A quick glance at your mobile phone or bike computer and you have up-to-date information about your tyre pressure at your fingertips. This is not a dream of the future, the EU project SYMPHONY - coordinated by JOANNEUM RESEARCH - is making it possible. This is important, for example, for the energy efficiency of e-bikes and safety when mountain biking.
What has long been standard for cars - automated tyre pressure monitoring - would also bring all kinds of benefits for cyclists. This is because tyre pressure has a direct effect on rolling resistance, riding comfort, grip, puncture protection and therefore also safety. For e-bikes (3-8 bar), for example, the rolling resistance has an influence on the battery life. In triathlons (8 bar), rolling resistance is a decisive factor and in mountain biking (1.5-2 bar), grip is strongly influenced by tyre pressure. In all cases, regular pressure checks are advisable. But where should the power for data transmission come from inside the inner tube? The EU project SYMPHONY is looking into this: it aims to generate energy in a cost-efficient and environmentally friendly way, without a cable connection or battery.
Energy harvesting: kinetic energy is converted into electricity
"The deformation of the hose during the journey is converted into energy, which is used to transmit sensor data. This means that kinetic energy is converted into electrical energy," says project coordinator Jonas Groten from the MATERIALS Institute. "This requires a material with electromechanical properties as a converter." Until now, lead compounds, which are toxic, have often been used for this purpose. And now the MATERIALS Institute is coming into play: Researchers here have been working with the piezoelectric polymer PVDF for more than 10 years. The advantages: PVDF is non-toxic and is both cost-effective and can be printed over large areas. Under certain conditions, this polymer forms a structure in which the smallest molecular dipoles add up over a large area. This is known as remanent polarisation. If this polymer is now deformed, this polarisation changes, as does the number of electrical charges in the electrodes applied to the polymer. If these electrodes are connected, electricity is generated during mechanical deformation. Together with the Viennese bicycle tube manufacturer Tubolito and the semiconductor producer Infineon, the system was subjected to a mechanical stress test equivalent to a 5000 km ride.
Wide range of applications
However, this technology not only makes bicycle inner tubes "intelligent", it can be used wherever sensors generate data and a self-sufficient energy system is advantageous, for example because cabling is out of the question or a battery or photovoltaic supply is not expedient: In the walls of houses, in the bodywork of vehicles, in the floor, in toys or in agriculture. Two further application examples for the energy-converting polymer are being investigated as part of SYMPHONY: Condition monitoring in a wind turbine and energy-efficient room heating and cooling in a smart home.
The EU-Project SYMPHONY (Smart Hybrid Multimodal Printed Harvesting of Energy) has been running since 2020 and will be completed in April.
Projectcoordinator: Dr Jonas Groten, +43 316 876-3109
Project partners: JOANNEUM RESEARCH MATERIALS, Würth Elektronik eiSos GmbH & Co. KG, Semperit Technische Produkte GmbH, Fraunhofer Institute for Silicate Research ISC, Tubolito GmbH, Polymer Competence Center Leoben GmbH, Research Institute of Sweden RI.SE, Messfeld GmbH, Infineon Technologies Austria GmbH, Linköpings Universitet, Eologix Sensor Technology GmbH, Arkema France SA, InnovationLab GmbH
