Design and performance of flexible polymeric piezoelectric energy harvesters for battery-less tyre sensors

Abstract

A piezoelectric energy harvester for battery-less tyre sensors has been developed. It consists of two elements: 1) a piezoelectric material - PolyVinyliDene diFluoride (PVDF) film and 2) an electrode - a conductive elastomer filled with carbon black and Single-Wall Carbon NanoTubes (SWCNT). It was designed as a flexible patch in a sandwich-like configuration, which can be mounted onto the inner liner of a tyre. The patch was fabricated by inserting a PVDF film in between two conductive elastomer sheets. The development started with improving the conductivity of the elastomer by adding 6 wt% of SWCNT masterbatch. The adhesion between the interfaces was improved through surface modification of the PVDF film by introducing oxygen functional groups via a plasma treatment and further modification with a thiocyanate silane. The successful surface modification of the PVDF film was affirmed by x-ray photoelectron spectroscopy. T-peel and fatigue tests showed durable and stable adhesion between PVDF and conductive elastomer, confirming that the silane can effectively bridge the two components. A glueing method is proposed to adhere the patch to the tyre inner liner compound. The harvester is estimated to sufficiently power a reference tyre sensor, producing 28 μW/cm2.

Simulated and measured piezoelectric energy harvesting of dynamic load in tires

“…Another piezoelectric-based material is poly (vinylidene fluoride) (PVDF) that is flexible, enables large deformation making it also good candidate for tire applications. even it has lower piezoelectric constant than ceramic PZT [ [19] , [20] , [21] ]. Lee and Choi [ 22 ] used PVDF film obtaining 380 μJ per revolution at 60 km/h and 500 kg load, converting and using approximately 9.7% of the available energy.…”