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How a polymer converts energy and makes bicycle tubes 'smart'

How a polymer converts energy and makes bicycle tubes 'smart'

Glance at your cell phone or bike computer and you'll see up-to-date information about your tire pressure. This is not something of the future, but rather the EU project SYMPHONY – coordinated by JOANNEUM RESEARCH – makes it possible. This is important, for example, for energy efficiency in e-bikes and safety when riding mountain bikes.

What has long been a standard in cars — automatic tire pressure monitoring — would also bring all kinds of benefits to cyclists. Tire pressure directly affects rolling resistance, driving comfort, grip, but also puncture protection, and thus safety. For e-bikes (3-8 bar), for example, rolling resistance has an impact on battery life. In triathlon racing (8 bar), rolling resistance is a decisive factor, and in mountain biking (1.5-2 bar) grip is strongly affected by air pressure. In all cases, regular pressure checking makes sense. But where should the electricity needed to transmit data inside a bicycle tube come from? This is what the EU project SYMPHONY is concerned with: it aims to generate energy in a cost-effective and environmentally friendly way, without connecting a cable or battery.

Energy harvesting: Kinetic energy is converted into electricity

“The deformation of the hose during driving is transformed into energy through which sensor data is transmitted. That is to say: kinetic energy is transformed into electrical energy,” says project coordinator Jonas Groten from the Materials Institute. “For this you need a material with electromechanical properties as a transformer.” Until now, toxic lead compounds are often used for this purpose. Now comes the Materials Institute's turn: Researchers here have been working on the piezoelectric polymer PVDF for more than 10 years. Advantages: PVDF is non-toxic, cost effective and can be printed over large areas. Under certain conditions, this polymer forms a structure in which the smallest molecular dipoles are aggregated over a large area. This is then referred to as permanent polarization. If this polymer now deforms, this polarization changes, and therefore the number of electric charges in the electrodes applied to the polymer also changes. If you connect these electrodes, electricity is generated when they are mechanically deformed. With Vienna bicycle tube manufacturer Tubolito and semiconductor manufacturer Infineon, the system was subjected to a mechanical stress test equivalent to a distance of 5,000 kilometers.

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Diverse application possibilities

Not only does this technology make bike tubes “smart”, it can be used anywhere sensors are generating data. A self-sufficient power system is an advantage, for example, because wiring them is out of the question or powering them with a battery or photovoltaics is inefficient: In the walls of houses, in the bodies of vehicles, in the ground, in toys or in agriculture. As part of SYMPHONY, two additional application examples of energy-converting polymer are being studied: condition monitoring in wind turbines and energy-efficient space heating. Or smart home cooling.

The EU project SYMPHONY (Smart Multimodal Printed and Hybrid Energy Harvesting) has been running since 2020 and will be completed in April.

project coordinator: doctor. Jonas Groten, +43 316 876-3109

Project partners: Research materials JOANNEUM, Würth Elektronik eiSos GmbH & Co. KG, Semperit Technischeprodukte GmbH, Fraunhofer Institute for Silicate Research ISC, Tubolito GmbH, Polymer Competence Center Leoben GmbH, Swedish Research Institute RI.SE, Messfeld GmbH, Infineon Technologies Austria GmbH, Linköpings Universitet, Eologix Sensor Technology GmbH, Arkema France SA, InnovationLab GmbH

JOANNEUM RESEARCH is a company providing innovation and technology in applied research. As a research company for countries and regions, we use our research skills to shape the development of our modern society and economy in a sustainable, people-centred way. As an interdisciplinary team in flexible and innovation-friendly structures, we live up to the highest social and scientific standards.



Dr. Jonas Groten 
MATERIALS - Institut für Sensorik, Photonik und Fertigungstechnologien 
Franz-Pichler-Straße 30, 8160 Weiz 
Tel.:  +43 316 876-3109, E-Mail: [email protected]