, which means that the gas heats up and expands. The second major component is the photo-acoustic cell that takes care of the actual detection. Pollnau: “This cell is a small acoustic cavity that contains the gas. If this gas expands, a resonance obtains. By measuring this resonance, we can determine the concentration of the gas.” The laser will be integrated on a chip and its light will be coupled to the photo-acoustic cell by optical waveguide technology.


Once there is a prototype, clinical trials will determine how suitable the detector is as a diagnostic tool. Pollnau: “We’ll start testing it with known trace-gas concentrations, then we will continue with clinical trials on patients.” Whether the device will be successful, depends on several factors, like the price and the detection efficiency. Pollnau: “But even if we don’t have a device that’s ready to market, we will generate a great amount of knowledge concerning photo-acoustic gas detection at 2 μm wavelengths. And there are a number of non-medical applications for which this technology might also be useful.”

The description of this project is available as an Adobe Acrobat PDF file:

Adobe Acrobat PDF file  SN PD 7 (194 KB)


University of Twente
Radboud University Nijmegen
Sensor Sense BV
Lionix BV
Utrecht Medical Center