It is difficult to find out how much plastic and what kind is found in an environmental sample. Normally the water is filtered, and the residues are chemically analysed. But now there is a much simpler method. The spin-off usePAT from the Vienna University of Technology has developed a technology to directly localise and measure the tiny particles directly in the water sample. Ultrasonic waves serve to "trap and detect" the plastic particles at certain points. Then laser beams are used to determine the chemical composition of the particles.
"The filter and scan method used to comprise the conventional approach to confirming the presence of microplastics", says Christoph Gasser of the company usePAT. "However, this process is slow and cumbersome, and sometimes the results are falsified because of the filter being used. The solution developed by usePAT applies sound. An ultrasonic standing wave is generated in the sample container. The particles accumulate at the nodes. In this way the microplastics are concentrated at certain points. The analysis of the chemical composition is then carried out on the basis of Raman spectroscopy. Here the researchers exploit the fact that molecules change the wavelength of laser light in a characteristic manner. "Our ultrasound technologies enable us to substantially simplify many different measurement processes. Industrial demand is high", explains Georg Heinz from usePAT.
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