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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.

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.

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.

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.

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.

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...

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]

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.

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.

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.

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.

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.

The problem of constructing a thermal sensor based on the technology of microelectromechanical systems is solved by structural and circuit integration of capacitance-dependent and thermomechanical parts. For this, the use of a MOS transistor (capacitance-dependent part) with a gate in the form of a bimorph membrane (thermomechanical part), which performs cyclic oscillations under the influence of heating from a sensitive element and subsequent cooling, is proposed. The novelty of the proposed sensor is the provision of a frequency-dependent output signal without the use of additional generator circuits. This makes it easier to combine the sensor with digital signal processing systems and reduce the influence of transmission lines on measurement accuracy. Also, the advantages of the sensor include reduced overall dimensions, which is achieved due tothevertical integration of its elements. Model studies of the sensor are carried out and on their basis circuit and software-hardware solutions for determining the temperature of the sensitive element are proposed. It is shown that the use of logarithmic dependence to approximate the influence of the temperature of the sensitive element on the output pulse frequency of the sensor minimizes the measurement error to 3.08%. The composition of the information and measurement system, which contains a thermal sensor, a sensor signal pre-processing circuit and measurement processing unit using the Atmega328 microcontroller on the platform of the unified ArduinoUno module, is determined. It is shown that the total error of temperature determination in the developed system does not exceed 4.18% in the temperature range of the sensor element from 20 °C to 47 °C. The program code for the microcontroller part of the information and measurement system is developed, which occupies 12% of the program memory and 4.9% of the dynamic memory of the unified module. The proposed thermal microelectromechanical sensor can be used for contact measurement ofthetemperature of gaseous and liquid media, recording of optical radiation and microwave signals

The development of wearable devices and remote sensor networks progressively relies on their increased power autonomy, which can be further expanded by replacing conventional power sources, characterized by limited lifetimes, with energy harvesting systems. Due to its pervasiveness, kinetic energy is considered as one of the most promising energy forms, especially when combined with the simple and scalable piezoelectric approach. The integration of piezoelectric energy harvesters, generally in the form of bimorph cantilevers, with wearable and remote sensors, highlighted a drawback of such a configuration, i.e., their narrow operating bandwidth. In order to overcome this disadvantage while maximizing power outputs, optimized cantilever geometries, developed using the design of experiments approach, are analysed and combined in this work with frequency up-conversion excitation that allows converting random kinetic ambient motion into a periodical excitation of the harvester. The developed optimised designs, all with the same harvesters’ footprint area of 23 × 15 mm, are thoroughly analysed via coupled harmonic and transient numerical analyses, along with the mostly neglected strength analyses. The models are validated experimentally via innovative experimental setups. The thus-proposed ϕ = 50 mm watch-like prototype allows, by using a rotating flywheel, the collection of low-frequency (ca. 1 to 3 Hz) human kinetic energy, and the periodic excitation of the optimized harvesters that, oscillating at their eigenfrequencies (~325 to ~930 Hz), display specific power outputs improved by up to 5.5 times, when compared to a conventional rectangular form, with maximal power outputs of up to &gt, 130 mW and average power outputs of up to &gt, 3 mW. These power levels should amply satisfy the requirements of factual wearable medical systems, while providing also an adaptability to accommodate several diverse sensors. All of this creates the preconditions for the development of novel autonomous wearable devices aimed not only at sensor networks for remote patient monitoring and telemedicine, but, potentially, also for IoT and structural health monitoring.

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 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.

Bimorph deformable mirrors can be successively used to improve focusing of a laser beam passed through a moderately scattering medium with optical density in the range of 1 ... 10. In this paper we investigate the efficiency of the stacked actuator deformable mirror with 61 piezo stacks and clear aperture of 60 mm. We demonstrate that such kind of mirrors also can be used to optimize the focal spot in the far-field. Shack-Hartmann sensor was used to measure the averaged wavefront distortions and CCD camera was used to estimate the intensity distribution of the focal spot in the far-field.

PZT (lead zirconate titanate)-glued bimorph deformable mirrors are widely used in hard x-ray regimes[1], however, they have not yet been used in soft X-ray regimes because they are less compatible for usage under high vacuum. Therefore, we have developed a glue-free bimorph deformable mirror, in which silver nanoparticles were employed to bond PZT actuators to mirror substrates[2]. In this study, we achieved a 2 nm figure error on an elliptical shape of a glue-free deformable mirror. We evaluated the figure change characteristics due to humidity and temperature increasing at the ultrafine figure error condition.

This contribution describes the feasibility of a wireless sensor that uses Micro-Electro-Mechanical Systems (MEMS) on cellulose materials. In particular, the focus is on a paper-aluminum (paper-Al) bimorph cantilever formed by an Al foil glued on top of a paper layer. It is well known that paper relaxes its fibers in the presence of humidity. This means that the length of the paper layer increases (respect to the Al layer) when humidity is absorbed, thus determining the cantilever deflection. Such a mechanism is used to control a capacitor formed by the cantilever itself (Al layer) and by a metal plate printed on a PCB. The capacitor is then applied to a planar notch filter whose resonant frequency is hence determined by the humidity. The preliminary experiments show that the developed circuit features a 2.45 GHz center frequency and a sensitivity of about 3.7 MHz ner each nercent of relative humidity variation.

In this paper, the design, implementation, and measurements of a near-zero temperature coefficient of frequency (TCF) acoustic resonator are demonstrated. The acoustic resonator is based on laterally vibrating Lamb-waves in a bimorph composed of Lithium Niobate and Silicon Dioxide. The resonator is optimized for the A3 mode by adjusting the thickness of different materials in the bimorph to maximize the coupling and minimize the TCF simultaneously. The optimization resulted in ultra-low TCF of −1.1 ppm/°C, a high electromechanical coupling of 13.5%, and a good quality factor of 500 at 3.5 GHz. The achieved specifications are adequate for 5G sub-6 GHz frequency bands n77 and n78.

Deformable mirrors in adaptive system for high power lasers should have high damage threshold and thermally stabilized surface. The cooling is required for average beam power above 100W. In this paper, the problem of the thermo-stabilizing of the deformable mirrors is studied. Bimorph deformable mirrors (BDM) and stack actuator deformable mirrors (SADM) are considered. For BDMs the active and passive cooling designs have been implemented. In active design, the waffletype cooling system for circulation of the cooling liquid was made inside of the thin substrate. In passive design, the periphery surface is thermally contacted with the condenser which temperature is constant. Such BDMs not damaged at CW power density 20kW/cm2 when the beam fills full surface of the mirror and can be used in powerful solid state ceramic YAG lasers. SADM is most suitable to correct for small-scale and high-speed aberrations. We developed SADM where reflecting substrate is cooled through the actuator bodies. Individual actuators are housed in metal holders and can be replaced if they fail due to electrical breakdown. SADM has the diameter 120 mm and included 121 actuators. The deformation stroke of the actuator was 7μ. The first resonant frequency was 18.5 kHz, which allowed operating in adaptive system in kHz range.

The ubiquity of vibration sensors and accelerometers, as well as advances in microfabrication technologies, have led to the development of implantable devices for biomedical applications. This work describes a piezoelectric microelectromechanical systems accelerometer designed for potential use in auditory prostheses. The design includes an aluminum nitride bimorph beam with a silicon proof mass. Analytic models of the device sensitivity and noise are presented. These lead to a minimum detectable acceleration cost function for the sensor that can be used to optimize sensor designs more effectively than typical sensitivity maximizing or electrical noise minimizing approaches. A fabricated device with a $1~\mu \text{m}$ thick, $100~\mu \text{m}$ long, and $700~\mu \text{m}$ wide beam and a $400~\mu \text{m}$ thick, $63~\mu \text{m}$ long, and $740~\mu \text{m}$ wide proof mass is tested experimentally. Results indicate accurate modeling of the system sensitivity up to the first resonant frequency (1420 Hz). The low-frequency sensitivity of the device is 1.3 mV/g, and the input referred noise is 36.3 nV/ $\sqrt {\mathrm{Hz}}$ at 100 Hz and 11.8 nV/ $\sqrt {\mathrm{Hz}}$ at 1 kHz. The resulting minimum detectable acceleration at 100 Hz and 1 kHz is $28~\mu \text{g}/\sqrt {\mathrm{Hz}}$ and $9.1~\mu \text{g}/\sqrt {\mathrm{Hz}}$ , respectively. A brief explanation of the use of the validated cost function for sensor design is provided, as well as an example comparing the piezoelectric sensor design to another from the literature. It is concluded that a traditional single-resonance design cannot compete with the performance of acoustic sensors; therefore, novel device designs must be considered for implantable auditory prosthesis applications.

Low-frequency vibration energy harvesting is becoming increasingly important for environmentally friendly and biomedical applications in order to power various wearable and implanted devices. In this paper, we propose the use of piezoelectric congruent LiNbO3 (LN) single crystals, with an engineered bidomain structure, as an alternative to the widely employed lead-based PZT. We thus compared experimentally the pure vibration energy scavenging performance of square-shaped bidomain and single-domain Y+128°-cut LN crystals and a conventional bimorph soft PZT ceramic bonded to long spring-steel cantilevers as a function of the frequency, load resistance, and tip proof mass. At a low bending resonance frequency of ca. 32.2 Hz, the bidomain LN yielded an open-circuit voltage of 1.54 kV/g, almost one order of magnitude larger than that observed in PZT. The maximum extractable average power was found to be of 9.2 mW/g2 in the bidomain LN, 6.2 mW/g2 in the single-domain LN, and 1.8 mW/g2 in the PZT piezo-elastic cantilevers. With five times higher output power density of up to 11.0 mW/(cm $^{3}\cdot \text {g}^{2}$ ) under resonance conditions, bidomain LN was thus shown to be a reliable lead-free and high-temperature alternative to PZT, thanks to its considerably larger quality factor and electromechanical conversion efficiency.

This paper presents the new design and fabricating process of a packaged micro piezoelectric vibration energy harvester (PVEH). Structures are designed and parameters are optimized through finite element modelling and analysis. The double L-shaped tungsten proof mass block and thick copper-based PZT bimorph are proposed to ensure the harvester with high electrical power. Polymethyl methacrylate (PMMA) packaging and epoxy resin bonding supply the flexible clamping of piezoelectric cantilever, which decreases the resonant frequency, increase average PZT stress, reduces the maximum PZT stress and broadens the effective frequency range. Bulk PZT bonding is used in PVEH prototype fabrication. Experimental results show that the packaged PVEH resonates under the excitation of 1 g (9.8 m s−2) at 160 Hz. It has an optimum resistance load of 47 kΩ. More importantly, its maximum output power is 2.49 mW in experiments, and the half-power bandwidth is 22 Hz. After package, it has a high volume power density of 0.64 mW/cm3 g2 with the volume of 3.9 cm3 (2 cm × 1.5 cm × 1.3 cm). Connected with energy harvesting circuit, PVEH can light up a light emitting diode (LED) under broadband vibration frequency. The proposed PVEH with broadband output power in mW level is promised to power up some microelectronic devices for application.

This paper presents a high-performance bimorph MEMS cantilever harvester with partially covered asymmetrical functional piezoelectric layers on both sides of a beryllium bronze foil. The optimal PZT coverage length is employed to improve the output power density. The two piezoelectric layers with the controlled different thicknesses for the top and bottom PZT layers can provide three different output powers. Furthermore, a proof mass tungsten bonded at the free end of the cantilever can reduce the resonant frequency. The experimental results showed that the serial-connected bimorph piezoelectric energy harvester can obtain the maximum power density of 26.90 mW/cm3 at the matched loading resistance of 660 $\text{k}\Omega $ under 1.5-g acceleration at the resonant frequency of 38.89 Hz. The normalized power density of the harvester can reach $307.4\,\,\mu \text{W}\cdot \text{g}^{-2}\,\,\cdot $ cm $^{-3}$ . Meanwhile, the harvester provides good stability under 1.5-g acceleration amplitude.

Multi-responsive actuators have recently aroused intensive research for the requirements of being used in various environments. However, their actuation performances are generally lower than their single responsive counterparts because of the restriction of material selection and complicated structural design. Here, for the first time, a multi-responsive actuator that can respond to four types of stimuli including electricity, near infrared light, humidity, and organic vapors was designed by attaching superaligned carbon nanotubes sheets and coating an ink layer on the both sides of the PET film. The multi-responsive actuator shows fast and reversible actuation with high displacement-to-length ratio of 0.79 under electrical stimulus, and large bending angle of 212ο in 0.55 s at a bending speed of 646ο/s under near infrared light irradiation. The actuator also shows fast response exposing to moisture and volatile organic vapors. The actuator shows a large bending angle within ∼0.1 s when exposed to different organic solvents and recovered its initial shape when the solvent was removed. These performances are in the same level of the record values of the thermal-based bimorph actuators. We demonstrated this actuator as a smart electric-control frequency switch at relatively high on/off frequency up to 17.5 Hz.

A resonant operation mode of a new adaptive bending X-Ray optics (ABXO) element based on bidomain LiNbO3 single crystal piezoactuator is studied and described. Spatial and temporal parameters of X-Ray beam tuning by this element are investigated. Experimental measurements and numerical calculations have been performed for the element functional characteristics: oscillatory spectrum, speed of angular adjustment, angular range of scanning. For the first time, the application of the ABXO element has been tested at a source of synchrotron radiation for controlling the X-Ray beam parameters in time-resolved X-Ray diffraction experiments.

Functional characteristics of a new adaptive bending X-Ray optics (ABXO) element for fast X-Ray beam parameters control are investigated and described. The element operates on a bending oscillation principle and consists of LiNbO3-based bimorph piezoactuator and a silicon single crystal of high quality mounted on its edge. Static and quasistatic operation modes of this ABXO element are described. Features of the X-Ray beam angular shift at different amplitudes, frequencies and waveforms of the control electric signal have been investigated using diffractometry with a millisecond time resolution. А high positioning accuracy of the ABXO element at low frequencies (up to the first resonant harmonic) is demonstrated. Estimations of the tuning time have been made, which was several tens of milliseconds.

We assess the accuracy of plane state assumptions in modeling the bending of bimorph piezoelectric cantilevers. Reference solutions are obtained by means of fully three-dimensional simulations. We solve a model, compliant with the standard theoretical background, able to deal with large deflections, and aimed at estimating the electrical energy harvesting potential. We show that the two assumptions of plane stress and plane strain yield very different results in terms of strain and therefore lead to substantially different estimates of electrical power. The plane stress state is the best approximation of narrow cantilevers, while the plane strain is suited for wide ones. The validity ranges are defined for each of the two, in terms of the generated electrical power. More specifically, the plane stress assumption better approximates the reference solution in the range [Formula: see text]. By contrast, the plane strain condition yields results closer to three-dimensional solution for ratios [Formula: see text] with W the width and H the total thickness of the solid. Other aspects are affected by the modeling approach, such as the estimation of maximum deformation and, to a minor extent, of resonance frequencies.

The results of experimental and theoretical studies of femtosecond laser pulse filamentation with use of a bimorph deformable mirror are presented. The mirror allows controlling the position of the filamentation domain throughout a model path due to phase distortions of different parts of a laser beam, determining localization of filaments and high-intensity channels in a beam cross section, and forming long (>100 m) high-intensity (1011–1012 W/cm2) weakly diverging plasma-free channels.

To develop highly efficient energy harvesting means to sustainably driving miniaturized portable electronic devices, the hybrid nanogenerators (NGs) are emerging to compensate for the respective shortcomings of either type of NG. However, the crucial factors affecting the output performances of hybrid NGs still exist, such as the driving frequency, phase difference and mismatched impedance. Here, the bimorph-based piezoelectric NG was integrated into the triboelectric NG to construct a hybrid piezo/triboelectric NG (H-P/TENG) for highly efficient mechanical rotation-energy harvesting. Systematic measurements and analyses illustrated the output performance of H-P/TENG was independent of the rotation speed (driving frequency) due to the invariable periodic deformation degree of the H-P/TENG. Both NGs in the H-P/TENG had the identical phase and matched impedance in the same magnitude, which were beneficial for direct coupling of their individual rectified output signals and avoided unnecessary energy loss from the utilization of transformer. Under a low rotation speed of 100 rpm, the proposed H-P/TENG delivered high output voltage, output current and large average power/power density at ~210 V, 395 μA and 10.88 mW/6.04 mW cm−2, respectively. The output voltage/current of the sophisticated H-P/TENG could retain at ~210 V/400 μA under rotation speeds from 50 to 250 rpm. Through integrating an energy managing circuit with the H-P/TENG, we developed a DC power source (stable DC output at 3.6 V) to sustainably drive RF wireless temperature sensing network and commercial electronics. The H-P/TENG was also capable of producing high output voltage (150 V) and current (150 μA) at wind speed of 14 m/s to power 50 LEDs in parallel connection. The distinctive structure and outstanding performance of this hybrid NG is promising for the practical application of self-powered systems and the large-scale energy conversion.

A cloth that adapts to the heat Textiles trap infrared radiation, which helps keep us warm in cold weather. Of course, in hot weather, this is less desirable. Zhang et al. constructed an infrared-adaptive textile composed of polymer fibers coated with carbon nanotubes. The yarn itself expanded and collapsed based on heat and humidity, which changed the spacing of the fibers. Wider fiber spacing allowed the textile to breathe but also altered the infrared emissivity of the textile. This allowed for better heat exchange under hot and wet conditions. The self-adjusting emissivity of the textile could help toward wearable thermal-management attire. Science , this issue p. 619

Microelectromechanical systems (MEMS) are micrometre-size systems that are capable of transforming electrical signals to mechanical signals. In this paper, the use of MEMS devices as a method for harvesting waste heat is explored. A background for the technology and methods is discussed and a method proposed for a working device based upon a thermally heated bimorph actuated by waste radiation alone is investigated. A chopper interrupts the radiant energy inducing an oscillation in the bimorph temperature and thus creates a mechanical motion which can be taken advantage of using piezoelectric materials. Difficulties in harvesting radiant energy with this method are highlighted and suggestions for non-passive energy generation are made based on the outlined principles.

The time-domain bending behaviour of piezoelectric bimorph deformable X-ray mirrors for use at synchrotron and X-ray free-electron laser sources is investigated for the first time using high-speed Fizeau interferometry. It is demonstrated that several hardware and software innovations enable the optical surface of such mirrors to be rapidly tuned and stabilized on the nanometre scale within only a few seconds., Piezoelectric bimorph deformable mirrors (‘bimorphs’) are routinely used on many synchrotron and free-electron laser beamlines to provide active variation in the size and shape of the X-ray beam. However, the time-domain potential of such optics has never been fully exploited. For the first time, the fast dynamic bending response of bimorphs is investigated here using Fizeau interferometry. Automated scripts for acquisition and analysis were developed to collect Fizeau data at a rate of 0.1 Hz to record dynamic changes in the optical surface as voltages were applied to the electrodes of the piezoelectric actuators. It is demonstrated that residual drift in the tangential radius of curvature of a bimorph can be significantly reduced using enhanced opto-mechanical holders and a fast programmable high-voltage power supply. Further improvements are achieved by applying small opposing voltages to compensate for piezoelectric creep. The present study shows that bimorphs can truly be used as high-speed adaptive optics for the X-ray domain, even without closed-loop feedback correction. This opens the possibility for relatively simple real-time tuning of the profile of X-ray bimorphs. Part II of this study [Alcock, Nistea, Signorato, Owen, Axford, Sutter, Foster & Sawhney (2019), J. Synchrotron Rad. 26, 45–51] builds upon these results and demonstrates how bimorphs can rapidly provide customisable sizes and shapes of synchrotron X-ray beams, specifically tailored to suit the experimental samples being investigated.

In order to collect energy from human activities, piezoelectric energy harvesters should have a flexible structure, low resonant frequency and wide frequency bandwidth. In this paper, the fabrication and characterization of a metal-based Pb(Zr,Ti)O3 (PZT) bimorph thick film energy harvester. PZT thick films were deposited on cantilever-shaped titanium (Ti) substrate via a dip-coating process. The electrical properties of the PZT films sintered at different temperatures were investigated. The nonlinear piezoelectric energy harvester has the following advantages: it is suitable for low frequency, weak vibration, and wide frequency bandwidth. The maximum open-circuit voltage of the piezoelectric energy harvester is 1.6 V and the output power is 0.85 μW with 150 kΩ load resistance at low resonant frequency of 17.6 Hz when the input vibration acceleration was 0.12 g. In addition, the frequency bandwidth is broadened from 0 to 8.4 Hz as the input acceleration increases from 0.05 g to 0.12 g. Keywords: Energy harvesting, PZT, Sintering temperature, Nonlinear vibration

The results of experiments conducted on a laboratory setup of a fast adaptive optical system based on the use of FPGA as the main control element and a bimorph mirror as a wavefront corrector are presented. The adaptive system bandwidth ranged from a dozen Hertz to 2,000 Hertz. For independent control of the quality of correction the intensity distribution in the far field was recorded. It is shown that for a good correction of the wavefront the system bandwidth should be an order of magnitude higher than the upper boundary of the spectrum of wavefront distortions caused by turbulence. A comparison of the model and experimental data is also presented.

Adaptive system for wavefront correction based on 240-mm bimorph deformable mirror and Shack-Hartmann wavefront sensor is presented. The dynamic characteristics of the deformable mirror and the performance of the wavefront correction in various operating modes of the PEARL facility as well as the features of phase distortion compensation in a single-shot generation regime are studied. An improvement in the quality of focusing that led to an increase in the Strehl ratio to 0.6 is demonstrated.

In this paper, a new design of an electrothermal micromirror integrated with piezoresistive sensors is proposed. The micromirror is composed of four electrothermal bimorph actuators and four piezoresistive position sensors. In order to reduce the influence of temperature on piezoresistance, silicon dioxide can be used to thermally isolate the piezoresistive sensors from the silicon substrate. The optimized micromirror has a square mirror plate of 1800 * 1800 μm2 and a footprint of 4040 * 4040 μm2 , leading to a fill factor of 20%. The simulation results show that the optical fields of view of the micromirror are about 7° in the tilt and tip directions and the maximum piston displacement is close to 600 μm. The simulation results also show that the sensitivity and resolution of the piezoresistive sensors under a 3 V bias voltage are 2.88 mV/° and 0.4 μrad for the tip-tilt motion, respectively, and 0.056 mV/μm and 1.2 nm for the piston motion, respectively.

There is experimental need for devices that provide a series of independent dot-stimulation on human skin to simulate tactile perception in order to investigate human somatosensory system, such as somatotopic map. This actuation device requires precise mechanical design to achieve the required mechanical vibration specification and magnetic-field compatibility. After comparing the device structure published in previous studies, we introduce a single-dot-stimulation module including the mechanical structure and control system, which can generate reciprocating motion actuated by bimorph based on the inverse piezoelectric effect. The modules have the potential to be assembled together quickly according to the number of channels required by the tactile stimulation device. To verify the feasibility of the design, we also produced a prototype to test the output characteristics of the module. The results show that the designed module could actuate a carbon fibre rigid string with 0.5mm diameter and 1m long and generate stable 2.6mm displacement output from 0-20 Hz under 200V driving voltage. Finally, we conclude the structure of the single-dot-stimulation module and propose the improvement ideas.

The development of an untethered soft actuator that can perform complex task under external control is highly desirable. In this work, we present an ultrasonically actuated programmable polymorphic soft actuator scheme and demonstrate the untethered polymorphic actuation of the proof-of-concept device. The ultrasonic actuation is enabled through converting the incoming ultrasonic energy to thermal energy by the Joule heating. The temperature increase triggers shrinking of the thermally responsive hydrogel/polymer bimorph. By employing two ultrasonic receivers with different resonant frequencies (frequency coding), we demonstrated 4 different motions of the actuator.

Self powered hand handled biomedical instruments are of demand in industries. Piezoelectric energy harvester is one of the most efficient energy harvesters now in use to harvest electrical energy from the ambient mechanical energy sources such as touch, small vibrations etc. This unique property of the piezoelectric materials opens a wide area of applications in the fields like sensors, actuators etc. A bimorph cantilever based piezoelectric energy harvester is of great interest due to the sustained vibrations that can be produced on single input pressure by the user. In this paper we propose on material based design strategy of this cantilever structure for energy harvesting by piezoelectric effect. The study is carried out by replacing the electrode material with Structural Steel, Gold (Au) and Copper (Cu). The piezoelectric materials like PZT 5A (Lead Zirconate Titanate), ZnO (Zinc Oxide), ZnS (Zinc Sulphide), Bismuth Germanate (BGO) are used in combination with the electrode materials and their performance is evaluated.

This chapter explores the potential of vibration energy harvesting from structures leveraging flexoelectricity (i.e., strain gradient-induced polarization) and presents analytical modeling and analysis results for next-generation submicron scale energy harvesters. At such small geometric scales, flexoelectricity, as a gradient effect, enables significant electromechanical behavior even in nonpiezoelectric dielectric materials, while it enhances the electromechanical coupling in piezoelectric ones. In particular, energy harvesting is a potential future application area of flexoelectricity to enable ultra-low-power nanoscale devices by converting vibrations into electricity. The focus of this chapter is first placed on bending vibration of centrosymmetric cantilevers, such as a monolayer STO (Strontium Titanate) cantilever. An electroelastodynamic framework is presented and analyzed for flexoelectric power generation from strain gradient fluctuations in centrosymmetric dielectrics, by accounting for the presence of a finite electrical load across the surface electrodes as well as two-way electromechanical coupling, and capturing the size effect. Following recent efforts on the converse flexoelectric effect in finite samples, the proposed model properly accounts for a thermodynamically consistent, symmetric two-way coupling, i.e., the direct and converse effects. In addition to the electromechanical frequency response functions, the transverse mode flexoelectric coupling coefficient (a direct measure of energy conversion) is obtained analytically; its dependence on the cantilever thickness and a material figure of merit is shown. The modeling framework is then extended to noncentrosymmetric configurations, such as bimorph cantilevers made from Barium Titanate (BTO), to understand the interaction between flexoelectricity and piezoelectricity for different thickness levels from mm-scale to nm-scale, with a focus on resonant energy harvesting. The level of enhancement in the overall electromechanical coupling due to flexoelectricity with reduced thickness is quantified.

Braille system is a universal code for visually impaired people to read and visualize image by using their haptic sense without using their eye. Over the few centuries, with the advent of technology, numerous assistive technologies have been developed and widely accessible for the visually impaired community. However, for developing countries such as Malaysia, educational braille based and current assistive technology for visually impaired people to read and visualize such as electronic braille display still lacking. This is because a piezo bimorph actuator actuates most of the braille cell used in the commercialize braille display. This system not only complex due to arrangement of the piezo strip, but it also expensive to produce a reliable system. Moreover, it’s braille cell also has a limited feature, where it can support to display single-line sentence only due to the arrangement and nature of piezo bimorph. This paper aims to develop an electromagnetic actuator for braille cell, where it can support multiple lines of sentence, cost-effective and has the same performance as commercial braille display. Next, to determine suitable design parameters and evaluates the performance of the fabricated braille cell. An experiment is done with three levels of factors, one for the number of turns and the other is diameter which are 100, 200, and 300 turns and 0.1, 0.3, and 1.0mm. The result shows, regardless of wire diameter for coil, the minimum current required to lift the dot will remain the same for the same number of turns. A final number of turns and diameter selected is 300 turns and 0.1mm and required minimum value of current 0.08A to lift the dot. The study approaches towards the development of braille cell that used alternative actuator, which is an electromagnetic actuator to achieve more compact braille display while able to display multiline sentence.

Soft materials that respond to wireless external stimuli are referred to as ""smart"" materials due to their promising potential in real-world actuation and sensing applications in robotics, microfluidics, and bioengineering. Recent years have witnessed a burst of these stimuli-responsive materials and their preliminary applications. However, their further advancement demands more versatility, configurability, and adaptability to deliver their promised benefits. Here, a dual-stimuli-responsive soft bimorph material with three configurations that enable complex programmable 3D shape-morphing is presented. The material consists of liquid crystal elastomers (LCEs) and magnetic-responsive elastomers (MREs) via facile fabrication that orthogonally integrates their respective stimuli-responsiveness without detrimentally altering their properties. The material offers an unprecedented wide design space and abundant degree-of-freedoms (DoFs) due to the LCE's programmable director field, the MRE's programmable magnetization profile, and diverse geometric configurations. It responds to wireless stimuli of the controlled magnetic field and environmental temperature. Its dual-responsiveness allows the independent control of different DoFs for complex shape-morphing behaviors with anisotropic material properties. A diverse set of in situ reconfigurable shape-morphing and an environment-aware untethered miniature 12-legged robot capable of locomotion and self-gripping are demonstrated. Such material can provide solutions for the development of future soft robotic and other functional devices., European Union (EU) Horizon 2020; European Research Council (ERC) Advanced Grant SoMMoR Project; Max Planck Society; Alexander von Humboldt Foundation

Currently, two AO systems are operated at Subaru Telescope: AO188, which is a facility AO system, and SCExAO, which is a PI-type ExAO system operated behind AO188. In the next 5 year, large-scale upgrades are performed on AO188 for improving the AO performance and operation of AO188 and SCExAO and for the technical demonstration toward the future wide-field ULTIMATE-Subaru GLAO system at Subaru and an ExAO system at TMT, PSI. We are planning to upgrade the real-time control system, the LGS system, and bimorph DM. Also, a new NIR WFS, a LTAO WFS unit, and a beam-switching system will be installed into the Nasmyth IR platform. The installation of the LTAO WFS unit is a part of the ULTIMATE-START project, which implement a LTAO mode into AO188 and demonstrates technologies for the ULTIMATE-Subaru GLAO system. ULTIMATE-Subaru project aims at developing a next-generation, wide-field GLAO system and wide-field NIR instruments for Subaru Telescope, whose first light will be in FY2025.

Increasing of the focusing efficiency of partially coherent laser radiation propagated through a scattering medium was investigated. To improve focusing of scattered laser beam, we applied bimorph deformable mirror with 48 control electrodes and LCOS-SLM with 1920×1080 pixels resolution and compared their efficiencies. We used 5 mm thick glass cuvette filled with the suspension of 1 um polystyrene microspheres, diluted in distilled water. The concentration of scatterers were varied from 105 to 106 mm-3 . According to principle of similarity a medium with such parameters can be considered as an equivalent to the middle-density fog layer with the length ranging from 300 meters up to 5 kilometers. Numerical and experimental investigation of the focusing improvement showed that it is possible to increase the peak intensity of the focal spot up to 60%.

Bimorph deformable mirror for correction of low-order aberrations of laser radiation was manufactured. Two technologies were used to develop this wavefront corrector: laser engraving technology and ultrasonic welding technology. The mirror has aperture of 10 mm and 13 control electrodes. The thickness of the wavefront corrector is 1 mm. The applied voltages took values in the range from -150 to +200 V. The stroke of the mirror for one electrode was equal to 1 micron (P-V). The first resonant frequency was found at 10.8 kHz. Such mirror can be used in closed-loop adaptive optical system with speed about 1.1 kHz.

The development of laser technique and various applications of laser radiation requires the use of devices that can modify as well as correct for the wavefront of laser beams. In these cases, the use of deformable mirrors is simply very important. In the high-power laser setups, the task of correction of laser aberrations assumes the use of thermally stabilized optical elements. We consider that two types of wavefront correctors are the most well-suitable for such an application: bimorph deformable mirrors and stacked-actuator (SADM) ones. Bimorph deformable mirrors proved their reliability and could be used in high-power industrial lasers. They can perfectly correct for low-order and are simple in manufacturing. On the contrary stacked-actuator mirror can reproduce high-order wavefront aberrations and thus have high spatial resolution of control elements and might be applied in fast adaptive optical systems to correct for laser radiation distributed through turbulent media.

Inspired by bells, a kinetic energy harvester was designed to scavenge energy from ambient vibrations and winds in different directions. It is constructed by supporting a bracket, surrounded by six cantilevered bimorphs, with a spring. Under excitations of base movements and airflows, the bracket vibrates and causes a steel bead in it to roll and to strike the bimorphs, making the bimorphs vibrate and produce electricity. A prototype was tested on an electromagnetic shaker and the experimental results showed that the prototype is good at scavenging two dimensional vibrations, with the minimum total output power of about 0.85 times the maximum value when the vibration direction changes in the horizontal plane. In addition, the prototype was tested in a small wind tunnel and the experiments verified that the device can collect wind energy effectively when a cardboard cover is added onto it. With the increase of the wind speed, it experienced the transverse vibrations, the rotational vibrations and the back-and-forth vibrations, respectively. The output power of one bimorph is about 109.4 μW when wind speed is 10 m/s.