Screen-printed piezoelectric composites for vibrational energy harvesting in combination with structural composite laminates for powering a sensing node

This paper developed smart composite structures with screen-printed piezoelectric composite energy harvesters. P(VDF-TrFE) based composites with BaTiO₃ particles of different concentrations were deposited via screen printing and studied regarding surface morphology, crystalline structure, piezoelectric, dielectric and mechanical properties. It was identified that P(VDF-TrFE) with 5 wt% BaTiO₃ addition exhibited the best piezoelectric property. Even with a monotonic reduction in the β phase crystallisation as the BaTiO₃ concentration was increased, a 5 wt% inclusion of BaTiO₃ led to the rise of d₃₃ from −28.63 pC/N to −33.90 pC/N. This was attributed to the enhanced interfacial polarisation and the stress concentration induced by the addition of the ceramic particles. Subsequently, the printed piezoelectric composites were co-cured with glass fibre reinforced composites (GFRPs) and carbon fibre reinforced composites (CFRPs). The assembled harvesters were tested under both sinusoidal excitation and real industrial vibration. It was found that the smart composites with 5 wt% BaTiO₃ always manifested the best energy harvesting performance. For the optimised generator, maximum power of 2 μW and 1.5 μW could be obtained when using GFRPs and CFRPs as substrates under 1 g peak-peak sinusoidal excitation, respectively. The harvested energy could be used to power a commercial accelerometer with the help of a power management system. When exciting the GFRP-based energy harvester with an optimised printed piezoelectric generator at 7 g p-p acceleration, the power harvested was sufficient to maintain the operation of the accelerometer for 0.34 s.