New sensor technology to improve air quality in cities

What is meant by air quality in a Europe-wide research project? In concrete terms, the researchers want to develop new sensors within the framework of the Horizon 2020 research project CARES (new sensors that are attached to the roadside, guard rails, or traffic signs and detect passing vehicles within seconds.

"We want to monitor vehicle emissions in cities and environmental zones under real conditions without having to intervene in free-flowing traffic," explains Alexander Bergmann, head of the Institute for Electronic Sensor Systems at TU Graz. In the project, he and his team are primarily responsible for all aspects of particle measurement - an area in which the institute is one of the world's leading facilities.

Multiple options for traffic regulation

"The aim is to use the measurements to determine the emissions class of each individual vehicle," Bergmann explains. Cities could, for example, introduce an emissions-based congestion charge: the higher the car's exhaust emissions, the higher the fee to be paid. Entry permits in environmental zones could also be monitored automatically, with automatic barriers only opening if the pollutant emissions of the approaching car are within the normal range. Finally, the sensor system could be used to identify and remove from circulation vehicles that have been modified with manipulated particulate filters or chip tuning to increase engine output and thus pollutant emissions.

Tuning forks as particle gauges

Bergmann expects low-cost remote sensors for measuring emissions to be ready for series production by the end of the project in 2022 at the latest. However, he already points to the first promising tests at the institute, in which conventional tuning forks are being used. These are set in vibration by laser pulses. The particles located between the tines of the tuning fork are excited by the vibration and begin to "sing" in the truest sense of the word. Each individual particle emits acoustic signals that are picked up and reproduced by the tuning fork. The more particles there are, the louder the sound. The volume can then be used to determine how many particles are in the environment.

The technique is already being used successfully for gas measurements. "Our institute has now been able to show for the first time that this also works for particles and could be a possibility for a low-cost sensor," says Bergmann. The researchers at TU Graz hope that the measurement method will also prove its worth in the metropolises of Milan, Prague and Krakow, where the investigations are being carried out in real operation as part of the CARES project.

The research project CARES is funded by the Horizon 2020 research and innovation program of the European Union with 3.326.735,50 EUR and is anchored in the Field of Expertise "Information, Communication & Computing", one of five strategic focus areas of TU Graz.

Cooperation partner:

• Ivl Svenska Miljoeinstitutet (Lead Partner; SE)
• TU Graz (Institute for Electronic Sensor Systems; Institute for Combustion Engines and Thermodynamics AT)
• Airyx Gmbh (DE)
• AMAT (Agenzia Mobilita' Ambiente E Territorio; IT)
• AUTh (Aristotle University of Thessaloniki; GR)
• CTU (Czech Technical University in Prague; CZ)
• CULS (Czech University of Life Sciences Prague; CZ)
• EMPA (Swiss Federal Laboratories for Materials Testing and Research; CH)
• ICCT (International Council on Clean Transportation; DE)
• IIASA (International Institute for Applied Systems Analysis; AT)
• Innovhub - Stazioni Sperimentali Per L'industria (IT)
• Krakowski Alarm Smogowy (PL)
• TNO (Netherlands Organisation for Applied Scientific Research; NL)
• University of Heidelberg (DE)
• University Of Leeds (GB)
• University Of York (GB)

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