Piezoelectric polymer-based roadway energy harvesting via displacement amplification module

Recent research efforts show that piezoelectric polymers such as PVDF are competitive alternatives to the conventional piezoelectric ceramics. While possessing extraordinary toughness and fatigue resistance, however, piezoelectric polymers suffer from limited applications due to a large amount of deformation required for high power output. Here, we design and demonstrate a PVDF-based, high-power piezoelectric module installed on a local highway, for the first time. The module contains a bridge-type displacement amplification capability, demonstrating the 2.5 mm vertical displacement converted into 13 mm horizontal deformation, suitable for the uninterrupted driving experience. We provide the design guidelines and optimization strategies for the module, in terms of the piezoelectric power output. With 80 bimorph-shaped energy harvesters, the module achieves up to 16.5 W/m² energy density when the test vehicle passes by at 80 km/h. The matching impedance decreases with vehicle speed, suggesting that different matching impedance should be used for highway and local roadways. The output power exhibits a linear relation to the vehicle speed and weight, implying the module's potential application as a self-powered speed sensor. The study demonstrates that PVDF-based energy harvesters provide a competitive power output at small vertical displacements with relevant module design, making the tough piezoelectric materials suitable for efficient and durable roadway energy harvesting.