•Wearable PyNG for human breathing energy harvesting.•Self-powered human breathing monitoring and ambient temperature detection.•Demonstrating excellent output performance and unencumbered wearable mode.Wasted heat is one of the most abundant and widely available energy sources in our living environment and industrial activities. Pyroelectric nanogenerators (PyNGs) is emerging as a powerful tool to scavenge wasted heat. Here we designed and fabricated a wearable PyNG using PVDF thin film integrated in a N95 respirator for scavenging energy of human respiration. Due to the temperature fluctuation induced by human breathing at 5 °C ambient temperature, the PyNG can generate output signals with an open-circuit voltage of 42 V and a short-circuit current of 2.5 μA, respectively. The maximal power reached up to 8.31 μW with an external load of 50 MΩ, which can be utilized to directly drive electronics, such as a liquid crystal display and light emitting diodes. This PyNG has also been demonstrated as self-powered human breathing and temperature sensors. The excellent performances and unencumbered wearable mode of the PyNG demonstrate that the device can be developed as a promising wearable energy harvester and self-powered multifunctional sensors for practical applications.Download high-res image (119KB)Download full-size image

A high output flexible piezoelectric generator based on a highly oriented BaTiO3 film self-assembled using an interfacial strategy is reported. We have successfully controlled the morphology and orientation of BaTiO3 particles and obtained a BaTiO3 film using a facile interfacial self-assembled method. The BaTiO3 film is transferred onto an ITO coated PET substrate and packaged with PDMS (polydimethylsiloxane) to form a flexible piezoelectric energy harvesting device. The interfacial assembling strategy can effectively increase the volume fraction of active piezoelectric materials in composite films. The BaTiO3 film-based piezoelectric generator was demonstrated to harvest wind energy by employing a windmill and the output power was large enough to light a LCD.

•Hybrid piezoelectric fibers, metal wires and cotton threads were woven into a fabric nanogenerator.•The electrodes are naturally integrated in the fabric so that the device looks similar to the conventional fabrics.•By attaching the fabric nanogenerator on an elbow pad, the output power of the nanogenerator is large enough to power a LCD.Wearable nanogenerators are vital important for wearable devices and portable electronic devices. Here we report a flexible hybrid piezoelectric fiber based two-dimensional fabric nanogenerator which can be promising to be easily integrated with clothing and convert the mechanical energy of human body motion into electric energy. The hybrid piezoelectric fiber comprised aligned BaTiO3 nanowires and PVC polymer. The PVC polymer made the fiber be enough flexible for performing the woven process and the aligned BaTiO3 nanowires enhanced the piezoelectric properties as active materials. The metal copper wires and cotton threads were woven into the fabric to construct the nanogenerator with interdigited electrodes. By attaching the fabric nanogenerator on an elbow pad which was bended by human arms, the nanogenerator can generate 1.9 V output voltage and 24 nA output current and the output are large enough to power a LCD.Textual abstract: Wearable nanogenerators are vital important for wearable devices and portable electronic devices. Here we report a flexible hybrid piezoelectric fiber based two-dimensional fabric nanogenerator which can be promising to be easily integrated with clothing and convert the mechanical energy of human body motion into electric energy. The hybrid piezoelectric fiber as active materials comprised aligned BaTiO3 nanowires and PVC polymer. The metal copper wires and cotton threads were woven into the fabric to construct the nanogenerator with interdigited electrodes. By attaching the fabric nanogenerator on an elbow pad which was bended by human arms, the nanogenerator can generate 1.9 V output voltage and 24 nA output current and the output are large enough to power a LCD.

•<001> Oriented BaTiO3 nanowires were successfully assembled in PVC polymer to form high-strength piezoelectric microfiber via spinning technique.•The reinforced mechanism of output performance of the fiber was studied and analyzed.•A flexible single fiber based wearable nanogenerator was fabricated and demonstrated the energy harvesting of human body motion.A super flexible nanogenerator based on BaTiO3 nanowires- polyvinyl chloride(PVC) composite single fiber was reported. The fabricating process of the nanogenerator consists of three main steps. In the first step, the <001> oriented BaTiO3 nanowires are prepared by topochemical synthesis. Secondly, the BaTiO3 nanowires-polymer composite fibers were fabricated by spinning method, and the BaTiO3 nanowires with high aspect ratio were assembled into PVC matrix to form composite fibers. The shearing stress during the spinning process make the BaTiO3 nanowires uniformly align along the fiber. Finally, BaTiO3 nanowire-polymer composite fibers were transferred onto a receiving substrate which has been covered with interdigital electrodes previously by ink-printing. The single highly <001> oriented BaTiO3 nanowire-polymer fiber based nanogenerator (SFBNG) demonstrated an output voltage up to 0.9 V and an output current up to 10.5 nA when the nanogenerator was fixed on human finger and the finger was bended. This research opens up the path for improve the robustness and output performance of wearable, especially textile nanogeneragtors.A single fiber–based nanogenerators present a good performance as wearable device for harvesting the energy of human movement. The spinning process makes the BaTiO3 nanowires aligned in the PVC matrix. The superior performance of the single fiber–based nanogenerator (SFBNG) may be attributed to both the high piezoelectric constant and the mechanical property. A maximum output voltage of 0.9V and output current of 10.5nA were obtained from the SFBNG when it bending by the finger movement. The enhanced performance, the flexibility and ultrahigh tensile strength of the composite fiber make it a promising materials for energy harvesting as wearable generators.

The CaCu3Ti4O12 ceramics were sintered in air and pure O2 atmosphere, respectively, and the effect of pure O2 atmosphere on the electrical behavior of the CaCu3Ti4O12 ceramics was investigated. It was found that the dielectric properties of the CaCu3Ti4O12 ceramics displayed a Debye-like relaxation between 20 Hz and 1 MHz, but the permittivity of the sample sintered in pure O2 atmosphere was decreased drastically. Moreover, the I–V behavior of the ceramic sintered in pure O2 atmosphere presented a linear feature. With XPS analysis, it was illustrated that the valence of Cu and Ti elements in the CaCu3Ti4O12 ceramics had obviously been influenced by the O2 concentration. Based on the experimental comparison of CaCu3Ti4O12 ceramics sintered in air and pure O2 atmosphere, it was suggested that the valence of metallic elements and defects played key role for the origin of the giant permittivity and I–V nonlinear feature in the CaCu3Ti4O12 ceramics.

The effects of Sr doping on the dielectric properties and current–voltage nonlinear behavior of CCTO were investigated. By combining the observations of dielectric properties, current–voltage nonlinearity and impedance spectroscopy, we have found that Sr doping has influenced the electrical properties by adjusting the impedance characteristics of the grain and grain boundary. Among the Sr-CCTO specimens in this work, as Sr doping concentration is 10%, the specimen (Sr-CCTO-2) has the highest permittivity and lowest nonlinear coefficient.

A high output flexible piezoelectric generator based on a highly oriented BaTiO3 film self-assembled using an interfacial strategy is reported. We have successfully controlled the morphology and orientation of BaTiO3 particles and obtained a BaTiO3 film using a facile interfacial self-assembled method. The BaTiO3 film is transferred onto an ITO coated PET substrate and packaged with PDMS (polydimethylsiloxane) to form a flexible piezoelectric energy harvesting device. The interfacial assembling strategy can effectively increase the volume fraction of active piezoelectric materials in composite films. The BaTiO3 film-based piezoelectric generator was demonstrated to harvest wind energy by employing a windmill and the output power was large enough to light a LCD.