Piezoelectric energy harvester for tyres: Bridging the research gap between materials and application

The increasing importance of tyre sensors to ensure safe driving and efficient tyre performance is driven by legislation targeting the reductions in fuel consumption and CO2 emissions. Tyre Pressure Monitoring Systems have become widely used to monitor the tyre pressure. This research project focuses on harnessing the potential of piezoelectric materials to power tyre sensors and enable their autonomous operation. Piezoelectric materials generate electrical energy when subjected to deformation, presenting a promising avenue for a continuous electricity production in tyres during dynamic driving conditions. Ceramics and polymers can serve as potential piezoelectric materials. On the one hand, ceramics offer high piezoelectric coefficients but are rigid, brittle, and heavy. On the other hand, piezoelectric polymers provide higher flexibility than ceramics but have lower piezoelectric coefficients.
The objective of this PhD thesis is to design a material capable of generating sufficient energy to power tyre sensors. To reach this goal, the first step was the development of an analytical setup to validate piezoelectric energy harvesters under simulated driving conditions. After that, the two key components of the harvesters, i.e. the piezoelectric material and the conductive material were investigated. The polymer PolyVinyliDene diFluoride (PVDF) and elastomeric composites filled with ferroelectric ceramic K0.5Na0.5NbO3 (KNN) were selected and studied as piezoelectric materials. Electrically conductive elastomers filled with conductive carbon blacks were selected as electrodes. The use of electrically conductive elastomers and good chemical adhesion with the piezoelectric components, enhanced the output power generated by both types of piezoelectric materials.
In conclusion, the present study presents advancements in material development and energy harvesting techniques for efficient and sustainable tyre performance monitoring. The research contributes to the ongoing improvement of the tyre safety and optimisation of the vehicle performance through innovative sensor technologies using alternative green energy.