Search

Various attempts are being carried out to convert variety of ambient energies. Every conversion mechanism has its own limitations on efficiency. In this context, piezoelectric phenomenon found to be promising over electromagnetic and electrostatic considering mechanical oscillations in to useful electrical energy. In this work, we use piezoelectric effect because it has an advantage of high converting power efficiency and ease of application. Cantilever uses piezoelectric effect to harvest energy from load. Bimorph cantilever based piezoelectric energy harvester with three different materials; PZT-5A, PZT-8 and cadmium sulfide for three different proof mass patterns 3.5 µm × 2 µm, 3 µm × 2.5 µm, 2.5 µm × 3 µm in the frequency range 60 to –90 Hz and applied load of 100 N to 100 KN has been simulated using software tool COMSOL Multiphysics v 5.2. From the analyses of simulation results, PZT-5A material-based piezoelectric energy harvester with the proof mass dimension of 3.5 µm × 2 µm was found to exhibit maximum efficiency. The reasons for such high efficiency have been discussed in detail by means of physical properties of piezoelectric materials used, range of applied load and proof mass patterns.

Harvesting energy from the human body has attracted substantial attention from industries and academics as it is a promising solution to address the battery life issue. In this paper, we developed a bimorph piezoelectric bending beam-based energy harvester to scavenge energy from the human knee motion for powering body-worn electronics such as smartwatches and health monitors. During walking, the human knee will flex and extend to periodically deform piezoelectric macro fibre composites (MFC) bounded to the bending beam thus generating electricity. The mathematical models of the whole system including the model of the large deflection of the bending beam, movement analysis of the end of the bending beam (slider-crank mechanism), the model of piezoelectric transducers, and measurement of the human knee angle are developed to comprehensively study the harvester. To validate the presented mathematical models, experimental testing on a human body when the subject walks on a treadmill at three different walking speeds is conducted here. The experimental results show good agreement with the simulation results, which indicates that the developed models can characterize the harvester. In addition, the performance of the harvester walking in different contexts is also evaluated. The average power can reach 12.79 mW for level-ground walking, 9.91 mW for stair descending, and 7.70 mW for stair ascending, when walking at a self-selected speed.

Tri-stable magneto-piezoelastic oscillators exhibit superior performance in terms of broadband resonance frequency and lower excitation threshold, compared to linear and bi-stable systems. Furthermore, inclusion of magnets renders them applicable, tunable, and simple designs. However, the potential of this oscillators for the purpose of simultaneous vibration suppression and energy harvesting has not been investigated. This study aims to investigate simultaneous energy harvesting and vibration isolation through a tri-stable magneto-piezoelastic absorber (TMPA). The absorber comprises a bimorph cantilever beam carrying a magnetic tip mass and two external magnets. The interplay between magnets generates a nonlinear restoring force in the TMPA structure. This absorber is attached to a host vibrating beam, which is under a transient or periodic forcing, in order to reduce its vibrations and harvest electrical energy. The nonlinear magneto-electromechanical equations governing the coupled system are obtained by employing the Hamilton's principle, Euler-Bernoulli beam theory, and a recently proposed magnetic force relationship. First, the mechanisms of tri-stability formation are investigated via bifurcation diagrams. Next the potency of the TMPA in the transient excitation scenario is examined. Furthermore, the performance of the TMPA in the presence of the periodic excitation with different forcing levels is investigated. Specifically, frequency and time domain analyses are carried out to characterize the response of the system and efficiency of the absorber when TMPA performs periodic in-well, aperiodic inter-well and periodic inter-well oscillations. In addition, to provide a better insight regarding the TMPA performance, the kinetic energies, harvested power, and dissipated power for the region of strongly modulated response are also studied. Moreover, the efficacy of the TMPA in periodic snap-through oscillations is examined by the means of the harmonic balance method in conjunction with pseudo-arclength continuation scheme. Finally, the results disclosed that the proposed tri-stable absorber outperforms a linear absorber in vibration annihilation and energy harvesting.

This study investigates complex acoustical intensity using a polyvinylidene fluoride (PVDF) bimorph. Analytical models of the open-circuit voltage outputs of an infinite-strip-shaped PVDF bimorph cantilever in an underwater sound field are developed. Results show that the sound pressure generates the sum of the outputs, while the particle velocity normal to the PVDF surface generates the difference. The sensitivities of the pressure- and velocity-generated voltage responses with respect to an incident plane sound field demonstrate uniform directivity in a low-frequency range, which is suitable for acoustical intensity determination. The higher velocity sensitivity confirms the advantage of using a PVDF bimorph as a velocity sensor, owing to its light weight and flexibility. An algorithm for determining the complex acoustical intensity normal to the surface is proposed by utilizing those voltage responses and the probe gain calibrated with a given angle of incident sound. This algorithm allows accurate determination of sound intensity of a plane wave field, where the reactive part of intensity is absent. However, a small error may exist when the reactive intensity is large and active intensity is small. This small discrepancy arises from the inherent variation in the phase directivity of the gains, which decrease with frequency.

Piezoelectric energy harvesting (PEH) remains a key area of interest for academic research due to its fast advancement and growing demand for low-powered electronics. In this study we have investigated various energy harvesting scenarios including PZT bimorph cantilever, circular bimorph with a fixed constraint at the center and at the perimeter, roller constraint at the center and at the perimeter, and circular unimorph disc with a fixed constraint at the center and at the perimeter, as well as a unimorph with two different dimensions. Modeling and simulation are performed in COMSOL for all scenarios starting from an aluminum shim (for stress/strain analysis) then bimorph/unimorph (for analysis of voltage/power). Samples are prepared in accordance with model analysis and tested on a custom-made experimental setup. Simulated and experimental results are compared and found to be in agreement. Surprisingly, a circular unimorph disc with a fixed constraint at the center shows the best result producing 7.1 V at 500 Hz with a broadband curve (450 Hz to 650 Hz). The PZT circular unimorph disc with the highest power density of 1.6234 mW/cm2 is found to be the most efficient variant.

In this work, Shape-memory alloy (SMA)-based micromirrors were fabricated and the actuation was controlled through thermal stimulus. The micromirrors play a significant role in scanning and light deflection in the MEMS field. The SMA micromirrors were developed by coating CuAlNi thin film on strained kapton polyimide substrate using thermal evaporation. Later patterns were made on micromirrors for transmission and reflection of the light beam during actuation. The displacement of each distinct pattern was explored at different voltages ranging from 1 to 3 V through Joule heating technique. The maximum displacement observed was 1.9 mm for deltoid-patterned micromirror at 3 V. The ladder pattern recorded the minimum deflection of 1.1 mm at 3 V. The shape recovery ratio analysis showed that deltoid pattern bimorph had the highest recovery of 1.656. Energy-Dispersive X-ray Spectroscopy (EDS) analysis showed that the composition was maintained after the deposition.

The abundant waste thermal energy from various sources can be efficiently harvested using material-based technology. Shape memory alloy (SMA) is an efficacious material-based technology for recovering waste heat. In this work, the NiTi SMA bimorph belt has been fabricated in flash evaporation equipment using a customized substrate holder setup. The SMA bimorph belt has been developed with three different prestrain percentage of 1, 3, and 5%. The kapton polyimide substrate is prestrained using a tensile testing setup before the deposition. The actuation characteristics and material characterization of this bimorph belt with varying prestrain percentages have been analyzed. The prestrained bimorph belt with superior material properties and actuation characteristics is used for harnessing the waste heat energy. The actuation performance explored through plate heating reveals 5% prestrain in the bimorph has the maximum shape recovery ratio in both butterfly and cantilever configuration. The contact-based electrical actuation (Joule heating) showed a maximum deflection of 1 mm at 5% prestrain. The adhesion and composition of the bimorph are unaltered with varying prestrain percentage. The morphology shows smooth deposition without any pores and the mechanical strength reduces with an increase in prestrain percentage. The SMA bimorph belt with 5% prestrain generated 60 rpm with aluminum hub and 45 rpm with the polylactic acid hub in the developed prototype using simulated exhaust heat condition.

In this article, near-zero drift and high electromechanical coupling acoustic resonators have been designed and demonstrated. The acoustic resonator is based on Lamb acoustic waves in a bimorph composed of lithium niobate on silicon dioxide. Our approach breaks through a performance boundary in conventional Lamb-wave resonators by introducing the bimorph while operating at higher order resonant modes. This enables the resonator to achieve frequency scalability, a low-temperature coefficient of frequency, and high electromechanical coupling altogether. The electromechanical coupling and temperature coefficient of the resonator were analytically optimized for the A3 mode through adjusting the thicknesses of different materials in the bimorph. Resonators with different dimensions and stack thickness were fabricated and measured, resulting in a temperature coefficient of frequency ranging from −17.6 to −1.1 ppm/°C, high electromechanical coupling ranging from 13.4% to 18%, and quality factors up to 800 at 3.5 GHz. The achieved specifications are adequate for fifth-generation (5G) sub-6-GHz frequency bands n77 and n78.

This paper reports a bimorph pinned piezoelectric micromachined ultrasonic transducer (PMUT) for enhanced sound pressure output and electromechanical coupling factor for space imaging applications. An equivalent circuit model has been built to analyze the dynamic behavior of PMUTs and prototype devices have been designed, fabricated. Experimental results show a 58% measured increase in the electromechanical coupling factor and pulse-echo measurements show a 4-meter traveling distance in air under a 133 kHz driving frequency. As a demonstration example, a relatively long-distance (>1.5 meters) ultrasound imaging test in air is conducted using a $4\times 4$ bimorph, pinned dual-electrode PMUTs array based on the transmission beamforming scheme. As such, this work enhances and extends the PMUT performances and capabilities for potential broad applications. [2021-0102]

Amorphous ribbons from a rapidly quenched alloy of the TiNi–TiCu quasi-binary system with copper content of 30 at % are crystallized via electric pulse treatment with variable durations of impact in the range of 1 to 100 ms at external tensile stress of up to 250 MPa. It is shown that the formed bimorph structure of columnar and coarse crystals is characterized by considerable differences when compared to a rapidly quenched alloy with 25 at % copper. An increase in tensile stress does not affect the phase composition or microstructure of the alloy, but it does lower the critical temperatures of martensitic transformation.

The actuators for precise positioning based on bimorph structures of piezoelectric LiNbO3 and LiTaO3 crystals are considered. The optimal orientations of the actuator plates ensuring the highest possible displacements are determined by the extreme surfaces technique and the finite-element method. The simulated displacements for optimal orientations of LiNbO3 and LiTaO3 plates are compared with those obtained experimentally for manufactured LiNbO3 and LiTaO3 actuators, whose orientations are not optimal. As is shown, the optimal configuration of the actuator allows us to significantly increase its displacement for both LiNbO3 and LiTaO3 specimens.

Soft electrothermal actuators have been of particular interest to researchers in soft mechatronic/robotic systems due to their large deformation, lightweight, and low power actuation. Closed-loop control of soft actuators is critical for high-precision applications, due to the nonlinear relationship between actuation voltage and output bending motion. In this article, a resistive self-sensing approach was developed for the soft electrothermal actuator, which enables the closed-loop control of the actuator without external sensors. The self-sensing of the actuator's deformation is achieved by measuring the resistance change of the embedded microfilament heater of the soft electrothermal actuator. When the bimorph electrothermal actuator deflects under the temperature change, its deflection can be detected by the temperature-incurred resistance change of the embedded heater. A closed-loop controller was designed using the self-sensed deflection signal. To handle the different responses of the actuator in the heating and cooling stages, a switching proportional-integral-derivative control algorithm was designed. Specifically, two sets of control parameters were tuned and used for the heating and cooling stages, respectively. The performance of the designed control algorithm was evaluated for step response, tracking of complex wave signals, and disturbance rejection. Compared with the open-loop operation, the closed-loop controlled actuator demonstrated a much more rapid and accurate response (the rising time and settling time were reduced over 80%) and excellent tracking and disturbance rejection capabilities.

3-D-printed structures integrated with laser-cut spiral PZT bimorphs are used to obtain low mechanical resonance frequencies for energy harvesting and a vibration-activated mechanical switch. This structure is used to realize a batteryless vibration event detector and RF transmitter, using the energy in the vibration and a mechanical switch as a comparator. The low-resonance frequency of the 3-D-printed mechanical resonators is used to supply significant mechanical resonance gain and trigger the impulse response of the PZT bimorphs, resulting in an upconversion of resonance frequencies. RF pulses are generated by an LC resonator and transmitted by a loop antenna for reporting event detection. The 3-D-printed structure has resonances as low as 17.5 to 40 Hz corresponding to the vibration energy spectrum readily available in the environment. Theory and experiments to verify RF output are presented. At 40 Hz and 0.75 g excitation, the resulting RF pulse is at a carrier frequency of 10.9 MHz with energy extracted from the bimorph of 0.95 nJ per pulse. As a demonstration of the device, the wireless sensor node is used to identify operational modes of a portable gasoline electric generator.

Soft actuators and microrobots that can move spontaneously and continuously without artificial energy supply and intervention have great potential in industrial, environmental, and military applications, but still remain a challenge. Here, a bioinspired MXene-based bimorph actuator with an asymmetric layered microstructure is reported, which can harness natural sunlight to achieve directional self-locomotion. We fabricate a freestanding MXene film with an increased and asymmetric layered microstructure through the graft of coupling agents into the MXene nanosheets. Owing to the excellent photothermal effect of MXene nanosheets, increased interlayer spacing favoring intercalation/deintercalation of water molecules and its caused reversible volume change, and the asymmetric microstructure, this film exhibits light-driven deformation with a macroscopic and fast response. Based on it, a soft bimorph actuator with ultrahigh response to solar energy is fabricated, showing natural sunlight-driven actuation with ultralarge amplitude and fast response (346° in 1 s). By utilizing continuous bending deformation of the bimorph actuator in response to the change of natural sunlight intensity and biomimetic design of an inchworm to rectify the repeated bending deformation, an inchwormlike soft robot is constructed, achieving directional self-locomotion without any artificial energy and control. Moreover, soft arms for lifting objects driven by natural sunlight and wearable smart ornaments that are combined with clothing and produce three-dimensional deformation under natural sunlight are also developed. These results provide a strategy for developing natural sunlight-driven soft actuators and reveal great application prospects of this photoactuator in sunlight-driven soft biomimetic robots, intelligent solar-energy-driven devices in space, and wearable clothing.

A nonlinear developed model for various PZT wind energy harvesters with arbitrary dimensions and location of electroceramics has been prepared. This model can describe unimorph and bimorph harvesters with different cantilever cross-sections attached to a tip body with different shapes. The system model has been validated with results reported in the literature. A set of parametric studies has been conducted to examine the influences of the cantilever shape in addition to the shape of the tip body. Furthermore, the impacts of load resistance and wind speed on the output power have been analyzed. The effects of number, position, and dimensions of piezoceramics on the harvester performance have also been investigated. It is found that by increasing the total area of electroceramics (including the length, width, or the number of PZT patches), the peak of the wind critical speed and the middle resistance range where the instability speed is very sensitive to the electrical load shifts toward the lower resistances. Moreover, several instrumental points to design efficient and affordable vibrating wind harvesters at low and high flows have been obtained.

The steady-state parametric analysis of a piezoelectric-coupled rotating tapered-bimorph system consists of a central host beam and two piezoelectric ceramic patches above and below it, tapering along positive X-direction and rotating in the X–Y plane, subjected to axial dynamic as well as static loading at its one end is done. The influence of three boundary conditions and various system parameters are also studied. The mathematical modeling of the rotating tapered-bimorph system is formulated with the help of Hamilton's equation. The parametric analysis of the axially loaded system is done for clamped-free (C-F), pinned-pinned (P-P), and clamped-pinned (C-P) boundary conditions. A number of parametric instability regions along with static buckling load plots are obtained and analyzed for various values of the piezoelectric patches to the host beam thickness ratio, taper parameter, and rotational frequency using MATLAB software and depicted through a series of diagrams. The results illustrate that the principal modal frequencies of the tapered-bimorph rotating system are increased rapidly with an increase in the thickness ratio, whereas increase less significantly with a rise in taper parameter and spinning speed for both the static and dynamic loading conditions. The lowest first modal frequency is observed for the P-P system under any given system configurations and operating conditions, which can be used for low-frequency rotational vibration energy harvester over the orthodoxly used C-F system. Designing low-frequency rotational vibration energy harvester and rotor blades can be done by selecting appropriate dimensions and parameters presented in this article.

A vibrotactile actuator driven by light energy is developed to produce dynamic stimulations for haptic rendering on a thin-film structure. The actuator is constructed by adopting a thermal bimorph membrane structure of poly(3,4-ethylenedioxythiophene) doped with p-toluenesulfonate (PEDOT-Tos) coated onto a polyethylene terephthalate (PET) film. Upon irradiation of near-infrared (NIR) light, the light energy absorbed at the PEDOT-Tos layer is converted into thermoelastic bending deformation due to the mismatch in coefficient of thermal expansion between PEDOT-Tos and PET. Since the light-induced deformation is reversible, spatially localized, and rapidly controllable with designed light signals, the proposed actuator can produce vibrotactile stimulation over 10 dB at arbitrary areas in the human-sensitive frequency range from 125 to 300 Hz using a low input power of ∼2.6 mW mm-2, as compared with a complex electrical circuit and high input power needed to achieve such actuation performance. Together with its simple structure based on light-driven actuation, the advent of this actuator could open up new ways to achieve substantial advances in rendering textures at a flexible touch interface.

This study presents the Internet-of-things (IoT) based Foot-step equipped piezoelectric sensors (F-SEPS) application, which are used for charging the mobile phone devices respectively. Genetic Algorithm, Big Bang–Big Crunch Algorithm (BB–BC) and Hybrid Big Bang Big Crunch tuned Genetic Algorithm (HBBBCGA) are the optimization techniques used for optimizing eight types of unimorph and bimorph structures (Type A-unimorph structure without proof mass, Type B-unimorph structure with proof mass at left location, Type C-unimorph structure with two proof mass and Type D-unimorph structure with three proof mass, Type E-bimorph structure without proof mass, Type F-bimorph structure with proof mass at left location, Type G-bimorph structure with two proof mass and Type H-bimorph structure with three proof mass). The piezoelectric, substrate and the proof mass materials are chosen to be PZT-5H, Structural steel and Aluminium. The simulation analysis for the eight types of structures are evaluated using COMSOL Multiphysics 5.3a and MATLAB software, in which the HBBBCGA optimized Type H structure generates maximum power respectively. An experimental study is conducted between the un-optimized and HBBBCGA optimized unimorph and bimorph structures (Type A, D, E and H) which are implemented using two case studies [(case study 1–25 years and 38 kgs) and (case study 2–40 years and 64 kgs)] in IoT based F-SEPS application. In the analysis, the case study 2 using HBBBCGA optimized Type H structure generates maximum amount of power and proved to be more effective for charging mobile devices.

In the microelectromechanical system, micropump is a very valuable device in various applications like drug delivery, electronics cooling system, etc. Control flow enhancement is the prime motive in the micropump application. In the case of diaphragm based micropump, fluid flow is based on the diaphragm actuation. The piezoelectric diaphragm is used for the control of fluid flow. In this paper new design of the piezoelectric actuator is proposed and compare with the regular circular actuator design and fluid flow analysis. Finite element analysis is carried out using ANSYS 12.1 software for the purpose. Simulation results show that the deflection of the new Strip Piezo Bimorph Disc (SPBD) actuator improves, thus improves the performance of the micropump.

Oscillation, widely existing in nature, is of vital importance for human society (e.g., energy utilization, signal transmission and communication), but preparing soft self-oscillators with facile accessibility, fatigue resistance, precise and noncontact control in multi-way tunable approaches is still desirable and challenging. Here, we report the fabrication of a light-driven tunable self-oscillator based on bimorph films of commercial Kapton and photoactive liquid-crystalline polymers with physical crosslinking sites, which can be remotely powered under constant irradiation of UV/visible light. The photomechanical behaviors of the bimorph actuators are acquired from the photoinduced changes in the volume of the photoactive polymer, and both the cis-azobenzene content and the trans–cis dynamic isomerization process are determinant factors. By combining the self-shadowing effect and inertia effect of the actuator, self-sustained oscillation is obtained. In nature, only leaves with particular size and weight could sway as appropriate strong wind blows from a specific direction, which inspires us to tune the oscillating frequency and amplitude with multiple approaches, like light intensity/wavelength (from UV to visible light), irradiated position, and size/weight of the oscillator for regulating the inertia effect. Such autonomously light-fueled self-oscillators are found to have potential applications in detecting charges and signal transmission.

This research paper is an attempt to present an insight into the use of micro electromechanical systems (MEMS) technology harvesting of green energy. One of the common examples of MEMS technology is by utilizing bimorph cantilever beams. Subsequently, it has also been discussed that Bimorph cantilever beam based sensors with high sensing ability could be used for harvesting energy from the physical environment. In this paper, we concentrate on the comparative analysis of the MEMS and piezoelectric materials which are used to design bimorph cantilever beams and convert mechanical energy into electrical energy. Detailed performance analysis of bimorph cantilever beams made of different materials has been carried out through various simulation models. Design and the simulation of bimorph cantilever beam is performed using Comsol multiphysics 5.2. state of art software. Comparative analysis of Lead zirconate (PZT-4D) and Lead zirconate (PZT-7A) has been done in this research to find more suitable material for fabrication of bimorph cantilever beams. PZT-7A is found to provide better electrical output for various analysis performed.

The optimization of the microactuation of shape memory alloy films in bimorph architectures was analysed for various film thickness and substrates material architectures, based on a known model that uses the fraction of phases during the martensitic transformation to evaluate the properties of the shape memory alloy film. It was shown by appropriately selecting the substrate material it is possible to maximize the deflection of the tip of a cantilever-type microactuator. For NiTi films, the increase of the active material thickness, as expected, leads to increased actuation, however the thermoeleastic properties of the substrate contribute to the stress achieved at the onset of the martensitic phase transformation, with higher values corresponding to larger actuation. Also depending on the thermoelastic constants of the substrate, the curvature of the cantilever-type microactuator can be toward the deposited film or toward the substrate. Si, Mo and Ti generated bending toward the shape memory alloy film, while Ni, stainless steel and Upilex S ended up bending toward the substrate. The result are important for the prediction of complex actuation complex architectures with potential to be used in micro-electromechanical systems.

Soft robots that can move like living organisms and adapt to their surroundings are currently in the limelight from fundamental studies to technological applications, due to their advances in material flexibility, human-friendly interaction, and biological adaptation that surpass conventional rigid machines. Light-fueled smart actuators based on responsive soft materials are considered to be one of the most promising candidates to promote the field of untethered soft robotics, thereby attracting considerable attention amongst materials scientists and microroboticists to investigate photomechanics, photoswitch, bioinspired design, and actuation realization. In this review, we discuss the recent state-of-the-art advances in light-driven bimorph soft actuators, with the focus on bilayer strategy, i.e., integration between photoactive and passive layers within a single material system. Bilayer structures can endow soft actuators with unprecedented features such as ultrasensitivity, programmability, superior compatibility, robustness, and sophistication in controllability. We begin with an explanation about the working principle of bimorph soft actuators and introduction of a synthesis pathway toward light-responsive materials for soft robotics. Then, photothermal and photochemical bimorph soft actuators are sequentially introduced, with an emphasis on the design strategy, actuation performance, underlying mechanism, and emerging applications. Finally, this review is concluded with a perspective on the existing challenges and future opportunities in this nascent research Frontier.

The article presents the study of the deformation of an SMA bimorph actuator during static heating. The thermomechanical behavior of thin film CuAlNiMn shape memory alloy (SMA) on polyimide substrate is analyzed using finite element method. The analysis is carried out for three different geometries to obtain the displacement when temperature is varied. The actuation characteristics of the SMA bimorph are studied through direct heating and joule heating techniques. The surface morphology and composition of the bimorph sample are obtained using the Scanning Electron Microscope (SEM). The numerical analysis of the thermomechanical behavior of a thin film CuAlNiMn SMA bimorph is carried out using the finite element method. The procedure is applied for a double-legged cantilever configuration of the bimorph to obtain the actuation in terms of displacement; by varying the temperature. The same is repeated for semi-circular and pentagon shapes of the bimorph to obtain the influence of area on the displacement. It is observed that SMA bimorph displaces with the rise in temperature and the magnitude of displacement increases with the increase in surface area of different geometries. The physical actuation characteristic of CuAlNiMn-polyamide bimorph is studied by thermal heating and electrical heating of the sample, which confirm the shape memory effect of the SMA and provide the displacement characteristics of the bimorph when applying an electrical current.

The article reviews the methods and instrumentation for the study of tribological and mechanical properties of the surface. It is established that the most common methods for studying these properties in the micro and nanodranges are contact methods based on the interaction of the hard tip with the material under study. In scanning probe microscopy for the complex study of tribological and mechanical properties of the surface, the main element of the measuring modules used for nanoindentation and sclerometry is a bimorph piezoceramic probe sensor with a diamond tip. The original design of the sensor allows to implement more than ten measuring techniques on one device. The operation of these devices in the semi-contact scanning probe-microscopic mode allows to obtain images of the surface relief and a map of the distribution of elastic properties. The indentation mode allows to measure hardness and modulus of elasticity, to estimate elastic recovery of material after indentation. The method of measuring hardness according to the image of the restored imprint (a method similar to classical microindentation) is implemented. The method of scratching is implemented, followed by obtaining image of the relief of the surface on the restored imprint. The method allows to determine the abrasion resistance and hardness of the material, adhesion and thickness of thin coatings.

In this paper, an active tactile sensor system for measurement of Young’s modulus and viscosity is developed. For the active sensing, the sensor unit with the 8 bimorph piezoelectric array is bonded to the speaker that is driven by a square wave. The transient response from the sensor signal of each bimorph piezo cell is processed to reduce the noise. From the output, the first peak and the ratio of first peak to time of first peak are extracted as the indexes for the measurement of Young’s modulus and viscosity, respectively. It is confirmed that the first peak has a clear correlation with the Young’s modulus, and that the ratio of first peak to time of first peak has a definite correlation with the viscosity. Further, the initial contact force affects the sensitivities of Young’s modulus and viscosity.

In this paper, the stress behaviour and power generation of cymbal bimorph transducer of different piezoelectric ceramics are studied. Comparison of stress, deformation and power is done between di...

Piezoelectric energy harvesting (PEH) provides an essential mode for the transformation of mechanical vibration to electrical form for providing continuous power to wireless sensor nodes in today’s...

A shape memory alloy (SMA) bimorph actuator is a composite structure composed of flexible polyimide substrate and SMA thin film deposited using thermal evaporation technique. In this work, the substrate thickness in the range of 25 - 75 mm was selected for the development of CuAlNiMn SMA bimorph actuator. An investigation on the control behavior of copper based SMA bimorph towards the development of micro positioning system has been performed. The actuation behavior of the SMA bimorph was studied using electrical actuation. Subsequently, a proportional integral derivative (PID) controller was designed to control the bimorph actuator with proper tuning of gain parameters. The displacement of the bimorph actuator was controlled through dedicated experimental setup consisted of laser displacement sensor, data acquisition system and LabVIEW software. The CuAlNiMn SMA bimorph actuator resulted in a satisfying control performance which can be extended to MEMS applications. A preliminary prototype of the SMA bimorph actuator based micro positioning system has been developed.

We propose reconfigurable metamaterials with multiband resonance in the terahertz (THz) frequency range. By modifying the pattern width and gap of metamaterial, these designs exhibit the characteristics of polarization-dependence, dual-band resonance, and triple-band resonance. Two cantilever metamaterial (CM) devices are demonstrated by using micro-electro-mechanical system (MEMS) based bimorph cantilevers array, which can be deflected toward the out-of-plane direction. The measured transmission spectra are greatly agreed well with the simulation results. By applying different direct current (DC) bias voltages, the bending degree and electromagnetic response of CM device could be controlled. The multiband resonance can be tuned in the range of 0.33 THz by applying a DC bias voltage of 30 volts. The relationship of the resonant shifts and the applied DC bias voltages is quite linear, which can assist the device to be more controllable and applied in more fields. Such designs are promising to be used in various applications, such as frequency-selective detectors, multispectra imagers, and multifunctional switches in the THz frequency range. [2020-0236]

Macro-Fiber Composite bimorph is a kind of piezoelectric actuator that allow large bending deformation. However, macro-fiber composites exhibit strong stiffness nonlinearity in their operation range, so it is difficult to accurately estimate their large deformation behavior based on a linear constitutive model. In addition, the macro-fiber composites have active and inactive parts, that significantly differ in their material sizes and properties, so it is not reasonable to consider them as uniform material. Thus, it is necessary develop an accurate modeling and analysis method for the large deformation macro-fiber composite structures. First, the mixing rules are extended to derive the three-dimensional homogenized mechanical and electrical parameters of the macro-fiber composite active part; based on these parameters, the actuation results of linear finite element model is in good agreement with the official data. Then a finite element model of the axially compressed macro-fiber composite bimorph is established, the bilinear tensile stiffness of macro-fiber composite is realized by secondary development in ANSYS. Comparison with the experimental results reveals high accuracy of the established finite element model. Thus, the developed method can be effectively used for the performance evaluation and design of the macro-fiber composite devices with large deformation.

A novel process was developed for the fabrication of 5–50 µm lead zirconate titanate (PZT) thick films on metal substrates. Tape cast PZT with a methyl cellulose binder was burned out at 275 °C, humidified, and then partially densified at 300 °C by cold sintering with a wet lead nitrate liquid phase. Lamination of the green tape on dense metal foils led to incomplete densification due to constrained sintering. However, when metal foils were replaced with tape cast Cu, fully sintered PZT/Cu/PZT composites were acquired after a secondary heat treatment at 800 °C. The PZT films has a relative permittivity over 500 and a loss tangent ~12% at 100 Hz because of a Cu2O interface between the PZT and Cu presumably formed during the cold sintering process. The polarization-electric field hysteresis loop shows a remanent polarization over 20 µC/cm2, and the e31,f of the samples is -4.7 C/m2.

This paper presents modification in the thickness profile of bimorph cantilever type piezoelectric vibration energy harvester (PVEH) to achieve uniform stress along the beam length. The thickness profile is obtained by varying the thickness of substrate layer and keeping the thickness of piezoelectric layers constant. Analytical expressions for the cantilever beam displacement, stress on the beam and generated voltage are derived and solved for sinusoidal input excitations. The results from the analytical expressions are validated with that of the finite element (FE) analysis of an identical PVEH. The generated power and stress distribution in the proposed PVEH are compared with that of an equivalent conventional PVEH of uniform thickness. Compared to the conventional PVEH, in the proposed PVEH the generated power is 20% higher for an input acceleration of 0.2g, and the stress on the proposed device is found to be uniformly distributed with the peak stress value reduced significantly by 46%.

This paper presents a non-polynomial coupled plate theory for smart composite structures employing inverse hyperbolic displacement and electric potential functions. The theory is utilized towards analysis of composite piezoelectric plates operating in sensor and actuator modes. Particularly, the following three cases are studied: (i) passive laminated composite structure, (ii) composite piezoelectric plate actuator and (iii) unimorph and bimorph piezoelectric plate sensors. Analytical solutions are obtained for simply supported plates under static electrical and mechanical loads. These results are validated with existing 3D elasticity solutions and compared with other plate theory solutions. Furthermore, parametric studies are performed to determine the effect of loading, span-to-thickness ratio and lamination sequence on the response of the piezoelectric plate. Finally, the theory is applied to a transverse shear sensing device which utilizes transverse shear-electric field coupling in piezoelectric materials. This effect is often ignored in literature. It is observed that the maximum percentage error of the present theory, when compared with 3D results, is less than 3%, which is lower than other higher order plate theories.

In this article, proposed is a hysteresis effects model of a bimorph circular flexural-mode piezoelectric actuator for a deformable mirror of adaptive optics system. The analytical solutions are derived from the three-dimensional equations of piezoelectricity, and the dependence of the nonlinear hysteresis performance of the actuator on the physical parameters is evaluated. Numerical results illustrate that the hysteresis loops of the strokes of the actuator are affected by the start values of the electric field and the thickness of the metallic layer. Besides, the results also suggest that an appropriate thickness of metallic layer could compensate some hysteresis effects. Moreover, the results of the analytical method have been demonstrated by those of the finite element method.

A nonlinear micro-piezoelectric–electrostatic energy harvester is designed and studied using mathematical and computational methods. The system consists of a cantilever beam substrate, a bimorph piezoelectric transducer, a pair of tuning parallel-plate capacitors, and a tip–mass. The governing nonlinear mathematical model of the electro-mechanical system including nonlinear material and quadratic air-damping is derived for the series connection of the piezoelectric layers. The static and modal frequency curves are computed to optimize the operating point, and a parametric study is performed using numerical methods. A bias DC voltage is used to adapt the system to resonate with respect to the frequency of external vibration. Furthermore, to improve the bandwidth and performance of the harvester (and achieve a high level of harvested power without sacrificing the bandwidth), a nonlinear feedback loop is integrated into the design.

Piezoelectric energy conversion has received considerable attention for vibration-to-electric energy conversion over the past decade. A typical piezoelectric energy harvester is a unimorph or a bimorph cantilever located on a vibrating host structure. This paper presents a comparison between unimorph and bimorph cantilever beam having a number of segmented PMN-PT piezo-elements on the input and output power. The numerical simulation was carried out by applying the finite element analysis (FEA) using COMSOL multi-physics software in order to predict output voltage and power over a frequency range of 60–200 Hz for the first resonant frequencies. The simulation results show maximum output voltage and power harvested of 7.38 V and 135.73 μW, respectively, by the unimorph piezoelectric energy harvester at resonant frequency value of 84 Hz with electromechanical coupling factor (ke) of 77.29%. These results highlight that the highest value of the output electrical power can be obtained when the piezoelectric element is attached on the top of a clamped end of a cantilever piezoelectric beam. Moreover, in an unimorph or bimorph cantilever beam system, increasing the number of piezoelectric elements results in a higher resonant frequency shift and significantly decreasing in the harvested power.

The challenge of continuously powering the wireless sensor network located at remote areas has been resolved by the emergence of piezoelectric energy harvester. This paper evolved a new idea of using different piezoelectric materials together within segmented doubly clamped bimorph piezoelectric energy harvester (DCBPEH). The finite element modeling of the device has been presented here using COMSOL multiphysics software. This paper starts with concept of strain nodes and further better performance of segmented electrodes-based beam over the continuous electrode-based beam has been achieved. Next, a performance analysis study with continuous electrode-based beam has been carried out for different variants of two piezoelectric materials, namely, PMN-xPT and PZT. From this study, PMN-35%PT and PZT-5H piezoelectric materials are found to be best variants. Finally, the performance of segmented DCBPEH has been observed for different positioning formats of PMN-35%PT (M1) and PZT-5H (M2) piezoelectric materials on different segments of the beam. From this analysis, M1–M1–M2 and M2–M1–M1 are noted to be two favorable positioning formats which provide similar and maximum performance (7.78 mW) as compared to other formats.

In order to investigate the mechanical properties of Ag-IPMC artificial muscles, establishing the mathematical model of Ag-IPMC under non-electrically actuated conditions by superelastic large deformation equation. The mechanical simulation and experimental comparison of Ag-IPMC with different moisture contents were carried out. The piezoelectric coefficient from the bimorph piezoelectric model was equivalently analogized to the calculating of the Ag-IPMC model so that the model was more suitable for the characteristics of nonlinear large deformation of Ag-IPMC. According to the data from the analysis, a conclusion can be drawn: when the moisture content of Ag-IPMC was within a certain range, with the decrease of moisture content of Ag-IPMC, the strain was small under low voltage or low moisture content conditions. Meanwhile, the smaller the strain, the smaller the extrusion of the root where the place was clamped causing by the Ag-IPMC deformation. The mechanical properties of Ag-IPMC were the coupling result of comprehensive factors. Simply improving the performance of any single item would affect the overall mechanical properties.

Piezoelectric bimorphs have a promising application in morphing micro air vehicles; however, increasing the actuation displacement is a difficult point. Axial compression can be used to increase the deformation of the piezoelectric bimorph. Compared with piezoelectric ceramics, macro fiber composites offer higher flexibility. In this article, a large displacement actuator of axial-compressed macro fiber composite bimorph is proposed. A multi-layer parallel scheme of macro fiber composite bimorphs is presented to increase the output torque of piezoelectric bimorph within a limited space. The actuation performance of the axial-compressed macro fiber composite bimorph and its multi-layer parallel scheme are verified through quasi-static experiment and displacement tracking control test. The experimental results show that the end-free rotations of both the axial-compressed macro fiber composite bimorph and its multi-layer scheme achieve ±8.1°, which is 60% higher than that of a piezoelectric ceramics bimorph with the same length. The blocking torque of the single-layer macro fiber composite bimorph is 0.028 Nm. The proposed parallel bimorphs method can magnify output torques. In addition, the axial-compressed macro fiber composite bimorph can accurately track any displacement signals in the range of its actuation. It is a continuous and controllable piezoelectric bimorph with large displacement.

A printed flexible hybrid electronics (FHE) technology platform is described, which combines a thin-film audio speaker, printed interconnects, and printed passive components in a highly flexible system. Bimorph piezoelectric polymer speaker structures were developed and shown to give increased loudness compared with a single layer speaker, with good fidelity and easily recognizable sound. Speakers were fabricated on flexible thin polyimide substrates, which enables integration with printed electronics and other thin-film devices. Two demonstrator circuits were designed to operate the speakers and were fabricated using printed FHE techniques. One circuit was an amplifier for a portable music player, and the second provides a record and playback function using an audio integrated circuit. The fabrication of these devices included ink-jet printed interconnects and ink-jet printed resistors, which showed a good long-term stability and flexibility.

This paper reports two piezoelectric materials of lead zirconium titanate (PZT) and aluminum nitride (AlN) used to simulate microelectromechanical system (MEMS) speakers, which inevitably suffered deflections as induced via the stress gradient during the fabrication processes. The main issue is the vibrated deflection from the diaphragm that influences the sound pressure level (SPL) of MEMS speakers. To comprehend the correlation between the geometry of the diaphragm and vibration deflection in cantilevers with the same condition of activated voltage and frequency, we compared four types of geometries of cantilevers including square, hexagon, octagon, and decagon in triangular membranes with unimorphic and bimorphic composition by utilizing finite element method (FEM) for physical and structural analyses. The size of different geometric speakers did not exceed 10.39 mm2; the simulation results reveal that under the same condition of activated voltage, the associated acoustic performance, such as SPL for AlN, is in good comparison with the simulation results of the published literature. These FEM simulation results of different types of cantilever geometries provide a methodology design toward practical applications of piezoelectric MEMS speakers in the acoustic performance of stress gradient-induced deflection in triangular bimorphic membranes.

Photothermal bimorph actuators have attracted considerable attention in intelligent devices because of their cordless control and lightweight and easy preparation. However, current photothermal bimorph actuators are mostly based on films or papers driven by near-infrared sources, which are deficient in flexibility and adaptability, restricting their potential in wearable applications. Herein, a bimorph textile actuator that can be scalably fabricated with a traditional textile route and autonomously triggered by sunlight is reported. The active layer and passive layer of the bimorph are constructed by polypropylene tape and a MXene-modified polyamide filament. Because of the opposite thermal expansion and MXene-enhanced photothermal efficiency (>260%) of the bimorph, the textile actuator presents effective deformation (1.38 cm–1) under low sunlight power (100 mW/cm2). This work provides a new pathway for wearable sunlight-triggered actuators and finds attractive applications for smart textiles.

In this work, the optimal design of an unmanned aerial vehicle (UAV) wing spar by multi-objective optimization genetic algorithms is studied. An electromechanical finite element model (FEM) for piezolaminated bimorph cantilever structure with embedded piezoceramics is used combined with multiobjective genetic algorithms. The FEM formulation is based on laminated plate theory combined with the first-order shear deformation theory (FSDT) for which each piezoelectric layer has one additional electrical degree of freedom. Non-dominated Sorting Genetic Algorithm II (NSGA-II), Non-dominated Sorting Genetic Algorithm III (NSGA-III) and Generalized Differential Evolution 3 (GDE3) algorithm have been used to optimize the geometric and electric circuit parameters of a UAV generator for maximum power output and minimum mass added by the embedded piezoceramics. It is shown that the proposed algorithms are effective in developing optimal Pareto front curves for maximum electrical power output of the generator spar and minimum mass add by the embedded piezoceramics. Comparison of the generated solutions on the Pareto Front for UAV wing spar design shows that all three algorithms achieve solutions that closely resemble a constructed reference Pareto optimal front.

Silicon is regarded as one of the most promising anode materials for lithium-ion batteries. Its high theoretical capacity (4000 mAh/g) has the potential to meet the demands of high-energy density applications, such as electric air and ground vehicles. The volume expansion of Si during lithiation is over 300%, indicating its promise as a large strain electrochemical actuator. A Si-anode battery is multifunctional, storing electrical energy and actuating through volume change by lithium-ion insertion. To utilize the property of large volume expansion, we design, fabricate, and test two types of Si anode cantilevers with bi-directional actuation: (a) bimorph actuator and (b) insulated double unimorph actuator. A transparent battery chamber is fabricated, provided with NCM cathodes, and filled with electrolyte. The relationship between state of charge and electrode deformation is measured using current integration and high-resolution photogrammetry, respectively. The electrochemical performance, including voltage versus capacity and Coulombic efficiency versus cycle number, is measured for several charge/discharge cycles. Both configurations exhibit deflections in two directions and can store energy. In case (a), the largest deflection is roughly 35% of the cantilever length. Twisting and unexpected bending deflections are observed in this case, possibly due to back-side lithiation, non-uniform coating thickness, and uneven lithium distribution. In case (b), the single silicon active coating layer can deflect 12 passive layers.

In this paper, an acoustic resonator with frequency > 5 GHz is designed, implemented, and measured with electromechanical coupling exceeding 15% and low temperature dependence compared to conventional Lamb-wave resonators. The acoustic resonator is optimized for the S4 mode Lamb waves in a bi-morph composed of Lithium Niobate and Silicon Dioxide. The resonator optimization is based on adjusting the thickness of different materials in the bimorph to maximize the coupling and minimize temperature dependence simultaneously. The achieved specifications are adequate for 5G sub-6 GHz frequency band n46 in addition to Wi-Fi new bands between 5 and 6 GHz.

In this investigation the modeling and analysis of dynamic structured Macro-Fiber Composite (MFC) for ambient power has been composed to unimorph and bimorph cantilever beam. The dimensions of the beam and its properties were investigated in order to tip displacement across its length with active and inactive piezoelectric layers of MFC. To optimize structure of a cantilever beam with respect to natural frequency, more effective vibration control that can be achieved with minimum control input. The results show that the dynamic model of the cantilever beam is validated with comparisons of experimental, theoretical data and analytical investigation by using ANSYS Simulation.

This paper presents the investigation of a crack repair in a composite plate using piezoelectric smart material, which is also called as active repair. Composite plate with crack is modeled by a finite element method. An 8-node structural shell element is used to discretize composite material, and the 8-node coupled-field element is used for the modeling of the piezoelectric patch. The repair in the cracked composite plate is modeled and analyzed under both static and dynamic loading conditions. The unimorph and bimorph patching are used for active repair. Effectiveness of the patch repair is measured in terms of stress field near the crack tip. The usefulness of unimorph and bimorph patching is compared in three different cases, namely (i) passive, (ii) active and (iii) without patching. A significant reduction in the equivalent stress at the crack tip of the composite plate is observed because of repair by unimorph and bimorph active patching. Bimorph patching presents a greater reduction in the stress level near to discontinuity

To meet the dual requirement of high flow rate and high output pressure in water-cooling system of electronic chip, a quintuple-bimorph tenfold-chamber piezoelectric pump (QTPP) is presented, which owns the comprehensive advantages of parallel and serial connection. QTPP is composed of two groups of five-chamber-in-series, and the two groups of five-chamber-in-series can be in parallel or serial. QTPP is designed and fabricated, the output performance of which is invested by experiments. The experimental results show that QTPP can obtain high flow rate and high output pressure under low driving voltage. When driven by quintuple piezoelectric vibrators under 60Vpp, QTPP in parallel can obtain the maximum flow rate of 251.1ml/min and the maximum output pressure of 60.2kPa. While in serial, QTPP can obtain 186.2ml/min and 109.9kPa respectively. The water-cooling system with QTPP is established and experimented. The experimental results indicate that the water-cooling system with QTPP can achieve a good cooling performance under low driving voltage. Under the driving voltage of 60Vpp, QTPP can reduce the temperature of stimulate chip from 107.8°C to 51°C.