Recently, the nanogenerators which can convert the mechanical energy into electricity by using piezoelectric one-dimensional nanomaterials have exhibited great potential in microscale power supply and sensor systems. In this paper, we provided a comprehensive review of the research progress in the last eight years concerning the piezoelectric nanogenerators with different structures. The fundamental piezoelectric theory and typical piezoelectric materials are firstly reviewed. After that, the working mechanism, modeling, and structure design of piezoelectric nanogenerators were discussed. Then the recent progress of nanogenerators was reviewed in the structure point of views. Finally, we also discussed the potential application and future development of the piezoelectric nanogenerators.
The rapid development of microscaled piezoelectric energy harvesters has provided a simple and highly efficient way for building self-powered sensor systems through harvesting the mechanical energy from the ambient environment. In this work, a self-powered microfluidic sensor that can harvest the mechanical energy of the fluid and simultaneously monitor their characteristics was fabricated by integrating the flexible piezoelectric poly(vinylidene fluoride) (PVDF) nanofibers with the well-designed microfluidic chips. Those devices could generate open-circuit high output voltage up to 1.8 V when a droplet of water is flowing past the suspended PVDF nanofibers and result in their periodical deformations. The impulsive output voltage signal allowed them to be utilized for droplets or bubbles counting in the microfluidic systems. Furthermore, the devices also exhibited self-powered sensing behavior due to the decreased voltage amplitude with increasing input pressure and liquid viscosity. The drop of output voltage could be attributed to the variation of flow condition and velocity of the droplets, leading to the reduced deformation of the piezoelectric PVDF layer and the decrease of the generated piezoelectric potential.
The development of self-powered vibration sensors using polymeric piezoelectric nanomaterials has attracted great attention owing to their outstanding flexibility and energy harvesting behaviours. In this study, ultra-long poly (vinylidene fluoride) (PVDF) nanofibres with optimised β-phase content were synthesised through electrospinning method with different DC voltages. The increase in the β-phase content of the PVDF nanofibres greatly enhanced their piezoelectric response with nearly tripled output voltage and current under the same strain condition. Moreover, the output voltage exhibited linear correlations with both the amplitude and frequency of the strain. Under a fixed frequency of 1.54 Hz, the output voltage exhibited a linear correlation to the strain amplitude with strain sensitivity up to 0.92 V rad −1 and 0.61 V mm −1 . The frequency-dependent strain sensing behaviour also confirmed the necessity for frequency calibration to the measured results of vibration. Accordingly, the sensor can be used for selfpowered monitoring of the vibration state of a metal foil and measuring the intrinsic resonance frequency of the objects without any powering source.
We present a novel hybrid electrodes based on reduced graphene oxide/nickel/zinc oxide heterostructures. The sensor was fabricated by template-free hydrothermal growth of ZnO nanorod arrays on conductive glass substrates (FTO) followed by conformal electrodeposition of nickel nanoparticles with an average size of 18 nm. Then, in-situ reduction and electrophoretic deposition of graphene oxide (GO) nanosheets on the structured ZnO/Ni electrode was performed. The prepared three-dimensional nanostructure exhibited fast electrocatalytic response (<3s) towards glucose oxidation due to the large surface area and high electro-activity. The prepared biosensor possessed a wide linear range over 0.5 μM to 1.11 mM, a low detection limit of 0.15 μM at signal/noise ratio (S/ N) of 3, and a sensitivity of 2030 µAcm-2 mM-1. Therefore, the performance of the sensor regarding the detection limit and sensitivity is better than many other electrodes utilized for non-enzymatic glucose detection. No interference from different electroactive substances such as uric acid and ascorbic acid is also noticed. The potential application of the 3D hybrid biosensors for detection of glucose in real human serum samples is shown. This novel structured electrode holds great promise for the development of biosensors and other electrochemical devices.
A humidity sensor based on NaNbO 3 nanofiber networks was fabricated through the electrospinning process. The as-synthesized NaNbO 3 nanofibers with monoclinic perovskite structure are uniformly distributed and integrated by interdigital Pt/Ti electrodes on alumina substrates. The sensor exhibits fast and ultra-sensitive resistance type response to the variation of environmental humidity at room temperature. The sensor resistance is in logarithmic dependence on the relative humidity. The highest sensitivity is up to 10 5 for the humidity change from 20 to 80% RH. Moreover, the response time for the humidification process is less than 3 s. The response time for the dehumidification process is slower due to the slower desorption of water molecules. In addition, the sensor exhibits outstanding selectivity against hydrogen, ethanol, and acetone steam. Among them, the sensitivity to ethanol steam is 5 orders of magnitude smaller than that to humidity, while no sensing response is found for hydrogen and acetone. According to the fully recovered performance and non-sensing behavior to hydrogen, the sensing behavior of the nanofibers could be attributed to the electrical-field-driven transfer of proton between H 3 O + induced by the physisorption of water molecules.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.