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Piezoelectric energy harvester (PEH) arrays are practical solutions to the low and unreliable power output of a single PEH. However, most PEH circuits are developed for addressing the one-channel ac input from a single PEH. In this article, an extensible rectifier-less synchronized switch harvesting on inductor (ReL-SSHI) array interface with the maximal power point tracking (MPPT) function to manage the multiple ac inputs from the PEH arrays is designed. The ac–dc conversion is performed by the ReL-SSHI topology with passive peak switches featured with self-powered characteristic and fast cold-start. Only one shared inductor is employed, greatly reducing the circuit volume and cost. The MPPT module for each channel is implemented by a simple envelope detector and an ultra-low power hysteresis controller and achieves continuous energy extraction by adapting the fractional normal-operation voltage method. A developed discrete array interface able to handle three PEHs effectively executes the MPPT for each channel with the uphill and downhill response speeds of 2.0 and 7.1 V/s, and a maximal MPPT efficiency of 97.1%. This circuit boosts the power output by 485% compared with that by the traditional full-bridge rectifier, around 33% higher than that from existing synchronous electric charge extraction array interfaces. [ABSTRACT FROM AUTHOR]

Piezoelectric energy harvester (PEH) arrays are promising in many application scenarios. However, few interface circuits have been developed to manage the multiple ac inputs from PEHs. This article proposes an extensible parallel synchronized switch harvesting on inductor array interface scheme to realize a multiinput conversion from PEH arrays. We develop a split-inductor-capacitor topology that can extract electrical energy from multiple PEHs. The proposed circuit topology effectively handles the inductor access conflict in the cases of PEHs with close, identical, and opposite vibration phases, insensitive to ac input phase changes. For demonstrating the capability of dealing with multiple ac inputs from PEHs and the enhancement effect on power output, we construct and test a self-powered three-channel array circuit with the passive peak detection function. Excited by sinusoidal vibrations, our circuit effectively avoids the energy return and efficiently achieves the power combination of the three PEHs. Compared with the classic full-bridge circuit, the proposed circuit helps increase the power output by 4.8 times. Also, to show the universality of the circuit, the circuit's operation under various excitations istested and analyzed. [ABSTRACT FROM AUTHOR]

[Display omitted] Bulk piezoceramics are widely used and functional materials, but they are hard to be shaped to adapt to complex 3D surfaces. Most existing ceramic shaping techniques, like 3D printing, come at the cost of physical properties such as piezoelectricity and thermal stability. Here to fabricate 3D piezoceramic sheets, we report a mold-assisted sintering (MAS) method that can replicate 3D surfaces with nonzero Gaussian curvatures while maintaining the intrinsic properties. Assisted with supporting molds, the MAS exploits elastic-to-viscous transition of piezoceramic powder compacts during sintering, bypassing the boundaries of deformation and surface development in an elastic continuum. We successfully replicate shapes to sintered lead zirconate titanate (PZT) ceramics from designed molds with saddle, sine and spherical surfaces, respectively. The PZT ceramic replicas show high piezoelectricity and excellent conformability towards nonplanar surfaces (maximum deviation 90 μm). We further demonstrate the advantage of the conformal curved piezoceramics by using them for wirelessly transferring power over a pipeline. The MAS method is low-cost, simple, scalable and applicable to various 3D energy transducers. [ABSTRACT FROM AUTHOR]

To merge the gap between the low-power output of piezoelectric energy harvesters (PEHs) and the high-power demand of sensors of Internet of Things, researchers recently start to explore PEHs arrays. However, few circuits have been developed to manage the multiple ac inputs from PEHs arrays. This article presents a self-powered PEH array interface circuit based on the synchronized switching and discharging to a storage capacitor through an inductor (SSDCI) technique. The array interface can output a maximum total power greater than the sum of each individual peak power, and achieve a high efficiency when multiple PEHs connect to the SSDCI array circuit. Simulation and experiment are performed to demonstrate the advantages of the SSDCI array interface. The tested results show that the designed SSDCI array circuit achieves an efficiency of 82.3% with three input sources, and allows a gain up to 300% in terms of maximal output power compared to the full-bridge rectifier. In addition, only the peak detection is utilized for the switching control; therefore, the SSDCI array circuit is realized more easily and with fewer components compared to the existing synchronous electric charge extraction array interfaces. [ABSTRACT FROM AUTHOR]

Highlights: Freestanding lead-free piezoceramic thin films can be derived via water peeling. The d33 value of the freestanding BCZT thin film reaches 209 pm V−1. The freestanding piezoceramic films obtain versatile application scenarios such as energy harvest and virus detection. Most electronics such as sensors, actuators and energy harvesters need piezoceramic films to interconvert mechanical and electrical energy. Transferring the ceramic films from their growth substrates for assembling electronic devices commonly requires chemical or physical etching, which comes at the sacrifice of the substrate materials, film cracks, and environmental contamination. Here, we introduce a van der Waals stripping method to fabricate large-area and freestanding piezoceramic thin films in a simple, green, and cost-effective manner. The introduction of the quasi van der Waals epitaxial platinum layer enables the capillary force of water to drive the separation process of the film and substrate interface. The fabricated lead-free film, Ba 0.85 Ca 0.15 Zr 0.1 Ti 0.9 O 3 (BCZT), shows a high piezoelectric coefficient d33 = 209 ± 10 pm V−1 and outstanding flexibility of maximum strain 2%. The freestanding feature enables a wide application scenario, including micro energy harvesting, and covid-19 spike protein detection. We further conduct a life cycle analysis and quantify the low energy consumption and low pollution of the water-based stripping film method. [ABSTRACT FROM AUTHOR]