[en] A high-performance flexible piezoelectric hybrid nanogenerator (HNG) based on lead-free perovskite zinc stannate (ZnSnO_3) nanocubes and polydimethylsiloxane (PDMS) composite with multiwall carbon nanotubes (MWCNTs) as supplement filling material is demonstrated. Even without any electrical poling treatment, the HNG possesses an open-circuit voltage of 40 V and a short-circuit current of 0.4 μA, respectively, under repeated human finger impact. It has been demonstrated that the output volume power density of 10.8 μW cm"−"3 from a HNG can drive several colour light emitting diodes (LEDs) and a charge capacitor that powers up a calculator, indicating an effective means of energy harvesting power source with high energy conversion efficiency (∼1.17%) for portable electronic devices. (paper)

[en] The electroactive β -phase is most desirable due to its highest piezo-, pyro- and ferroelectric properties in poly(vinylidene fluoride) (PVDF). Induction of the β -phase is successfully accomplished in titanium dioxide (TiO₂) nanoparticles (NPs) doped spin-coated PVDF nanocomposite (PNC) films. The optimized yields of β -phase and homogeneous ultra-smooth free-standing PNC film is utilized in a mechanical-energy harvesting application by fabricating a nanogenerator (NG) where the typical electrical poling step is not undertaken. Under a repeated human finger touch and release process, it delivers an open-circuit voltage of 5 V. Moreover, the physical sensing capabilities of the NG are examined through harvesting mechanical energy from mouse clicking of a laptop and wrist pulse detection, which indicates that it can also be used as a nanosensor. The blue photoluminescence centred at 444 nm, which was also observed in PNC films, makes us anticipate a new type of photonic application where the design feasibility of hybrid sensors, i.e. electromechanical and photonic combination, is also possible. (paper)

[en] Highlights: • A pyroelectric generator as a self-powered temperature sensor has been demonstrated. • A self-sustaining pyroelectric generator has been realized. • It harvests heat dissipation from human body surface. • It has the potential to use as self-powered breathing sensor. • The possibility of non-invasive human healthcare monitoring has been shown. Conversion of temperature fluctuations to useable electrical energy is rendered by the pyroelectric effect. Waste of heat in our day to day environment and in industrial sector constitutes an abundant source of energy. Herein, we report a pyroelectric generator (PyG) that produces pyroelectric output up to 1.5 V and 1.5 µA. Its power density is 0.034 µW/cm² upon exposure to heat-cool condition for a temperature variation from 310 K to 340 K. Due to the fast response time (121 ms) of the PyG, it is expected to be use as a self-powered temperature sensor. The generated electricity could also be stored in a capacitor up to 0.8 V in three heating–cooling cycles. It has been also demonstrated that PyG is possible to drive by water vapour where energy-consuming alternating devices is not necessary. The temperature oscillation achieved by spontaneous water condensation and evaporation from the surface of the PyG that produces open-circuit voltage of 1.6 V for a temperature variation from 303 K to 333 K. Thus the PyG driven by water vapour supports an efficient retrieval of energy from hot water vapour, which is wasted mostly. The linear increment of voltage as a function of temperature indicates PyG is also suitable to use a temperature sensor that may also work in self-powered mode. In addition, the PyG can also harvest the waste body heat, i.e., heat dissipation from human body surface and from the process of respiration. That promises an effective self-powered temperature sensor that might be useful in healthcare monitoring, safety and security sectors.

[en] Highlights: • A flexible multifunctional piezoelectric nanogenerator is demonstrated. • It possesses resonance frequency at 86 ± 3 Hz and an acoustic sensitivity of ∼3 V Pa⁻¹. • It is capable of acting as a self-powered microphone for sound recording. • A very high wind energy conversion efficiency of ∼58% is achieved. • It is capable of detecting human exhalation. -- Abstract: Piezoelectric nanogenerators are forthcoming alternative choices for scavenging different types of wasted mechanical energies. An inorganic-organic hybrid piezoelectric nanogenerator (HPNG) has been realized by incorporating zinc sulphide nanorods (ZnS-NRs) into electrospun poly(vinylidene fluoride) (PVDF) nanofibers for self-powered multifunctional sensing. As an acoustic energy harvester, the HPNG possesses a resonance frequency of 86 ± 3 Hz and an acoustic sensitivity of ∼3 V Pa⁻¹. It can distinguish sound waves from low to mid frequency region that makes it suitable for noise detection. In addition, HPNG demonstrates the very high wind energy conversion efficiency of ∼58% that make it capable of detecting human exhalation. Apart from its noise detection and power generation capabilities, HPNG is possible to use as a self-powered microphone. This electromechanical coupling, integrated with their flexibility, makes it usable as a flexible electro-acoustic sensor for security purpose as well. These results establish the potential of hybrid piezoelectric structure, with their multi functionalities for several promising applications such as noise detection, wind energy harvesting, security monitoring and most promisingly to develop the self-powered system.

[en] The development of a new kind of self-powered vibration sensor (SPVS) with cantilever structure made with polymeric piezoelectric material for low frequency vibrations detection is demonstrated. Methylammonium lead bromide (MAPB) particles incorporated poly(vinylidene fluoride) (PVDF) composite film exhibiting significant yield of piezoelectric β-phase and outstanding flexibility that resulting superior mechanical energy harvesting behaviour. The composite films also possess relatively increased dielectric constant than PVDF film. The resonance frequency and amplitude of damping vibrations have been determined utilizing the output voltage of the SPVS without any power source. Thus, SPVS might be useful in detecting low frequency vibrations in self-powered mode. (paper)

[en] Highlights: • CH₃NH₃PbBr₃ doped electrospun PVDF nanofiber based piezoelectric NG is fabricated. • The NG exhibits a high acoustic sensitivity and efficiency. • Green light emission capability of the nanofiber is useful in optoelectronic devices. • Remarkable capability to detect several speeches is demonstrated. Methylammonium lead bromide (CH₃NH₃PbBr₃) (MAPbBr) has been synthesized and then introduced in the poly(vinylidene fluoride) (PVDF) nanofiber made by the process of electrospinning. The β-phase composition, degree of crystallinity as well as mechanical, optical and energy harvesting properties of this composition has been investigated. Increased electroactive phase composition (91%) and dramatic improvement in tensile strength of the PVDF nanofiber mats is found by the addition of MAPbBr. This increase in electroactive phase composition can play a significant role in the enhancement of output power which is a premiere observation. The acoustic nanogenerator (ANG) made from MAPbBr doped PVDF nanofibers (NFs) can also be utilized in energy scavenging from acoustic vibration with a higher degree of acoustic sensitivity (~ 13.8 V Pa⁻¹) and efficiency (58.5%). This suggests that ANG could be a potential tool for power generation in portable electronics. This fact may open up the prospect of using the MAPbBr doped PVDF electrospun nanofibers, with their multifunctional properties such as vibration sensitivity, piezoelectric energy harvesting, green light emission capability (quantum yield ~ 32.6%), for various promising applications in portable electronics, noise detection and security monitoring.