RESUMO
Due to its invaluable potential in discrete mechanical energy collection, TENG (triboelectric nanogenerator) is considered to satisfy the power requirements of intelligent electronic devices and drive the development of the Internet of Things (IoT). Nowadays, the promotion of TENGs has been hindered due to the limitation of their output performance and service life. Herein, a brand new triboelectric nanogenerator based on a multi-material stacking structure is proposed. By stacking various triboelectric materials in a specific order, a special charge balance state could be achieved inside the system such that the conductive layer generates more induced charges, and the output performance is significantly enhanced. Besides, due to the usage of the electropositive elastomer PU (polyurethane sponge), the design also effectively alleviates abrasion on the contact surface and adjusts its own output according to different compression environments. The experimental results show that the stacked PTFE/FKM/PU TENG (PFP-TENG) presents a more than 50% increase in transferred charge and almost 5 times the current output compared with the general contact-separation type TENG. When connected to the application circuit, the maximum output power reached 10.2 W m-2 and 145.2 W m-3, and more than 1400 LEDs could be easily lit. Finally, the PFP-TENG was also used to collect mechanical energy from simple motion and realize considerable power generation. This study not only provides new ideas for the design of TENGs by reasoning the theoretical model but also presents improved output performance, thus exemplifying the strong potential of this design in developing a power-generation device that can collect discrete mechanical energy.
RESUMO
To combine the advantages of elastic and nonelastic triboelectric materials, this work proposes a new type of triboelectric nanogenerator (TENG) based on stacking -the stacked FKM/PU TENG. By stacking the elastomer polyurethane (PU) and the nonelastomer fluororubber (FKM), the FKM/PU TENG combines the inherent triboelectric characteristics of both materials and the unique elasticity of PU to achieve an output performance that is much higher than that of the FKM-TENG or the PU-TENG. The maximum instantaneous open-circuit voltage and short-circuit current of the FKM/PU TENG reach 661 V and 71.2 µA, respectively. Under the limiting conditions of 3 Hz and maximum compression, this device can attain a maximum power density of 49.63 W/m3 and light more than 500 LEDs. Therefore, stacking materials with different properties gives the FKM/PU TENG high output performance and great application potential, which can contribute to future development of discrete mechanical energy harvesting.
RESUMO
Chronic kidney disease has become a worldwide public health problem, and it negatively affects oral health. However, the data of the hemodialysis (HD) patients in Chinese population is unknown. This study was aimed to evaluate the dental health status and oral hygiene behavior of the HD patients in China. Patients undergoing HD therapy at two hospitals were asked to finish a questionnaire and receive dental examination (DMF-T). A total of 306 patients, aged 24-88 (58.09 ± 14.06), took part in this study. Although majority of the patients (77.78%) brushed their teeth at least twice a day, few (less than 5%) had ever used dental floss or mouthwash. More than half of the patients have not visited a dentist since the commencement of HD therapy. The dental examination showed that DMF-T was 9.63 ± 7.54, and the number of filled teeth (F-T) was only 0.70 ± 1.48. Moreover, the average caries restoration ratio and replacement index were 17.57% and 32.59%, respectively. HD therapy seems to prevent patients from visiting a dentist, and there is a great need for dental treatment for Chinese HD patients.