Electromechanical Coupling Research Articles

Advancing cardiac 3D organoid-on-chip: integrating iPSC-derived MELAS syndrome models to study electromechanical synchronicity and cardiac memory using contactless technology

Abstract Background Mitochondrial DNA mutations affect 1:5000 newborns, posing life-threatening risks, especially to high-energy organs such as the brain, heart, and muscles. Mortality rates can reach 71% when cardiomyopathy is present. MELAS syndrome (Mitochondrial Encephalopathy with Lactic Acidosis and Stroke-like Episodes), primarily affecting protein synthesis (MTTL1 gene, tRNALeu(UUR)), disrupts the electron transport chain complex I and is associated with cardiac conduction defects and hypertrophy. Manifesting symptoms typically appear between ages 3 and adulthood, presenting a complex clinical scenario. Human induced pluripotent stem cells (hiPSCs) offer a unique platform for studying cardiac manifestations of this disease when differentiated into cardiomyocytes. Purpose We adopted a highly adaptable in-vitro model, organized in 3D cardioids, to explore potential impairments in electromechanical coupling of cells. Methods We utilized hiPSCs carrying the MELAS mutation and their respective isogenic controls differentiated into cardiomyocytes, cultured in 3D cardioids. Electromechanical coupling was assessed using laser-poration technology combined with video kinematics evaluation under various stimulation patterns. Results Morphological analysis revealed a statistically significant reduction in the diameter of MELAS cardioids compared to the isogenic 3D structures (368±17.15 μm vs. 527±36.76 μm). In a spontaneous regimen, MELAS samples exhibited higher beating frequency (0.88±0.28 Hz vs. 0.17±0.05 Hz) and contractile speed (99.35±39.11 μm/s vs. 33.46±5.57 μm/s). Additionally, the response to different electric field stimulation protocols varied significantly, with the isogenic cell line showing better adaptation to sinusoidal stimuli than the pathological one, characterized by rectangular monophasic stimuli. Laser-poration technology, combined with MEA chips and video kinematic evaluation, revealed modulation of electromechanical coupling, affecting action potential upstroke and duration, reducing contraction velocity, and altering electromechanical delay. Furthermore, MELAS hiPSCs and primary cardiomyocytes exhibited reduced protein levels of various OXPHOS subunits (SDHB, ATPB, and COX IV) compared to isogenic controls. The mutated cell line also showed increased ROS production in non-stimulated samples compared to stimulated ones (1.3-fold vs. 1.2-fold), with this difference magnifying after 24 hours from stimulation (1.8-fold vs. 1.3-fold). Conclusions This study characterizes MELAS hiPSCs differentiated into cardiac organoids, offering insight into the cardiac aspect of this complex syndrome. Our findings deepen understanding of the syndrome's cardiac impact and response to extracellular stimuli, potentially benefiting affected tissues. This research defines critical physiological and kinematic parameters for MELAS, paving the way for future investigations.

Vibration Suppression and Energy Harvesting of Nonlinear Energy Sink-Based Piezoelectric System with Combined Damping and Bistability Properties for Nonlinear Oscillator

Nonlinear energy sink (NES) as a new type of dynamic absorber has received widespread attention due to its broadband vibration suppression capability, but it has a certain requirement of energy triggering threshold. In this work, a bistable NES-based piezoelectric system with combined damping (BCPNES) and low threshold requirement is proposed. Electromechanical-coupled equations for the nonlinear oscillator coupled with BCPNES (NO-BCPNES) are established. The vibration suppression and vibration energy harvesting performance for the coupled system are investigated numerically and analytically. The frequency–energy plots of the conservative system are investigated using the complex-variable averaging method and the electromechanical decoupling method. The influence of circuit parameters on the target energy transfer threshold and harvested energy is discussed through the equivalent stiffness and damping of the circuit. The vibration suppression performance and the target energy transfer characteristics are analyzed in terms of the time–history response, the time–frequency response and the slowly varying dynamic flow, respectively. The results show that the electromechanical coupling coefficient affects the skeleton curve of frequency–energy plots in the form of equivalent stiffness. The NO-BCPNES system exhibits higher energy dissipation performance and better targeted energy transfer form under various excitations. From the phase perspective, NES-based piezoelectric system achieves vibration suppression of the main structure through the phase locking phenomenon. The mechanism of the influence of piezoelectric device parameters on the energy harvesting performance of the systems is clarified.

Functional bias of contractile control in mouse resistance arteries

Constrictor agonists set arterial tone through two coupling processes, one tied to (electromechanical), the other independent (pharmacomechanical) of, membrane potential (VM). This dual arrangement raises an intriguing question: is the contribution of each mechanism (1) fixed and proportionate, or (2) variable and functionally biased. Examination began in mouse mesenteric arteries with a vasomotor assessment to a classic Gq/11 (phenylephrine) or Gq/11/G12/13 (U46619) agonist, in the absence and presence of nifedipine, to separate among the two coupling mechanisms. Each constrictor elicited a concentration response curve that was attenuated and rightward shifted by nifedipine, findings consistent with functional bias. Electromechanical coupling preceded pharmacomechanical, the latter’s importance rising with agonist concentration. In this regard, ensuing contractile and phosphorylation (CPI-17 & MYPT1 (T-855 & T-697)) measures revealed phenylephrine-induced pharmacomechanical coupling was tied to protein kinase C (PKC) activity, while that enabled by U46619 to PKC and Rho-kinase. A complete switch to pharmacomechanical coupling arose when agonist superfusion was replaced by pipet application to a small portion of artery. This switch was predicted, a priori, by a computer model of electromechanical control and supported by additional measures of VM and cytosolic Ca2+. We conclude that the coupling mechanisms driving agonist-induced constriction are variable and functionally biased, their relative importance set in accordance with agonist concentration and manner of application. These findings have important implications to hemodynamic control in health and disease, including hypertension and arterial vasospasm.

Piezo-VFETs: Vacuum Field Emission Transistors Controlled by Piezoelectric MEMS Sensors as an Artificial Mechanoreceptor with High Sensitivity and Low Power Consumption.

As one of the most promising electronic devices in the post-Moore era, nanoscale vacuum field emission transistors (VFETs) have garnered significant attention due to their unique electron transport mechanism featuring ballistic transport within vacuum channels. Existing research on these nanoscale vacuum channel devices has primarily focused on structural design for logic circuits. Studies exploring their application potential in other vital fields, such as sensors based on VFET, are more limited. In this study, for the first time, the design of a vacuum field emission transistor (VFET) coupled with a piezoelectric microelectromechanical (MEMS) sensing unit is proposed as the artificial mechanoreceptor for sensing purposes. With a negative threshold voltage similar to an N-channel depletion-mode metal oxide silicon field effect transistor, the proposed VFET has its continuous current tuned by the piezoelectric potential generated by the sensing unit, amplifying the magnitude of signals resulting from electromechanical coupling. Simulations have been conducted to validate the feasibility of such a configuration. As indictable from the simulation results, the proposed piezoelectric VFET exhibits high sensitivity and an electrically adjustable measurement range. Compared to the traditional combination of piezoelectric MEMS sensors and solid-state field effect transistors (FETs), the piezoelectric VFET design has a significantly reduced power consumption thanks to its continuous current that is orders of magnitude smaller. These findings reveal the immense potential of piezoelectric VFET in sensing applications, building up the basis for using VFETs for simple, effective, and low-power pre-amplification of piezoelectric MEMS sensors and broadening the application scope of VFET in general.

Research on operating characteristics of V-shaped ultrasonic motor based on improved electromechanical coupling model

Abstract As a complex electromechanical coupling system, evaluating the motion characteristics of an ultrasonic motor via an accurate theoretical model is challenging due to the strong coupling between its electrical and mechanical properties. To address this issue, the paper first establishes a complete dynamic model of the V-shaped ultrasonic motor (VUSM). In contrast to the traditional dynamic model, the proposed model incorporates the centroid vibration of the stator and applies the weighted residual method to reduce the computational complexity by simplifying the dynamic model from infinite-dimensional degrees of freedom to two degrees of freedom. Subsequently, the finite element method is employed to determine the vibration mode of the stator structure and derive the two-phase operational mode of the motor. Using these two-phase working modes, the model is then solved to predict the motor's output characteristics under any operational condition. Furthermore, an electrical model accounting for preload nonlinearity was developed based on the dynamic model and compared with the model without considering preload nonlinearity, supported by experimental verification. The findings demonstrate that the established dynamic model and electrical model can accurately simulate the changing laws of the input and output characteristics of the motor, which provides assistance for the subsequent operation status evaluation of the motor and fault diagnosis during operation.

Torsional vibration suppression and electromechanical coupling characteristics of electric drive system considering misalignment

Torsional vibration suppression and electromechanical coupling characteristics of electric drive system considering misalignment

A spurious-free SAW filter employing a novel transducer structure on bulk LiNbO3 substrates

In order to cope with the ubiquitous wireless connections and the rapid transmission of data in communication systems, surface acoustic wave filters are required to have high performance. With a large electromechanical coupling coefficient (K2), conventional bulk 64°YX-LiNbO3 substrates are attractive for low-cost mass production of surface acoustic wave (SAW) resonators. However, the influence of the transverse modes restricts their practical application. In this work, a novel and simple tilted transducer is fabricated, and successfully achieved spurious-free passband SAW filters based on 64°YX-LN piezoelectric substrates. In this work, the transverse modes suppression method is theoretically studied and designed, and the effectiveness of the energy concentrated structure is verified. The optimal tilt IDT angle for eliminating the influence of transverse modes in Al/64 °YX-LN structure is about 6°. Subsequently, based on the above research, three types of tilted resonators were designed and fabricated, which not only verified the reliability of the aforementioned results but also enhanced the performance of the devices, compensating for the deficiency caused by the reduction of the Q factor due to the tilted structure. Finally, based on the double busbar tilted structure, a SAW filter was designed, which has a large 3 dB fractional bandwidth (FBW) and a spurious-free passband. The SAW filter designed in this work has low cost and excellent performance, and can be mass produced. In the field of low-cost RF devices, this work contributes to maintaining the competitive advantage of SAW technology.

Performance enhancement of galloping wind energy harvesting via bio-inspired V-shaped blade

ABSTRACT Galloping wind energy harvesting has promising applications in future distributed self-powered low-power devices. A novel V-shaped blade is figured out from Palm leaf galloping. The enhancement of galloping oscillation from the bio-inspired V-shaped blade is evaluated. The galloping wind energy harvester (WEH) with a V-shaped blade is developed by electro-mechanical modeling, finite element simulation, ground vibration tests, and wind tunnel tests. It is found that the structural damping, effective electro-mechanical coupling coefficient, and V-shape included angle have big effects on the harvesting performance. The cut-in wind speed of WEH is below 3 m/s. With an included angle of 115° and a wind speed of 6.5 m/s, the output voltage is 4.48 V and the power density is 90.00 μW/cm3. The V-shaped blade harvester exhibits a 151.69% increase in output voltage and a 575.00% increase in power density compared to the traditional brick blade (square cross-section) harvester. Tests indicate that the output frequency remains stable at the structural resonant despite increasing wind speed. This study provides insights into enhancing galloping oscillation and wind energy harvesting efficiency by optimizing the aerodynamic shape of vortex shedding bluffs.

Electromechanical coupling modeling and fractional-order control of the seeker stabilization platform

To address the electromechanical coupling and multi-source disturbance problems of the seeker stabilized platform, this paper constructs an electromechanical coupling model of the seeker stabilized platform based on the Lagrange-Maxwell equation. To mitigate the influence of electromechanical coupling on the control performance of the seeker, a super-twisting controller based on a fractional-order terminal sliding mode surface (FOSTSMC) is proposed. Additionally, to handle various disturbances in the system, this paper introduces a method that combines the extended state observer (ESO) with the proposed controller to enhance the system’s stability and anti-disturbance performance. The Lyapunov function is designed to prove that the proposed controller can reach a convergence state within finite time. Finally, the proposed control method is compared with PID control, fuzzy PID control, linear sliding mode control, and super spiral control combined with a disturbance observer (DOB). Multiple simulation experiments demonstrate that, under the influence of electromechanical coupling and multi-source disturbance, the FOSTSMC-ESO significantly improves the stability and anti-disturbance performance of the seeker stabilization platform.

Research on the mechanism of electromechanical coupling response of pulse power multilayer ceramic capacitors under high impact and high voltage discharge composite environment

Pulse power multilayer ceramic capacitors (pulse power-MLCC) are commonly used in complex composite environments with high overload and high voltage due to their large size and capacitance. In order to study the electromechanical coupling response characteristics of pulse power-MLCC in high-impact and high-voltage composite environments, a split Hopkinson pressure bar (SHPB) testing system was used to simulate high impact. The mechanical and electrical parameters of pulse power-MLCC were collected under high-impact and voltage environments, and the capacitance changes at different impact velocities were obtained. The stress wave transmission characteristics of pulse power-MLCC were studied by combining numerical simulation and theoretical analysis, and the structural deformation of ceramic dielectric under impact stress was analyzed. The relationship between the capacitance and DC bias of the capacitor was analyzed. A capacitance calculation model for pulse power-MLCC in an electromechanical coupling environment was established, revealing the electromechanical coupling mechanism of pulse power-MLCC.

Multivariable switching control of a compliant piezoelectric microgripper with force/position interaction interferences

This paper presents multivariable switching control of a piezoelectric microgripper regarding its output displacement, gripping force, and manipulated position. Unlike existing microgripper control, it simultaneously regulates force/position variables. Meanwhile, force/position interaction interferences and signal itself overshooting are suppressed. Firstly, a symmetrical microgripper with two independent gripping arms is introduced. Then, a generalized dynamic model is established by considering structural dynamics, electromechanical coupling, and force/position interaction. After that, multivariable switching control is proposed to achieve clamp-carry-release manipulation using dual-input and dual-output (DIDO) perturbation displacement and force/position controllers. Finally, various switching experiments are conducted, demonstrating that force/position interaction interferences are reduced by 83.76 % and 87.51 %, and interference-suppression time is shortened from 0.86 s and 0.70 s to 0.49 s and 0.41 s. Also, overshoots of gripping force and position are eliminated with a smaller settling time. The proposed multivariable switching control exhibits superior regulation performance, guaranteeing manipulation accuracy and stability.

Theoretical investigation of Rayleigh-type surface acoustic waves with high electromechanical coupling coefficient in c-axis-tilted ScAlN film/3C-SiC substrate structure

Surface acoustic wave (SAW) resonators are essential components of mobile communication technology. Advanced performance SAW resonators are needed to support beyond fifth-generation mobile communication technology, which aims to achieve unprecedentedly high data rates and low latency using wide frequency bands in the RF spectrum. This study theoretically investigates the propagation characteristics of a non-leaky Rayleigh-type SAW (RSAW) propagating in a c-axis-tilted ScAlN film/3C-SiC substrate structure. By appropriately selecting the c-axis tilt angle and the film thickness of the ScAlN film, a high electromechanical coupling coefficient (K2) value was obtained in the second-mode RSAW (Sezawa wave). The maximum K2 value for the Sezawa wave was 8.03%, with a phase velocity of 7456 m/s and a power flow angle of 0° under the structural conditions where the K2 value was maximized. These properties offer significant advantages for achieving wide frequency bands, high operating frequencies, and ease of design for SAW resonators. The structural conditions under which good propagation characteristics were obtained in the Sezawa waves were found to coincide with the conditions that maximize the electromechanical coupling coefficient of the quasi-longitudinal wave in the ScAlN film, and a significant increase in the shear vertical component of Sezawa wave particle displacement was observed. Additionally, ScAlN films with a 40% Sc concentration can be fabricated using sputtering and molecular beam epitaxy. Recent advancements have reported the production of high-quality 3C-SiC wafers and large 3C-SiC film/silicon wafers. Therefore, the c-axis-tilted ScAlN film/3C-SiC substrate structure shows great potential as a candidate for next-generation SAW resonators.

Second‐order computational homogenization of flexoelectric composites

AbstractFlexoelectricity shows promising applications for self‐powered devices with its increased power density. This paper presents a second‐order computational homogenization strategy for flexoelectric composite. The macro‐micro scale transition, Hill–Mandel energy condition, periodic boundary conditions, and macroscopic constitutive tangents for the two‐scale electromechanical coupling are investigated and considered in the homogenization formulation. The macrostructure and microstructure are discretized using triangular finite elements. The second‐order multiscale solution scheme is implemented using ABAQUS with user subroutines. Finally, we present numerical examples including parametric analysis of a square plate with holes and the design of piezoelectric materials made of non‐piezoelectric materials to demonstrate the numerical implementation and the size‐dependent effects of flexoelectricity.

Love wave propagation on nano-sized layered piezoelectric plate clamped on micropolar substrate

This research paper investigates the complex dynamics of Love wave propagation on a piezoelectric plate situated atop a micropolar elastic half-space having imperfect interface. The study delves into the multifaceted effects of flexoelectricity, micro-inertia, guiding layer thickness, and interfacial imperfection on the characteristics of Love waves. The electromechanical coupling factor which is significant in analyzing SAW device performances is also studied. Variable separable method is used to solve the governing equations and desired solution is obtained analytically. The findings contribute to a deeper understanding of Love wave propagation in complex elastic structures and development of advanced sensors and communication technologies.

Electromechanical coupling optimization for a sandwich beam activation using piezoceramics

Sandwich beams composed of two stiff carbon fiber skins and a viscoelastic core are often used to passively dissipate energy through the activation of shearing in a specific frequency range. Semi-active or active energy dissipation can be made possible on those structures adding piezoelectric patches, coupling mechanical vibration energy and electrical energy. J.L. Guyader et al. [jsv, 1978] theorized a frequency dependent equivalent dynamic model of a sandwich structure, recently extended to the homogenization of anisotropic multi-layers by F.Marchetti et al. [jsv, 2020]. This frequency-dependent stiffness of the beam has to be taken into account in the piezoceramic thickness definition in order to optimize the global electromechanical coupling coefficient. An analytical model is derived from the works of F.Marchetti et al. and adapted to predict the first vibration mode of a finite cantilever beam instrumented with a piezoelectric patch. The electromechanical coupling evolution is then calculated with the proper boundary conditions and for different PZT ceramic thicknesses. This model is furtherly used to define the best transducer configuration for a given sandwich structure beam.

Intertwined Flexoelectricity and Stacking Ferroelectricity in Marginally Twisted hBN Moiré Superlattice.

Moiré superlattices in twisted van der Waals homo/heterostructures present a fascinating interplay between electronic and atomic structures, with potential applications in electronic and optoelectronic devices. Flexoelectricity, an electromechanical coupling between electric polarization and strain gradient, is intrinsic to these superlattices because of the lattice misfit strain at the atomic scale. However, due to its weak magnitude, the effect of flexoelectricity on moiré ferroelectricity has remained underexplored. Here, the role of flexoelectricity in shaping and modulating the moiré ferroelectric patterns in twisted hBN homojunction is unveiled. Enhanced flexoelectric effects induce unique stacking ferroelectric domains with hollow triangular structures. Interlayer bubbles influence domain shape and periodicity through local electric field modulation, and tip-stress enables the reversible manipulation of domain area and polarization direction. These findings highlight the impact of flexoelectric effects on moiré ferroelectricity, offering a new tuning knob for its manipulation.

Vibration reduction of an electric vehicle heat exchanger by controlling the polarization of its ferroelectric ceramics

The growing requirements in terms of CO2 emissions reduction in transports renders necessary the development of new electric traction technologies. This results in new technical constraints for equipment manufacturers, forcing them to reduce the acoustic emissivity of their new products inside and outside vehicles. Heat exchangers for electric cars are part of this new product category. High voltage supplied by the battery of electrical vehicles requires introduction of a new energy conversion process and technology. To this end, components based on ceramics containing barium titanate (BaTiO3) with high electrocaloric coupling properties are selected to provide the heating function. Baryum titanate is ferroelectric. This category of materials is subjected to piezoelectric and electrostrictive effects. The vibrations induced in the components (rods) containing the BaTiO3 ceramics are transmitted through the system, and cause undesired acoustic radiation. This coupling is a suffered effect and is not taken into account in the integration process during the rods manufacturing. In this study, an experimental characterization is proposed to identify the involved electromechanical coupling coefficients. Numerical simulations of the vibrations induced by BaTiO3 are carried out and used to study the possibility of attenuating them by controlling the polarisation of the ceramics or by geometric modifications.

Fundamental study on the difference between materials and vibration conditions in piezoelectric vibration power generation using electromechanical coupling phenomena

Conventionally, vibration energy and sound energy are emitted as noise and vibration. We have proposed a system that converts the vibration of the plate into energy. In this study, a circular plate of constant thickness, on which a piezoelectric element was installed, was adopted as the host structure of an energy-harvesting system. The plate was supported at its elastic end, which was intermediate between simple and clamped supports, and was subjected to a harmonic point force. The piezoelectric performance of the system was highly dependent on the vibration characteristics of the plate. Regarded as one of the representative vibrational characteristics, the natural frequency of the plate was affected by the materials, excitation positions, and vibration modes of the plate. Therefore, the plate materials varied the natural frequency, thus affecting the conversion of vibration energy into electrical energy through the piezoelectric effect. In this study, we investigated plates made of selected materials commonly used in industry and tested different excitation conditions. As the result, we clarified that the proposed system is almost unaffected by the material of the plates, and it was shown to be useful.

On-chip stimulated Brillouin scattering via surface acoustic waves

Surface acoustic wave devices are ubiquitously used for signal processing and filtering, as well as mechanical, chemical, and biological sensing and show promise as quantum transducers. While surface acoustic waves (SAWs) are primarily excited and driven using electromechanical coupling and interdigital transducers, there is a strong desire for novel methods that enable the coherent excitation and detection of SAWs all-optically interfacing with photonic integrated circuits. In this work, we numerically model and experimentally demonstrate SAW excitation in integrated photonic waveguides made from GeAsSe glass via backward stimulated Brillouin scattering (SBS). We measure a Brillouin gain coefficient of 203 W−1 m−1 for the surface acoustic resonance at 3.81 GHz, with a linewidth narrowed to 20 MHz. Experimental access to this new regime of SBS not only opens up opportunities for novel on-chip sensing applications by harnessing the waveguide surface but also paves the way for strong Brillouin interactions in materials lacking sufficient acoustic guidance in the waveguide core, as well as the excitation of SAWs in non-piezoelectric materials.

Gold as a Promising Electrode Material for LiNbO3-on-Insulator (LNOI) SH-SAW Resonators: An Experimental Study.

The need for wideband radio frequency front ends (RFFEs) with next-generation wireless protocols highlights the importance of electromechanical coupling [Formula: see text]. The hetero acoustic layered (HAL) surface acoustic wave (SAW) resonator with aluminum (Al) electrodes has shown superior performance compared to conventional SAW devices. Despite gold (Au) having excellent conductivity and stable properties, its high acoustic absorption and low phase velocity have made it less favorable for electrodes. This work demonstrates that high-performance shear horizontal (SH)-SAW resonators can be fabricated on the lithium niobate-on-insulator (LNOI) platform using a setup specifically designed for an Au electrodes. Experimental validation shows that the device achieves a high quality factor (Q) over 870, excellent [Formula: see text] up to 40%, and operates around 765 MHz. Unwanted transverse spurious modes are suppressed through adequate electrode design, and the temperature stability of LNOI SH-SAW with Au electrodes is discussed. This study highlights gold's potential as an electrode material for high [Formula: see text], clean spectrum, and wideband applications.