Over many years, researchers at TU Wien have developed an unusual new measurement technique: nanomembranes and infrared light are used to detect extremely small quantities of different substances. It has now been demonstrated that the technology is ready for practical use and outperforms existing methods by orders of magnitude in many respects. Environmental pollutants can be detected in the nano- or picogram range – results that previously required days or even weeks can now be obtained within minutes.
This measurement technique has been developed and refined at TU Wien over the past years in collaboration with the spin-off company Invisible-Light Labs, founded by Prof. Silvan Schmid together with Dr. Josiane P. Lafleur, Dr. Niklas Luhmann, and Dr. Hajrudin Bešić. The resulting product, EMILIE™, is now commercially available, and the first scientific publications have appeared. In two research articles, the team has demonstrated how well the new method performs: in Science Advances, it was applied to aerosols in the air, and in ACS Nano to nanoparticles in water – even enabling the detection of minute traces released from a nylon teabag into tea. “We have now reached the decisive milestone: we were able to show that our method delivers excellent results in real-world applications and clearly outperforms other techniques.”
“In principle, it is already possible today to detect almost any chemical substance in trace amounts,” says Silvan Schmid, head of the research team. “For example, a sample can be illuminated with many different wavelengths in the infrared range. Different molecules respond to different wavelengths – and from that, we can determine which molecules are present in the sample.”
However, this approach has its limitations: a sufficient amount of the target substance is required to generate a measurable signal. Other, irrelevant components of the sample can obscure the signal of interest and render it invisible – much like the noise of a jackhammer drowning out the song of a bird.
“In recent years, we have developed a detection method that makes it possible to reliably measure extremely small quantities of material,” says Silvan Schmid. The method analyzes particles that accumulate on a tiny membrane. The membrane, together with the particles, is illuminated with infrared light. Certain wavelengths are strongly absorbed by the particles, causing them – and thus the membrane – to heat up slightly. This leads to a tiny change in the membrane’s vibrational behavior – similar to how a drum sounds slightly different depending on its temperature. These changes can be measured with great precision, allowing even very small particle quantities to be chemically identified.
In the past, detecting ultrafine particulate matter in air required special filters through which air had to be pumped for days or even weeks until a sufficient amount of particles had accumulated. With the new membrane-based approach, far fewer particles are needed – results can be obtained after just 15 to 45 minutes. This 100-fold reduction in sampling time enables cost-effective field studies of the chemical composition of atmospheric aerosols – from densely populated urban areas to remote polar regions.
Prof. Julia Schmale from the Extreme Environments Research Laboratory (EERL) at EPFL in Switzerland used the new method to investigate aerosols from Arctic and Antarctic regions in order to better understand their impact on the climate. The sensors are both highly sensitive and sufficiently portable to be deployed on tethered balloons in polar regions, allowing researchers to study the vertical distribution and chemical composition of airborne particles.
“Thanks to the high sensitivity of our method, Julia Schmale’s team can analyze the chemical composition of particles with high temporal resolution. It is now possible, using tethered balloons, to observe how the chemical composition of aerosol particles changes over short timescales and how it varies between ground level and higher altitudes – something that was practically impossible with previous methods,” explains Josiane P. Lafleur, CEO of Invisible-Light Labs.
The technology also works extremely well for liquids: the research group led by Silvan Schmid at TU Wien analyzed just 100 nanoliters of tea water – roughly one thousandth of a drop. Even in this tiny amount, they were able not only to detect components of the tea itself, but also traces of nylon released from the teabag.
“We have demonstrated that our method represents a major step forward in environmental analytics,” says Silvan Schmid. “Together with Invisible-Light Labs, we now aim to further commercialize this technology and hopefully contribute to more effective environmental protection.”
Science Advances
Experimental study
Not applicable
Quantifying submicrometer atmospheric aerosol chemical composition using nanoelectromechanical Fourier transform infrared spectroscopy
22-Apr-2026