Bistable Generator Research Articles

A comparative analysis of parallel SSHI and SEH for bistable vibration energy harvesters

The present work focuses on ambient vibration energy harvesting. Specifically, this article deals with bistable piezoelectric energy harvesters (PEHs) which exhibits a wider bandwidth than linear oscillators. These complex systems require an energy extraction circuit (EEC) to rectify their voltage to supply power to autonomous sensors. This EEC needs to be optimized in order to increase the harvested power and even the bandwidth of PEHs. Because of the complex dynamics of bistable PEHs, there is a lack of simple and physically-insightful models in the literature that would allow the understanding and optimization of the extraction circuit. To address this issue, the present work derives closed-form models of a bistable PEH coupled to a passive and an active synchronous EEC: respectively the standard energy harvesting (SEH) circuit and the parallel synchronized switch harvesting on inductor (P-SSHI) circuit. Experimental measurements conducted on a custom bistable PEH demonstrate the validity of the proposed models with a relative error lower than 15% on the harvested power and the bandwidth. The proposed models allow to easily understand the influence of the P-SSHI circuit on the dynamics of a bistable PEH. Moreover, a comparison of the performance of the SEH and the P-SSHI circuits, valid for any bistable generator, is proposed. The latter shows that under low electromechanical coupling and low acceleration amplitude the P-SSHI circuit leads to multiply the maximum harvested power up to 4.3 compared to the SEH circuit, and the bandwidth by a factor of 2.3.

Plasmon-modulated bistable second-harmonic generation in a nonlinear microcavity coupled to a metallic nanoparticle

Multiple nonlinear effects with second-harmonic (SH) generation and optical bistability (OB) are highly desired but rather rare due to insufficient intrinsic nonlinearity in most nonlinear media. Here, a nonlinear microcavity coupled to a metallic nanoparticle (MNP) is suggested to realize the bistable SH generation. When two counterpropagating driving fields are injected into the cavity, a traditional SH pathway is constructed via the two-photon process of fundamental-harmonic (FH) photons. In addition, we report the coexistence between the SH and OB effects under the condition that the strong excitation and the detuning management for the driving fields boost system nonlinear responses. In the presence of a control field toward the MNP, our calculation finds that the traditional and plasmon-induced SH pathways in the present system allow enhancing the SH conversion efficiency and reducing the OB thresholds simultaneously. With the control field intensity increasing, a linear growth rate for the SH efficiency maximum is achieved. Furthermore, the relative phase between the driving and control fields has profound effects on modulating the bistable SH efficiency, the bistable interval and the thresholds.

Bi-stable electromagnetic generator with asymmetrical potential wells for low frequency vibration energy harvesting

Efficient energy harvesting from low and broadband frequency has always been a challenging problem. This paper proposes a solution in the form of an electromagnetic bi-stable vibration energy harvester (BVEH) with asymmetric potential barriers, in which the vibrator is attracted to the top magnet and repelled from the bottom magnet. By combining a magnetic spring and a mechanical spring, the BVEH achieves bi-stability with asymmetric potential barriers, enabling large amplitude vibration as the vibrator travels between the two potential wells. The traditional magnetic force model is modified to establish an electromechanical coupling model that accurately predicts the output of the BVEH. Numerical simulation results solved by the Runge-Kutta method show good agreement with experimental results. In addition, a prototype is fabricated and the system parameters are adjusted to achieve high-energy oscillation at the lowest frequency of 4 Hz. Under a sinusoidal excitation with an amplitude of 4 mm, the BVEH's bandwidth is expanded to 6 Hz, and the maximum power can reach 72.76 mW. Finally, the feasibility of the BVEH is demonstrated by powering different electrical appliances. The study provides a new technical approach for energy harvesting under low and broadband frequency vibration excitation.

Analysis and Application of a New S-Type Bistable Generator Beam in Energy Harvester Featured in Reducing Stress Concentration

This paper presents a newly designed bistable S-type generator beam. For two typical energy harvesting scenarios in a low-frequency excitation environment (up-and-down vibration excitation and wind-induced vibration excitation), two kinds of energy harvesting devices are designed using this S-type generator beam and tested and analyzed, respectively. The results indicate that the S-type generator beam can make full use of materials to avoid premature fatigue failure caused by stress concentration. The peak stress of the S-type generator beam is 34.3% lower than that of the cantilever beam under the same excitation conditions. Furthermore, when the environmental excitation frequency is equal to the third natural frequency (3rd mode, 7.45 Hz) of the generator beam, the motion process of the beam surpasses the potential energy barrier and generates inter-well movement (snap-through). The peak output voltage in the two different environments is 14,350 mV and 17,630 mV, respectively. Additionally, the optimal external resistance of the circuit was determined to be 22 kΩ, with a power output of the energy collector of 0.534 mW and 0.545 mW, respectively.

Bistable programmable origami based soft electricity generator with inter-well modulation

Kresling origami features an axial compression and torsion coupled motion mechanism. The nonlinear stiffness is generated by this unique deformation mode, allowing Kresling origami to be employed in wave propagation control, mechanical storage devices, digital computing, and soft robotics. In this paper, a soft bistable electricity generator is developed based on Kresling origami. This soft electricity generator is capable of initiating inter-well motion for broadband energy harvesting at low frequency and low amplitude excitation based on delicately designed structural parameters, programmable bistable energy landscape and soft origami structure fabrication. Two asymmetric potential energy wells are obtained through combining the elastic potential energy of the origami structure with the gravitational potential energy of top mass. The prototype of the bistable Kresling origami structure is fabricated by a two-step mold procedure and the theoretical model is verified through quasi-static and dynamic experiments. The number of the stable states is tunable and the energy curve is programmable by varying the top mass, initial height hs and initial torsional angle. The nonlinear bistable origami has complex dynamic phenomena such as intra-well motion, inter-well motion and chaotic motion. Compared with intra-well motion, the harvested power of inter-well motion is increased by 18.5 times. The origami structure can be excited to the inter-well orbit under low intensity excitation of 0.19 m/s2 and low frequency of 2.5 Hz. An origami-based shoe pad is fabricated by integrating the origami generator into the shoe pad to not only harvest the energy but also measure the gait and motion information from the human motions. The proposed soft electricity generator of bistable programmable origami provides a competitive solution for broadband energy harvesting under low excitation acceleration and low frequency environment, i.e., human motion and bridge vibration, showing the great potential as power supply for wearable devices and bridge monitoring devices.

Autonomous shock sensing using bi-stable triboelectric generators and MEMS electrostatic levitation actuators

This work presents an automatic threshold shock-sensing trigger system that consists of a bi-stable triboelectric transducer and a levitation-based electrostatic mechanism. The bi-stable mechanism is sensitive to mechanical shocks and releases impact energy when the shock is strong enough. A triboelectric generator produces voltage when it receives a mechanical shock. The voltage is proportional to the mechanical shock. When the voltage exceed a certain level, the initially pulled-in microelectromechanical system (MEMS) switch is opened and can disconnect the current in a safety electronic system. The MEMS switch combines two mechanisms of gap-closing (parallel-plate electrodes) with electrostatic levitation (side electrodes) to provide bi-directional motions. The switch is initially closed from a small bias voltage on the gap-closing electrodes. The voltage from the bi-stable generator is connected to the side electrodes. When the shock goes beyond a threshold, the upward force caused by the side electrodes on the switch becomes strong enough to peel off the switch from the closed position. The threshold shock the system can detect is tunable using two control parameters. These two tuning parameters are the axial force on the bi-stable system (clamped-clamped beam) and the bias voltage on the MEMS switch (gap-closing electrodes). The actuation in macro-scale is thus directly connected to a sensor-switch mechanism in micro-scale. This chain makes an autonomous actuation and sensing stand-alone system that has potential application on air bag deployment devices and powerline protection systems. We provide a theoretical frame work of the entire system validated by experimental results.

Parametric analysis for optimized piezoelectric bistable vibration energy harvesters

This study focuses on vibration energy harvesting with piezoelectric bistable inertial generators in order to provide an alternative or a support to chemical batteries in the power supply of isolated wireless sensors (leading to a better autonomy of these devices). The objective of the present work is to provide guidelines to optimize this kind of generator through the investigation of the influence of different parameters (load resistance, mass, stiffness, buckling level) on its frequency response. These guidelines will be obtained exploiting a new analytical model for piezoelectric bistable harvesters which will be constructed based on a recent model introduced for electromagnetic bistable harvesters. This model includes the study of subharmonic behaviors which can be used to enhance the global bandwidth of the harvester as well as a stability robustness criterion which allows a better prediction of experimental observations. The new model will be validated by experimental data and finally exploited to provide guidelines for piezoelectric bistable harvester optimization.

Characteristics of noise-induced intermittency

We reveal the main characteristics of noise-induced intermittency in a dynamical system with two coexisting attractors. Both the residence time distributions and the mean residence time versus an asymmetry parameter, are found analytically, for each of the coexisting states, and both of them obey exponential laws. The proposed theory is applied to a bistable energy model, dissipatively coupled logistic maps and bistable Chua generator.

MEMS electret energy harvester with embedded bistable electrostatic spring for broadband response

A MEMS electret vibration energy harvester with an embedded bistable electrostatic spring for broadband response is proposed. By using a vertical electret, the bistable potential can be realized without any complex structure or additional mechanism. Based on the 1D electrostatic model, a rigorous electromechanical model as well as an approximate model with reduced parameters are developed. Based on the normalized expression of the approximate model, which is identical to the velocity-damped resonant generator model, the performance of harvesters with the proposed mechanism has been characterized in detail for harmonic excitation, band-limited white noise, and colored noise. In addition, its performance has been compared with that of a conventional duffing-type bistable generator. It is confirmed that the present mechanism has advantages such as a lower frequency range, and outperforms the duffing counterpart for colored noise.

Drastic bandwidth enhancement of bistable energy harvesters: Study of subharmonic behaviors and their stability robustness

In order to provide a serious alternative to chemical batteries for the energy supply of isolated sensors, bistable generators have been enthusiastically highlighted in recent years for their ability to harvest vibration energy over a wider frequency range compared to linear generators. Nevertheless, these bistable harvesters are generally characterized through a frequency sweep which does not reveal all the steady-state behaviors they can reach and therefore their full energy harvesting potential. Among such behaviors, subharmonic motions are hidden by this classical characterization and therefore had not received a lot of attention. This study proposes an original complete analytical analysis of subharmonic orbits for energy harvesting to predict their contribution to the global bandwidth of bistable generators. In addition, a new criterion, referred as stability robustness, is introduced to estimate the sensitivity of those behaviors to disturbances of different levels, allowing to finely and accurately estimate suitable behaviors for energy harvesting purposes in realistic conditions (behaviors easy to reach and maintain in time). Experimental results conducted with a buckled beam based electromagnetic generator confirm the relevance of this criterion showing good agreement with the analytical predictions. Subharmonic behaviors finally appear, both theoretically and experimentally, to be of significant interest, as exploiting them leads to a 180% increase of the global operating frequency range of the considered bistable energy harvester, for which more than 100 µW are generated on a 70 Hz bandwidth at 0.5 g.

Plasmon-modulated bistable four-wave mixing signals from a metal nanoparticle-monolayer MoS2 nanoresonator hybrid system

We present a study for the impact of exciton-phonon and exciton-plasmon interactions on bistable four-wave mixing (FWM) signals in a metal nanoparticle (MNP)-monolayer MoS2 nanoresonator hybrid system. Via tracing the FWM response we predict that, depending on the excitation conditions and the system parameters, such a system exhibits ‘U-shaped’ bistable FWM signals. We also map out bistability phase diagrams within the system’s parameter space. Especially, we show that compared with the exciton-phonon interaction, a strong exciton-plasmon interaction plays a dominant role in the generation of optical bistability, and the bistable region will be greatly broadened by shortening the distance between the MNP and the monolayer MoS2 nanoresonator. In the weak exciton-plasmon coupling regime, the impact of exciton-phonon interaction on optical bistability will become obvious. The scheme proposed may be used for building optical switches and logic-gate devices for optical computing and quantum information processing.

Exploiting bistable oscillator subharmonics for magnified broadband vibration energy harvesting

Recent research on primary battery alternatives for supplying autonomous wireless devices has recently highlighted the advantages of nonlinear oscillators' dynamics and more particularly bistable oscillators' behavior for ambient vibration harvesting. The key property of bistable oscillators compared to linear ones is their enhanced operational frequency bandwidth under harmonic excitation, potentially leading to a better adaptation to the environment. However, the classical frequency response characterization of such devices does not reveal all the possible dynamic behaviors offered by bistable oscillators. Thus, subharmonic motions are experimentally investigated in this letter, and their energy harvesting potential as well as their ability to enhance the bistable generator bandwidth is evaluated. The results obtained with a generator integrating buckled beams for the bistability feature show that, in addition to the commonly considered harmonic behavior, subharmonics allow widening of the useful operating frequency band of the bistable microgenerator by 180% compared to the sole exploitation of the first harmonic motion.

Core signalling motif displaying multistability through multi-state enzymes.

Bistability, and more generally multistability, is a key system dynamics feature enabling decision-making and memory in cells. Deciphering the molecular determinants of multistability is thus crucial for a better understanding of cellular pathways and their (re)engineering in synthetic biology. Here, we show that a key motif found predominantly in eukaryotic signalling systems, namely a futile signalling cycle, can display bistability when featuring a two-state kinase. We provide necessary and sufficient mathematical conditions on the kinetic parameters of this motif that guarantee the existence of multiple steady states. These conditions foster the intuition that bistability arises as a consequence of competition between the two states of the kinase. Extending from this result, we find that increasing the number of kinase states linearly translates into an increase in the number of steady states in the system. These findings reveal, to our knowledge, a new mechanism for the generation of bistability and multistability in cellular signalling systems. Further the futile cycle featuring a two-state kinase is among the smallest bistable signalling motifs. We show that multi-state kinases and the described competition-based motif are part of several natural signalling systems and thereby could enable them to implement complex information processing through multistability. These results indicate that multi-state kinases in signalling systems are readily exploited by natural evolution and could equally be used by synthetic approaches for the generation of multistable information processing systems at the cellular level.

Optimization study of a piezoelectric bistable generator with doubled voltage frequency using harmonic balance method

Bistable generator for vibration energy harvesting is one of the most promising solutions to reach practically enhanced performance. Due to the buckled–spring–mass–specific behavior, the deformation of the piezoelectric transducer is nonlinearly dependent on the displacement, especially in the inter-well motion case. An analytical model is developed using harmonic balance analysis for the buckled–spring–mass generator architecture. Contrary to the usual method, a special doubled frequency voltage solution in the inter-well motion case is assumed in harmonic balance analysis to obtain an accurate predictive model, which is validated by experimental results. The influence of five critical parameters on the performance is thoroughly discussed. Design rules are then deduced: low damping ratio, properly high coupling level, matched load, optimal buckling level, and low characteristic frequency are required to get optimal performance in the inter-well motion case. Besides, we show some interesting results about the parameter optimization study.

Modulating the bistable potential energy separatrix for augmented broadband vibration energy harvesting

In recent years, increased interest in broadband vibration energy harvesting schemes has been a main topic of interest among researchers. One of the most successful approaches toward broadband vibration energy capture has been with bistable inertial generators. These devices leverage a nonlinear restoring force to exploit the hardening spring response to increase the resonant frequency bandwidth beyond the characteristically narrowband resonant frequency associated with conventional linear inertial generators. However, one issue with bistable energy harvesters is the presence of low-amplitude oscillations whose energy is insufficient to overcome the potential energy separatrix barrier between the competing potential wells. This article presents the effects of controlling the magnitude of the potential energy separatrix by means of a high-permeability electromagnet in order to increase the resonant response bandwidth for low-amplitude harmonic excitations. An analytical model of the bifurcation space resulting from two control parameters is presented along with an experimental validation study. Finally, an open-loop control law is developed and tested to validate the resonant frequency bandwidth augmentation for harmonic chirp excitations.

ALL-OPTICAL HYSTERESIS SWITCHING USING MOBIUS CONFIGURATION MICRORING RESONATOR CIRCUIT

The novel twisted ring resonator called add-drop Mobius microring resonator is introduced and modelled with the analytical solution of transfer matrix methods for the generation of optical bistability. Simulated results show that, the add-drop Mobius configuration provides greater phase shift due to the longer length of propagation per roundtrip than add-drop filter configuration. In add-drop Mobius system, drop port generated the optical bistable hysteresis loop with 19.25 mW output switching power and through port generated lower switching power as 5.55 mW. The drop port of the system is found as the suitable port for the operating the all-optical hysteresis switching.

Dynamic Modeling and Output Characteristic Analysis of a Micro Bistable Piezoelectric Generator

For effectively harvesting the broadband and low-frequency vibration energies in real environment, a micro bistable piezoelectric generator, without containing magnet, is designed. On the basis of analysis the nonlinear behavior of the stiffness, damping and the electromechanical coupling coefficient about the bistable vibration system, a precise mechanical-electric transfer model is built. The output characteristic of the piezoelectric generator is simulated and tested. The results showed that the piezoelectric generator can effectively harvest the broadband and low frequency vibration energies. And the output voltage can meet the electricity demand of a wireless sensor network node. The structure of the piezoelectric generator does not contain magnets, and it is easy to realize miniaturization and integration.

A wideband integrated piezoelectric bistable generator: Experimental performance evaluation and potential for real environmental vibrations

Bistable generators have been proposed as potential solutions to the challenge of variable vibration frequencies. This article presents a novel mono-block design of bistable generator based on mechanical buckling effect. A bistable structure composed of four thin beams as flexible hinges, two amplified piezoelectric stacks as electromechanical springs, and a dynamic mass is fabricated. Its volume is 5.46 cm3, and it reaches a power density of 0.48 mW/cm3. The wideband and high-power energy harvesting properties are first validated using chirp excitations with an obtained bandwidth of 11 Hz (812% improvement compared with the linear equivalent case). The generator’s good performance is then further confirmed for bandlimited noise excitations and a real vibration signal from a driving car wheel.

Self-powered nonlinear harvesting circuit with a mechanical switch structure for a bistable generator with stoppers

Energy harvesting is considered as one of the most promising solution for the power supply of autonomous sensor systems. Two main properties are required: self-powered ability and wideband operation. This article proposes a new self-powered bistable generator which is composed of three parts: the self-powered OSECE (Optimized Synchronous Electric Charge Extraction) circuit, the BSM (buckled-spring-mass) oscillator and two stoppers. The combination of the BSM oscillator and the stoppers allows wideband harvesting capability and the self-powered OSECE circuit with mechanical switches ensures high harvested power and autonomous features. A model of this novel generator is detailed and experimentally validated. As an incremental innovation, better performance is obtained for this new generator compared with the original BSM generator with the standard circuit (without stoppers and mechanical switches). Discussions and optimizations are performed to find the optimal parameters and fully investigate the performance of the proposed generator. It shows that introducing the stoppers and the self-powered OSECE circuit using mechanical switches can substantially enhance the harvested power with moderate additional complexity.

Integrated bistable generator for wideband energy harvesting with optimized synchronous electric charge extraction circuit

Bistable generators have been proposed as potential solutions to the challenge of variable vibration frequencies. In the authors' previous works, a specific BSM (Buckled-Spring-Mass) harvester architecture has been suggested. It presents some properties of interests: simplicity, compactness and wide bandwidth. Using a normalized model of the BSM generator for design and optimization at different scales, this paper presents a new integrated BSM bistable generator design with the OSECE (Optimized Synchronous Electric Charge Extraction) technique which is used for broadband energy harvesting. The experimental results obtained from an initial prototype device show that the BSM generator with the OSECE circuit exhibits better performance for low coupling cases or reverse sweep excitations. This is also confirmed by simulations for the proposed integrated generator. Good applications prospective is expected for the bistable generator with the nonlinear OSECE circuit.