We developed kinetic energy-harvestable and kinetic movement-detectable piezoelectric nanogenerators(PENGs)consisting of piezoelectric nanofiber(NF)mats and metal-electroplated microfiber(MF)electrodes using electrosp...We developed kinetic energy-harvestable and kinetic movement-detectable piezoelectric nanogenerators(PENGs)consisting of piezoelectric nanofiber(NF)mats and metal-electroplated microfiber(MF)electrodes using electrospinning and electroplating methods.Percolative non-woven structure and high flexibility of the NF mats and MF electrodes allowed us to achieve highly transparent and flexible piezocomposites.A viscoelastic solution,mixed with P(VDF-TrFE)and BaTiO_(3),was electrospun into piezoelectric NFs with a piezoelectric coefficient d33 of 21.2 pC/N.In addition,the combination of electrospinning and elec-troplating techniques enabled the fabrication of Ni-plated MF-based transparent conductive electrodes(TCEs),contributing to the high transparency of the resulting piezocomposite.The energy-harvesting efficiencies of the BaTiO_(3)-embedded NF-based PENGs with transmittances of 86%and 80%were 200 and 240 V/MPa,respectively,marking the highest values in their class.Moreover,the output voltage driven by the coupling effect of piezoelectricity and triboelectricity during finger tapping was 25.7 V.These highly efficient energy-harvesting performances,along with the transparent and flexible features of the PENGs,hold great promise for body-attachable energy-harvesting and sensing devices,as demonstrated in this study.展开更多
Flexible magnetoelectric （ME） materials have been studied for new applications such as memory, energy harvesters, and magnetic field sensors. Herein, with the widely studied and progressive advantages of ME phenomen...Flexible magnetoelectric （ME） materials have been studied for new applications such as memory, energy harvesters, and magnetic field sensors. Herein, with the widely studied and progressive advantages of ME phenomena in the multiferroic field, we demonstrate a new approach for utilizing flexible ME materials as gate dielectric layers in ME organic field-effect transistors （ME-OFET） that can be used for sensing a magnetic field and extracting the ME properties of the gate dielectric itself. The magnetoelectric nanohybrid gate dielectric layer comprises sandwiched stacks of magnetostrictive CoFe2O4 nanoparticles and a highly piezoelectric poly（vinylidene fluoride-co-trifluoroethylene） layer. While varying the magnetic field applied to the ME gate dielectric, the ME effect in the functional gate dielectric modulates the channel conductance of the ME-OFET owing to a change in the effective gate field. The clear separation of the ME responses in the gate dielectric layer of ME-OFET from those of the other parameters was demonstrated using the AC gate biasing method and enabled the extraction of the ME coefficient of ME materials. Additionally, the device shows high stability after cyclic bending of 10,000 cycles at a banding radius of 1.2 cm. The device has significant potential for not only the extraction of the intrinsic characterization of ME materials but also the sensing of a magnetic field in integrated flexible electronic systems.展开更多
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea Government(MIST)(RS-2023-00211303)Korea Institute for Advancement of Technology(KIAT)Grant funded by the Korea Government(MOTIE)(P0023521,HRD Program for Industrial Innovation).
文摘We developed kinetic energy-harvestable and kinetic movement-detectable piezoelectric nanogenerators(PENGs)consisting of piezoelectric nanofiber(NF)mats and metal-electroplated microfiber(MF)electrodes using electrospinning and electroplating methods.Percolative non-woven structure and high flexibility of the NF mats and MF electrodes allowed us to achieve highly transparent and flexible piezocomposites.A viscoelastic solution,mixed with P(VDF-TrFE)and BaTiO_(3),was electrospun into piezoelectric NFs with a piezoelectric coefficient d33 of 21.2 pC/N.In addition,the combination of electrospinning and elec-troplating techniques enabled the fabrication of Ni-plated MF-based transparent conductive electrodes(TCEs),contributing to the high transparency of the resulting piezocomposite.The energy-harvesting efficiencies of the BaTiO_(3)-embedded NF-based PENGs with transmittances of 86%and 80%were 200 and 240 V/MPa,respectively,marking the highest values in their class.Moreover,the output voltage driven by the coupling effect of piezoelectricity and triboelectricity during finger tapping was 25.7 V.These highly efficient energy-harvesting performances,along with the transparent and flexible features of the PENGs,hold great promise for body-attachable energy-harvesting and sensing devices,as demonstrated in this study.
文摘Flexible magnetoelectric （ME） materials have been studied for new applications such as memory, energy harvesters, and magnetic field sensors. Herein, with the widely studied and progressive advantages of ME phenomena in the multiferroic field, we demonstrate a new approach for utilizing flexible ME materials as gate dielectric layers in ME organic field-effect transistors （ME-OFET） that can be used for sensing a magnetic field and extracting the ME properties of the gate dielectric itself. The magnetoelectric nanohybrid gate dielectric layer comprises sandwiched stacks of magnetostrictive CoFe2O4 nanoparticles and a highly piezoelectric poly（vinylidene fluoride-co-trifluoroethylene） layer. While varying the magnetic field applied to the ME gate dielectric, the ME effect in the functional gate dielectric modulates the channel conductance of the ME-OFET owing to a change in the effective gate field. The clear separation of the ME responses in the gate dielectric layer of ME-OFET from those of the other parameters was demonstrated using the AC gate biasing method and enabled the extraction of the ME coefficient of ME materials. Additionally, the device shows high stability after cyclic bending of 10,000 cycles at a banding radius of 1.2 cm. The device has significant potential for not only the extraction of the intrinsic characterization of ME materials but also the sensing of a magnetic field in integrated flexible electronic systems.
