Piezoelectric energy harvesters have proven to have the potential to be a power source in a wide range of applications. As the harvester dimensions scale down, the resonance frequencies of these devices increase drastically. Proof masses are essential in micro-scale devices in order to decrease the resonance frequency and increase the strain along the beam to increase the output power. In this work, the effects of proof mass geometry on piezoelectric energy harvesters are studied. Different geometrical dimension ratios have significant impact on the resonance frequency, e.g., beam to mass lengths, and beam to mass widths. A piezoelectric energy harvester has been fabricated and tested operating at a frequency of about 4 kHz within the audible range. The responses of various prototypes were studied, and an optimized T-shaped piezoelectric vibration energy harvester design is presented for improved performance.

This paper aims at comparing micromachined cantilever structures with the purpose of providing design guidelines towards high performance energy harvesters such that they provide a good output power, resonant frequency and volume trade-off, while considering microfabrication process limitations. Increasing the power output of piezoelectric energy harvesters by tapering the beams has been presented as promising solution in the literature. This paper investigates the power output of several geometric variations of cantilever beams, and examines the advantages of balancing the strain distribution throughout the beam. A comparison of the impact of different geometries is presented, and recommendations are given. Namely, eight rectangular and trapezoidal T-shaped designs are fabricated and benchmarked. Their resonant frequencies and power outputs are compared for the same available area (1800 μm× 800 μm). Measurements show that the trapezoidal designs can have a higher output power depending on the beam length to mass length ratio, in comparison to the rectangular T-designs that have lower frequencies. Resonant frequencies ranging from 2.9 to 7.2 kHz and power outputs ranging from 2.2 to 7.1 nW are reported.

This brief presents a novel level-shifter circuit for high-frequency high-voltage (HV) gate-drives. The proposed level shifter (LS) is designed based on a capacitive-coupler/current mirror/ latch structure which helps to extend operation voltage of a floating supply into the negative range, achieves sub-ns and constant delay, and consumes very low power from the floating supply. Additionally, common-mode noise cancellers based on a cross-current mirror and transmission gates are also presented to enhance the dV/dt immunity of the LS against slewing of the floating ground. Implemented in 0.18 μm HV BCD-on-SOI (bipolar-CMOS-DMOS on silicon-on-isolator) process, the post-layout simulation of the proposed design shows a delay of 680 ps, 200 V/ns of dV _SSF /dt slew rate immunity, It dissipates no static power and only 8.1 pJ/transition from the floating supply, improving FoM ¹ and FoM ² of the proposed LS by 3 times and 11.7 times compared to respective state-of-the-art works.

An eight-stage reconfigurable charge pump for microelectromechanical system (MEMS) electrostatic actuation was designed and fabricated in a standard 0.13-μm CMOS technology. The purpose of the circuit is to generate sufficient on-chip voltages that are continually reconfigurable for MEMS actuation. Small 1-pF pumping capacitors are used to reduce the circuit area. Digitally programmable voltage levels can be out putted by varying the number of stages and the clock drive levels dynamically. Reduced power consumption is achieved using a variable frequency clock. The circuit attains a measured maximum output voltage of 10.1 V from a 1.2 V supply. Its nominal clock is set to 50 MHz. The circuit has a compact area of 215 μm × 300 μm and consumes 864 μW at a 50-MHz clock and 252 μW at an 8-MHz clock.

With the rise of the Internet of Things (IoT) and the ever-increasing number of integrated sensors, the question of powering these devices represents an additional challenge. The traditional approach is to use a battery; however, harvesting energy from the environment seems to be the most practical approach. To that end, the use of piezoelectric MEMS energy has been proven as a potential power source in a wide range of applications. In this work, a proof of concept for a new architecture for MEMS energy harvesters is presented. The influence of the dimensions and different characteristics of these designs is discussed. These designs have been proven to be resilient to process variation thanks to their unique architecture. This work presents the use of vibration enhancement petals in order to widen the bandwidth of the energy harvester and provide a non-linear frequency response. The use of these vibration enhancement petals has allowed the fabrication of three design variations, each using an area of 1700 µm by 1700 µm. These designs have an operating bandwidth between 3.9 kHz and 14.5 kHz and can be scaled to achieve other targeted resonant frequencies.

In this article, a methodology for increasing the displacement of the membrane in nonlinear transducers is presented. This methodology that relies on pulse shaping is based on the frequency modulation of the excitation signal which in turn results in an amplitude modulation of the displacement of the resonator. The benefits of pulse shaping include the increase of the displacement of the membrane of the resonator, the ability to leverage two mechanisms to dynamically tune the resonant frequency of the device and a relative control of the decay time of the resonator. These properties have been verified using simulations and experimental results. The experimental results are performed using two nonlinear resonators with a frequency of 3.9 and 7.9 kHz. With a constant amplitude of the excitation voltage, experimental results show that the use of pulse shaping allows a velocity increase of the membrane of a piezoelectric microelectromechanical systems (MEMS) resonator of up to 191% for a softening type resonator (STR), and 348% for a hardening type resonator (HTR). The frequency tuning mechanism allowed the operation of the STR and of the HTR over a bandwidth of 280 and 115 Hz, respectively, while providing higher velocity than with the non-optimized excitation signal. The resulting pulse shaping methodology can be applied to other nonlinear resonators as shown using simulation and experimental results. Therefore, this work should lead to an increase of the use of nonlinear resonators for various applications.