Beta-phase transformation of polyvinylidene fluoride with supersonically sprayed ZnSnO_(3) cuboids for flexible piezoelectric nanogenerators

Flexible self-powered electromechanical devices,such as piezoelectric nanogenerators(PENGs),which are used in wearable and implantable devices,are emerging as state-of-the-art clean energy sources.In this study,a scalable supersonic spraying technique was used to prepare flexible piezocomposite films of polyvinylidene fluoride(PVDF)and hydrothermally synthesized ZnSnO_(3)(ZSO)cubes for PENGs.Raman spectra confirmed that the transformation of the α-phase of PVDF to its β-phase was induced by the shear stress generated between the ZSO particles and PVDF polymer during supersonic spraying.The op-timized sample comprising 0.43 g of ZSO cubes and 1 g of PVDF produced a maximum piezopotential of 41.5 V and a short-circuit current,I_(sc),of 52.5 μA.A maximum power density of 50.6 μW cm-2 was ob-tained at a loading resistance of 0.4 MΩ,which matched the impedance of the PENG.Long-term tapping and bending cycles of N_(tap)=4200 and N_(bend)=600 yielded piezopotentials of 40.5 and 1.7 V,respectively.In addition,electrical poling for 2 h increased the piezopotential to 52 V owing to the alignment of the ferroelectric dipoles in the PVDF.

Wearable sensors and supercapacitors using electroplated-Ni/ZnO antibacterial fabric

Herein,nickel nanocones and zinc oxide nanosheets were electroplated onto a fabric to produce multifunctional(wearable,stretchable,washable,hydrophobic,and antibacterial)materials with sensing,heating,and supercapacitive properties.All these functionalities are integrated into a one-layered fabric that can be used as a portable intelligent electronic textile for potential application in healthcare monitoring,smart sportswear,and energy storage.Electroplated nickel enhances the electrical conductivity and thus increases the electron charge transfer for supercapacitor applications.The integration of ZnO with the Ni-plated fabric provides pseudocapacitance via redox reactions with the electrolyte.The resistance of the Ni/ZnO fabric changes in response to external stimuli such as temperature and strain.When voltage is applied,the fabric generates heat through Joule heating,demonstrating its potential application as winter sportswear.The superior mechanical durability of the fabric was confirmed through bending and stretching tests.The hydrophobic surface prevents viruses contained in liquid droplets from infiltrating the fabric.In addition,bacterial growth is inhibited because of the antibacterial properties of the Ni/ZnO fabric and because of Joule heating.The one-layered fabric integrated with such multiple functionalities is expected to be applicable in the development of next-generation portable and wearable electronic textiles in various industries.