RESUMO
Figure of merit the product of piezoelectric charge constant and the piezoelectric voltage constant-d33 × g33 in piezoelectric energy harvesting systems are critical measures in energy harvester applications. It is difficult to achieve high figure of merit because of the interdependence of d33 and the relative dielectric constant, εr. Until now, the prohibitive amount of effort required to solve this problem has led to it being considered an unsolvable issue. Lead zirconate titanate ceramic, Pb(Zr,Ti)O3, has been reported to exhibit high values of d33 and εr. However, to be employed as piezoelectric energy harvester, a candidate material is required to exhibit both high piezoelectric charge coefficient and high piezoelectric electric voltage coefficient simultaneously. To enhance the figure of merit of Pb(Zr,Ti)O3-based materials, dopants have also been considered. Pb(Zn,Ni,Nb)O3- added Pb(Zr,Ti)O3, Pb(Zr,Ti)O3-Pb(Zn,Ni,Nb)O3 ceramic has been reported to exhibit a high d33 value of 561 pC/N. It's dielectric constant has also been reported to be low at 1898. In this study, Pb(Zr,Ti)O3-Pb(Zn,Ni,Nb)O3-Pb(In,Nb)O3 was investigated in the context of enhancing the figure of merit of Pb(Zr,Ti)O3-based materials. During the proposed process, we increased the corresponding figure of merit by adding Pb(In,Nb)O3 material. Besides exhibiting a low dielectric constant, the Pb(In,Nb)O3 material was also observed to exhibit high d33 × g33 as the proposed doping increased the value of d33 greatly, while maintaining the dielectric constant (Yan, J., et al., 2019. Large engancement of trans coefficient in PZT-PZN energy harvesting system through introducing low εrPIN relaxor. Journal of the European Ceramic Society, 39, pp.2666-2672). Further, we conducted an optimization experiment by controlling the doping concentration and the sintering temperature.
RESUMO
As a piezoelectric material, (Bi,Sc)O3-(Pb,Ti)O3 ceramics have been tested and analyzed for sensors and energy harvester applications owing to their relatively high Curie temperature and high piezoelectric coefficient. In this work, we prepared optimized (Bi,Sc)O3-(Pb,Ti)O3 piezoelectric materials through the conventional ceramic process. To increase the output energy, a multilayered structure was proposed and designed, and to obtain the maximum output energy, impedance matching techniques were considered and tested. By varying and measuring the energy harvesting system, we confirmed that the output energies were optimized by varying the load resistance. As the load resistance increased, the output voltage became saturated. Then, we calculated the optimized output power using the electric energy formula. Consequently, we identified the highest output energy of 5.93 µW/cm2 at 3 MΩ for the quadruple-layer harvester and load resistor using the impedance matching system. We characterized and improved the electrical properties of the piezoelectric energy harvesters by introducing impedance matching and performing the modeling of the energy harvesting component. Modeling was conducted for the piezoelectric generator component by introducing the mechanical force dependent voltage sources and load resistors and piezoelectric capacitor connected in parallel. Moreover, the generated output voltages were simulated by introducing an impedance matching technique. This work is designed to explain the modeling of piezoelectric energy harvesters. In this model, the relationship between applied mechanical force and output energy was discussed by employing experimental results and simulation.
RESUMO
BACKGROUND: Sand blasted titanium (Ti) is commonly used in designing endosseous dental implants due to its biocompatibility and ability to form bonds with bone tissues. However, titanium implants do not induce strong interactions with teeth bones. To increase strong interactions between Ti disk implants and teeth bones, the l-glutamic acid grafted hydroxyapatite nanorods (nHA) were immobilized on albumin modified Ti disk implants (Ti-Alb). METHODS: For modification of Ti disk implants by nHA, the l-glutamic acid grafted nHA was synthesized and then immobilized on albumin modified Ti disk implants. Fourier transformed infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscope; energy dispersive spectroscopy and confocal laser scanning microscopy were used to confirm the modification of Ti disk implants. The bioactivity of nHA-modified Ti disk implants was evaluated by seeding MC3T3-E1 cells on Ti-nHA implants. RESULTS: Characterization techniques have confirmed the successful modification of Ti disk implants by l-glutamic acid grafted nHA. The nHA-modified Ti disk implants have shown enhanced adhesion, proliferation and cytotoxicity of MC3T3-E1 cells in comparison to pristine Ti implants. CONCLUSIONS: The modification of Ti implants by l-glutamic acid grafted nHA has produced highly osteogenic Ti disk plants in comparison to pristine Ti disk implants due to the formation of bioactive surfaces by hydroxyapatite nano rods on Ti disk implants. Ti-nHA disk implants showed enhanced adhesion, proliferation, and MC3T3-E1 cells viability in comparison to pristine Ti disk implants. Thus nHA might be to be useful to enhance the osseointegration of Ti implants with teeth bones.
