Fabrication of flexible energy harvesting device based on K0.5Na0.5NbO3 nanopowders

• K0.5Na0.5NbO3 (KNN) nanopowders were fabricated by using sol–gel method.
• An energy harvesting device based on KNN nanopowders were fabricated.
• The mechanism of the device relies on the piezoelectric effect of KNN materials.
• The power delivered to the outer load under an external force was estimated.

K0.5Na0.5NbO3 (KNN) powder was synthesized by a novel sol–gel method and used to fabricate an energy harvesting device. The precursor gel and KNN powder were studied by thermogravimetric analysis (TG), differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The elemental composition of the KNN powder was characterized by energy dispersive X-ray analysis (EDAX). Well crystallized single phase perovskite KNN powder with an average particle size on the order of 450 nm was obtained from the gel after calcining at 750 °C for 2 h. A flexible and implantable energy harvesting device fabricated using the KNN nanopowder exhibited an output power of up to 0.13 μW with a load resistance of 100 MΩ. The Young’s modulus of the device was determined to be 10.4 GPa by atomic force microscopy (AFM).