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This brief presents a high voltage modular supply multiplying pulser in a 0.18- $\mu m$ BCD CMOS process. Two prototypes of the pulser were implemented for target loads of 55pF and 1nF, and generated up to 1MHz and 28.7V pulse from 1.2 and 5V supplies. Proposed modular based stepwise pulse generation achieved a peak power reduction of 75.4% relative to CV 2 f and a peak power efficiency of 82.3%. The proposed pulser was used for driving piezoelectric micromachined ultrasound transducer (pMUT) and achieved a relative efficiency improvement of 113.7% against conventional two-level square wave pulsing.

This study presents the fabrication and characterization of a piezoelectric micromachined ultrasonic transducer (pMUT, radius: 40 &mu, m) using a patterned aluminum nitride (AlN) thin film as the active piezoelectric material. A 20 &times, 20 array of pMUTs using a 1 &mu, m thick AlN thin film was designed and fabricated on a 2 &times, 2 mm2 footprint for a high fill factor. Based on the electrical impedance and phase of the pMUT array, the electromechanical coefficient was ~1.7% at the average resonant frequency of 2.82 MHz in air. Dynamic displacement of the pMUT surface was characterized by scanning laser Doppler vibrometry. The pressure output while immersed in water was 19.79 kPa when calculated based on the peak displacement at the resonant frequency. The proposed AlN pMUT array has potential applications in biomedical sensing for healthcare, medical imaging, and biometrics.

Underwater sensors that detect the distance and direction of acoustic sources are critical for surveillance monitoring and target detection in the water. Here, we propose an axial vector sensor that utilizes a small (~1 cm3) compressive-type piezoelectric accelerometer using piezoelectric single crystals. Initially, finite element analysis (FEA) was used to optimize the structure that comprised piezoelectric Pb(Mb1/3Nb2/3)O3-28%PbTiO3 single crystals on a tungsten seismic mass. The receiving voltage sensitivity (RVS) was enhanced through geometric optimization of the thickness and sensing area of the piezoelectric material and the seismic mass. The estimated maximum RVS of the optimized vector sensor was &minus, 212 dB. FEA simulations and practical measurements were used to verify the directivity of the vector sensor design, which exhibited a dipole pattern. The dipole beam pattern was used to obtain cardioid patterns using the simulated and measured results for comparison. The results clearly showed the feasibility of using the proposed piezoelectric single-crystal accelerometer for a compressive-type vector sensor.

Lead zirconate titanate (PZT) films grown on flexible Ni foils were utilized to explore the effects of thickness and poling conditions on the performance of mechanical energy harvesters. In the case of Mn doped 1 μ m thick (001) oriented sol-gel PZT (52/48) films on Ni foil, the dielectric constant and | e 31 , f | are 390 at 10 kHz and 11.3 C/m2, respectively, after hot poling. This film has a large figure of merit ( e 31 , f 2 e r ), of around 0.4 C2/m4, for piezoelectric energy harvesting. Unimorph cantilever beams were easily fabricated from PZT films on Ni foil using simple mechanical cutting. The maximum power increases from 12 to 60 μW as the thickness of Nb doped PZT film increases from 1 to 3 μ m at resonance frequency (∼70 Hz) at 0.5 G. The optimum poling condition (150 °C, at 3 times the coercive for 15 min) enhanced the voltage and power output of the cantilever harvester prepared using (1 μm) PZT films on Ni foil. It was found that the power performance of harvesters strongly depends on the thickness of the film with resonant harvesters of the same footprint area (0.385 cm2) using PZT films on Ni foils.

Vector hydrophones based on a micro-electro-mechanical system (MEMS) hold great promise for underwater communications, due to their potential for miniaturization and mass production. Piezoelectric materials have recently been utilized in the fabrication of MEMS-based vector hydrophones, as less power is typically required for their operation. Here, we propose a millimeter-scale piezoelectric MEMS vector sensor with a suspended cross-shaped beam and a mushroom-shaped proof mass configuration. This design was inspired by the bio-transducer of the lateral line of fish. Sensor fabrication involved piezoelectric Pb(Zr0.52Ti0.48)O3 thin-film deposition by radio-frequency magnetron sputtering onto the beam structure, followed by a multi-etching process and assembly using a three-axis microassembly technique. The fabricated MEMS vector sensor showed a resonance frequency above the working frequency range, which was suitable for naval applications. The directivity of the proposed sensor was determined by dipole patterns in the x and y directions, with a maximum relative sensitivity difference of −42 dB at 1 kHz. Finite element analysis results for the resonance frequency and directivity were in good agreement with the experimental results, suggesting that the proposed vector sensor could be used in underwater communications as a vector hydrophone.

The past few years have witnessed a growing demand for self-powered wearables that can enable vigilant health monitoring, with 24/7 operation. Energy harvesting from human-body motion is attractive for wearables; however, conventional unidirectional single-cantilever-beam piezoelectric energy harvesters (PEHs) [1]–[4] suffer from several body-motion harvesting challenges: such as multi-axial motion, irregular frequencies, and unpredictable amplitudes with frequent low-power levels [5]. To address these challenges, an eccentric rotor-based inertial PEH has been developed, which utilizes multiple magnetically plucked flexible thin-film $(60 \mu \mathrm {m})$ PZT-nickel-PZT beams to significantly increase the harvested energy within a small volume [5]; compared to bulk-PZT beams that are more feasible in direct-force-driven PEHs. The wrist-worn multi-beam PEH, shown in Fig. 27.4.1, converts multi-axial body motion into AC voltages with different phases and decaying amplitudes (up to several volts) within the frequency range of 90–160Hz for each beam.

For distributed sensing, local power sources are of interest. [...]

Piezoelectric energy harvesting from ambient vibrations offers an environmentally friendly approach to powering distributed sensors for the Internet of Things. This paper gives a direct comparison of Pb(Zr,Ti)O3 (PZT)- and (K,Na)NbO3 (KNN)-based harvesters using a compliant mechanism harvester design for resonant frequencies of 20, 40, and 70 Hz. At 70 Hz, the measured power densities for PZT- and KNN-based devices are 1139 and 31 μW/mm3, respectively, for unimorph structures on nickel foils of 25 and 50 μm in thickness. The power density ratios scale proportionally to the material energy harvesting figures of merit. Energy harvesting with the compliant mechanism design is twice as efficient when compared to harvesting with a simple cantilever beam.

Extracting energy from low vibration frequencies (

The effects of eco-friendly (BiNa0.84K0.16)0.48Sr0.04TiO3 (BNKS)-content in 0.65Bi1.05FeO3–0.35BaTiO3 (BFBT) dielectrics were investigated by following simple solid state fabrication route. By the introduction of BNKS in BFBT matrix the average grain size was significantly reduced, with relatively high dense microstructure (relative density > 94%). The BNKS-modified BFBT dielectrics demonstrated thermally-stable er (670–1005, from 30 °C to 500 °C), high Tmax (424 °C–465 °C), colossal er-max (58880–69226), and er-mid (2891–5652 ± 15%) across the broad range of temperature from 244 °C to 500 °C. At the optimum composition (x = 0.10) the temperature-dependent (30 °C–150 °C) substantially high energy-storage density (Wstore ∼ 0.81 J/cm3) and efficiency (η > 60%) in bulk ceramics were observed. The thermally-stable dielectric and energy storage properties suggest that present investigated dielectrics can be promising candidates for high temperature dielectric applications and power electronics.

A wrist-worn eccentric rotor-based energy harvester utilizing multiple magnetically plucked flower petal-shaped bimorph lead zirconate titanate (PZT) thin-film beams was designed and fabricated. The bimorph beams were formed by depositing {001} oriented PZT films up to 5.4 μm in thickness on both sides of a 50 μm thick nickel foil. The prototype was characterized with an analytical system-level model and a bench-top swing-arm test set-up. The prototype can achieve approximately 40 μW power output from a bench-top pseudo walking motion input. Further simulation suggests that improvement can be made by growing thicker PZT layers.

Energy harvesting from human motion addresses the growing need for self-powered wearable health monitoring systems which require 24/7 operation. Human motion is characterized by low and irregular frequencies, large amplitudes, and multi-axial motion, all of which limit the performance of conventional translational energy harvesters. An eccentric rotor-based rotational approach originally used in self-winding watches has been adopted to address the challenge. This paper presents a three-dimensional generalized rotational harvester model that considers both linear and rotational excitations. A hypothetical power upper bound for such architectures derived using this generalized model demonstrated the possibility for harvesting significantly more energy compared to existing devices. A wrist-worn piezoelectric rotational energy harvester was designed and fabricated attempting to narrow this gap between existing devices and the theoretical upper bound. The harvester utilizes sputtered bimorph PZT/nickel/PZT thin-film beams to accommodate the need for both flexibility and high piezoelectric figure of merit in order to realize a multi-beam wearable harvester. The prototype was characterized using a bench-top swing arm set-up to validate the system-level model, which provides many degrees of freedom for optimization.

Piezoelectric energy harvesters typically perform poorly in the low frequency, low amplitude, and intermittent excitation environment of human movement. In this paper, a piezoelectric compliant mechanism (PCM) energy harvester is designed, modeled, and analyzed that consists of a PZT unimorph clamped at the base and attached to a compliant mechanism at the tip. The compliant mechanism has two flexures that amplify the tip displacement to produce large motion of a proof mass and a low frequency first mode with an efficient (nearly quadratic) shape. The compliant mechanism is fabricated as a separate, relatively rigid frame with flexure hinges, simplifying the fabrication process and surrounding and protecting the PZT unimorph. The bridge structure of the PCM also introduces an axial tensioning nonlinearity that self-limits the response to large amplitude impacts, improving the robustness of the device. Comparing the time domain performance based on realistic wrist acceleration data, the PCM produces 6 times more average power than a proof mass cantilever with the same unimorph area and natural frequency.Copyright © 2015 by ASME

In this study, a flexible magnetoelectric (ME) heterostructure of PZT/Ni was fabricated by depositing a (001) oriented Pb(Zr0.52Ti0.48)O3 (PZT) film on a thin, flexible Ni foil buffered with LaNiO3/HfO2. Excellent ferroelectric properties and large ME voltage coefficient of 3.2 V/cm⋅Oe were realized from the PZT/Ni heterostructure. The PZT/Ni composite’s high performance was attributed to strong texturing of the PZT film, coupled with the compressive stress in the piezoelectric film. Besides, reduced substrate clamping in the PZT film due to the film on the foil structure and strong interfacial bonding in the PZT/LaNiO3/HfO2/Ni heterostructure could also have contributed to the high ME performance of PZT/Ni.

The development of self-powered wireless microelectromechanical (MEMS) sensors hinges on the ability to harvest adequate energy from the environment. When solar energy is not available, mechanical energy from ambient vibrations, which are typically low frequency, is of particular interest. Here, higher power levels were approached by better coupling mechanical energy into the harvester, using improved piezoelectric layers, and efficiently extracting energy through the use of low voltage rectifiers. Most of the available research on piezoelectric energy harvesters reports Pb(Zr,Ti)O3 (PZT) or AlN thin films on Si substrates, which are well-utilized for microfabrication. However, to be highly reliable under large vibrations and impacts, flexible passive layers such as metal foil with high fracture strength would be more desirable than brittle Si substrates for MEMS energy harvesting. In addition, metallic substrates readily enable tuning the resonant frequency down by adding proof masses. In order to extract the maximum power from such a device, a high level of (001) film orientation enables an increase in the energy harvesting figures of merit due to the coupling of strong piezoelectricity and low dielectric permittivity. Strongly {001} oriented PZT could be deposited by chemical solution deposition or RF magnetron sputtering and ex situ annealing on (100) oriented LaNiO3 / HfO2 / Ni foils. The comparatively high thermal expansion coefficient of the Ni facilitates development of a strong out-of-plane polarization. 31 mode cantilever beam energy harvesters were fabricated using strongly {001} textured 1∼3 μm thick PZT films on Ni foils with dielectric permittivity of ∼ 350 and low loss tangent (

BiFeO3-Bi(Zn1/2Ti1/2)O3 (BF-BZT) ceramics were made by a solid state reaction method. Crystal structure and microstructure were observed. Leakage currents were much reduced with BZT doping in BF. Dielectric constants of BF-BZT increased as frequency is decreased. Two distinctive relaxations were observed at about 500 kHz and 3 Hz. Ferroelectriclike hysteresis loops were observed in BF with low electric field and 2.5 and 5 mol % BZT doped ceramics.

Optimum compositions for piezoelectric properties of ceramics were investigated in the range of $x

Nb was doped to Pb-free (BNT) by a solid state mixing process to form $(Bi_{0.5}Na_{0.5})Ti_{1-x}Nb_xO_3\;(x