Flexible and lightweight polymer-ceramic composites are actively pursued for mechanical energy harvesting applications. In this work, polyvinylidene fluoride (PVDF)-based composite films incorporating sol-gel synthesized (Ba,Ca)(Sn,Ti)O3 (BCST; Ba0.91Ca0.09Sn0.08Ti0.92O3) ceramic fillers were fabricated using a cost-effective solution-casting method and systematically investigated. Transmission electron microscopy (TEM) confirmed BCST particle sizes in the range of 300–600 nm. Multiscale characterization revealed a significant role of filler–polymer interfacial interactions in governing the functional properties. Microstructural and spectroscopic analyses indicate that BCST particles act as heterogeneous nucleation centers, promoting the formation of electroactive β- and γ-phases in PVDF. The composite films exhibited enhanced dielectric permittivity while maintaining low dielectric loss, governed by dipolar and interfacial polarization mechanisms. Macroscopic ferroelectric and piezoelectric properties enhanced with BCST content, with maximum polarization (Pmax) and piezoelectric charge coefficient d33 reaching a value of ~3.8 μC/cm2 and ~ 22 pC/N, respectively, for the composite with a filler concentration of 10 wt%. Nanoscale switching and piezoelectric activity were confirmed using piezoresponse force microscopy (PFM). Nanoindentation measurements revealed increased hardness and modulus, indicating improved mechanical robustness due to BCST incorporation.Under low-frequency bending excitation at a resonance frequency of ~4.4 Hz, the cantilever-beam-type energy harvester delivered a maximum output voltage of ~0.83 V and a volumetric power density of ~0.75 μW/cm3 for the composite with 10 wt% BCST. These results demonstrate that BCST is an effective lead-free ferroelectric filler for enhancing the functional properties of PVDF–BCST polymer composites, highlighting their potential for low-frequency, low-power energy harvesting applications.

Flexible and lightweight polymer-ceramic composites are actively pursued for mechanical energy harvesting applications. In this work, polyvinylidene fluoride (PVDF)-based composite films incorporating sol-gel synthesized (Ba,Ca)(Sn,Ti)O3 (BCST; Ba0.91Ca0.09Sn0.08Ti0.92O3) ceramic fillers were fabricated using a cost-effective solution-casting method and systematically investigated. Transmission electron microscopy (TEM) confirmed BCST particle sizes in the range of 300–600 nm. Multiscale characterization revealed a significant role of filler–polymer interfacial interactions in governing the functional properties. Microstructural and spectroscopic analyses indicate that BCST particles act as heterogeneous nucleation centers, promoting the formation of electroactive β- and γ-phases in PVDF without requiring additional treatments. The composite films exhibited enhanced dielectric permittivity while maintaining low dielectric loss, governed by dipolar and interfacial polarization mechanisms. Macroscopic ferroelectric hysteresis measurements showed improved polarization behavior, reaching a maximum polarization of ~3.8 μC/cm2 at an optimal filler concentration of 10 wt%. Nanoscale switching and piezoelectric activity were confirmed using piezoresponse force microscopy (PFM). Nanoindentation measurements revealed increased hardness and modulus, indicating improved mechanical robustness due to BCST incorporation. Under low-frequency bending excitation at a resonance frequency of ~ 4.4 Hz, the cantilever-beam-type energy harvester delivered a maximum output voltage of ~ 0.83 V and a volumetric power density of ~ 0.75 μW/cm3 for the composite with 10 wt% BCST. These results demonstrate that BCST is an effective lead-free ferroelectric filler for enhancing the functional properties of PVDF-BCST polymer composites, highlighting their potential for low-frequency, low-power energy harvesting applications.

Triboelectric and piezoelectric energy harvesters can hardly power most microelectronic systems. Rotational electromagnetic harvesters are very promising alternatives, but their performance is highly dependent on the varying mechanical sources. This study presents an innovative approach to significantly increase the performance of rotational harvesters, based on dynamic coil switching strategies for optimization of the coil connection architecture during energy generation. Both analytical and experimental validations of the concept of self-adaptive rotational harvester were carried out. The adaptive harvester was able to provide an average power increase of 63.3% and 79.5% when compared to a non-adaptive 16-coil harvester for harmonic translation and harmonic swaying excitations, respectively, and 83.5% and 87.2% when compared to a non-adaptive 8-coil harvester. The estimated energy conversion efficiency was also enhanced from ~80% to 90%. This study unravels an emerging technological approach to power a wide range of applications that cannot be powered by other vibrationally driven harvesters.

The dynamic behavior of a vibrational electromagnetic generator using a magnetic levitation architecture was theoretically and experimentally studied in great detail, when operating under a wide range of three-dimensional excitations. We developed a complete rigorous physical model from first principles based on the theory of electrodynamics of continua, centered on the laws of electrodynamics and balance of mass, linear momentum, angular momentum, energy and entropy. Local electromagnetic and gravitational body forces, couples and powers were considered, and the surface tractions were divided into constraint and friction components, as well as those due to external mechanical energy sources. The balance of linear momentum, angular momentum and circuit equations resulted in up to 13 non-linear differential equations describing the dynamics of the levitating-magnet and container, relating input forces and torques with output displacement, constraint forces and voltage. The balance of energy yielded a consistent equivalence between the time rate of change of the internal kinetic and potential energies of the generator and the output power, associated with the external circuit, Ohmic losses and friction losses, as well as the input mechanical power being supplied to the system by the environment. Both the input and output powers were proven to tend to increase equally when operating the generator under resonant conditions. The levitating generator was shown to be sensitive to axial translational and centrifugal inertial forces, each one effectively resulting in a uni-stable or bi-stable system. The dynamical response yielded multiple initial conditions dependent steady-states, hysteretic frequency output and chaotic characteristics. Relevant guidelines to optimize the energy conversion efficiency of energy harvesters are provided. This model was validated by experimental tests, including general 3D motions combining translations and rotations: cross-correlations exceeding 90% were achieved. Such Newtonian and Langrangian modelling approaches hold great potential to be easily adapted to a wide range of other electromagnetic generators, with multiple degrees-of-freedom and operating under various environments, such that significant advances in energy technologies can be supported.

The electric efficiency of vibrational electromagnetic generators is highly dependent on their ability to ensure effective adaptability to uncertain and irregular dynamics of mechanical energy sources. Such adaptive ability demands a planning operation considering future information of the highly nonlinear dynamics of these generators and mechanical excitations patterns. High accurate energy predictions are then mandatory for high energy generation efficiencies. However, on the one hand, high prediction accuracy by analytical modelling from first principles requires high modelling complexity; on the other hand, artificial intelligence models ensuring high prediction accuracy have not yet been explored to enhance the performance of these generators, even though their pre-training holds potential to significantly reduce the energy production costs. We here provide a multifaceted study highlighting the synergies between analytical and artificial intelligence modelling for optimizing the efficiency of vibrational-powered electromagnetic generators. Two main innovations are introduced: (1) development and experimental validation of a time-series forecasting artificial intelligence model based on the deep deterministic policy gradient method; (2) validation of a pre-training scenario by analytical modelling-> artificial intelligence modelling synergy. Both the analytical and artificial intelligence models were able to provide high prediction accuracies to periodic and random 3D motions combining translations and rotations. Moreover, the pre-training scenario, using simulation training data sets, ensures prediction accuracies within the +/- 20% absolute error surfaces, profiling approximately normal distributions centered at approximately null error. These are impacting results in the scope of vibrational electromagnetic generation, holding potential to be extended to innovative self-adaptive electromagnetic generators, including those with ability to absorb complex 6 DOF external mechanical excitations. Besides, it can support the implementation of high-performance AI modelling -> analytical modelling synergies, aiming to re-parameterize the high complex analytical models throughout the EMG operation, such that a superior controllability of the adaptive systems can be achieved.

The development of self-powering systems has been recognized as critical such that innovative stand-alone emerging technologies can operate sustainably from scavenged ambient energy. Electromagnetic generators (EMGs) using magnetic levitation architectures for mechanical vibration energy harvesting are a promising technology that can be tailored to specific needs and provide low-cost electric powering for both small-scale and large-scale devices. They also present non-complex design, with low maintenance requirements and can operate with stable performance for long periods of time. Despite these prominent features, their complex non-linear and hysteresis-based resonant characteristics makes performance optimization hard to achieve and still needs to be addressed as a function of the input excitation. Numerical and experimental results are here provided to demonstrate the effectiveness of a new concept of EMG that aims to dynamically adapt the coil-array architecture throughout its operation to ensure maximum harvested power and to optimize the transduction mechanism efficiency. The self-adaptive motion-driven levitation-based autonomously rearranges each coil independently as a function of the instantaneous time-varying characteristics of the levitating magnet (LM) position. The mechanism features two dynamic coil switching strategies: (i) on/off switching, by short circuiting, with transmission gate switches, the coils without influence on the electromotive force; and (ii) reversing polarity switching, to avoid the sum of electromotive forces cancels each other. Average output powers of 635 mW (up to ∼4.1 W of peak power) were obtained with only the 4-centre (out of 14) permanently active coils, while only 292 mW (up to 833 mW of peak power) were achieved with the 14-coils permanently connected under optimal load conditions and harmonic translational input excitations with 15 Hz frequency and 20 mm amplitude. However, the adaptive generator was able to provide an impressive average power output of 3 W under the same conditions. Up to 14-fold larger output average power and 5.5-fold larger electric efficiency demonstrate the potential of the proposed coil switching self-adaptation system for enhancing the total energy conversion from general widespread mechanical vibrations.

Problem Therapeutic planning strategies have been developed to enhance the effectiveness of cancer drugs. Nevertheless, their performance is highly limited by the inefficient biological representativeness of predictive tumor growth models, which hinders their translation to clinical practice. Objective This study proposes a disruptive approach to oncology based on nature-inspired control using realistic Black Hole physical laws, in which tumor masses are trapped to experience attraction dynamics on their path to complete remission or to become a chronic disease. This control method is designed to operate independently of individual patient idiosyncrasies, including high tumor heterogeneities and highly uncertain tumor dynamics, making it a promising avenue for advancing beyond the limitations of the traditional survival probabilistic paradigm. Design Here, we provide a multifaceted study of chemotherapy therapeutic planning that includes: (1) the design of a pioneering controller algorithm based on physical laws found in the Black Holes; (2) investigation of the ability of this controller algorithm to ensure stable equilibrium treatments; and (3) simulation tests concerning tumor volume dynamics using drugs with significantly different pharmacokinetics (Cyclophosphamide and Atezolizumab), tumor volumes (200 mm3 and 12 732 mm3) and modeling characterizations (Gompertzian and Logistic tumor growth models). Results Our results highlight the ability of this new astrophysical-inspired control algorithm to perform effective chemotherapy treatments for multiple tumor-treatment scenarios, including tumor resistance to chemotherapy, clinical scenarios modelled by time-dependent parameters, and highly uncertain tumor dynamics. Conclusions Our findings provide strong evidence that cancer therapy inspired by phenomena found in black holes can emerge as a disruptive paradigm. This opens new high-impacting research directions, exploring synergies between astrophysical-inspired control algorithms and Artificial Intelligence applied to advanced personalized cancer therapeutics.

Self-powered electronic devices have been widely sought after in the last few years demanding efficient harvesting of locally available forms of energy. Electromagnetic generators are suitable contenders for powering both small-scale and large-scale devices due to their widespread availability and customizability. New promising magnet levitation architectures for mechanical vibration energy harvesting offer low production and maintenance costs, as well as a wide array of designs. They also exhibit complex non-linear and hysteretic resonant behaviors. Nonetheless, their performance is typically optimized towards external excitations with very specific characteristics. In this study, we theoretically and experimentally prove the concept of an instrumented self-adaptive levitation generator with on/off coil switching employing an accelerometer, transmission gate switches and a processing system. This adaptable system is able to periodically turn off coils not contributing to the generated electromotive forces for certain frequencies and amplitudes of the input excitations. Taking the power consumption of instrumentation into account, power gains up to asymptotic to 26% were achieved for harmonic inputs with randomly time changing frequencies and amplitudes. Using a prototype generator with 140.7 cm(3), output average powers of up to 1.79 W (i.e., 12.7 kW/m(3)) were extracted for optimal electrical loads under non-linear resonant conditions. Significant increases in electric power efficiencies were achieved as well. These promising results should pave the way towards intelligent self-adapting energy generators.

Lead-free multiferroic 3-0 type particulate composites with a composition (1-x)(Ba0.85Ca0.15Zr0.1Ti0.9O3) - x(Ni0.7Zn0.3Fe2O4) [(1-x)BCZT - xNZFO with 0 <= x <= 100 at%] were prepared using solid state reaction method. Structural and microstructural analysis using XRD, FESEM and Raman techniques confirmed the phase formation of the ferroelectric (BCZT) and magnetostrictive (NZFO) phases without any detectable presence of impurity phases. Rietveld refinement of the XRD data revealed a tetragonal (P4mm) and a cubic structure (Fd (3) over barm) for the BCZT and NZFO phases, respectively. Elemental compositions of the constituent phases were assessed by EDS and XPS analyses. Electrical, magnetic, and magnetoelectric (ME) measurements were performed. The composites exhibit typical well-saturated magnetic hysteresis (M-H) loops at room temperature, having very low coercive field (H-C) values, indicating their soft ferromagnetic behavior. Various parameters extracted from the M-H curves including H-C, magneto-crystalline anisotropy, squareness, and magnetization were found to depend on x. Frequency dependence of capacitance and admittance exhibited a resonance behavior corresponding to the radial mode of the electromechanical resonance (EMR). ME coefficients were studied in both longitudinal (alpha(E33)) and transverse (alpha(E31)) modes. The highest coupling coefficients, alpha(E31) similar to 14.5 mV/Oe.cm and alpha(E33) similar to 13 mV/Oe.cm were obtained for composite with 50 at% NZF at off-resonance frequency of 1 kHz. At the EMR frequency of 314 kHz, the alpha(E31) value in 0.5BCZT-0.5NZFO composite enhanced enormously to similar to 5.5 V/Oe.cm. The studies conclude that x = 0.5 is an optimum atomic fraction of NZFO in the particulate composite for maximum ME coupling.

Along with piezoelectric nanogenerators, triboelectric nanogenerators (TENGs) collecting energy from mechanical vibrations proved to be simple, low-cost, and efficient sources of electricity for various applications. In view of possible biomedical applications, the search for TENGs made of biomolecular and biocompatible materials is demanding. Diphenylalanine (FF) microstructures are promising for these applications due to their unique characteristics and ability to form various morphologies (microribbons, spherical vesicles, fibrils, micro- and nanotubes, nanorods, etc.). In this work, we developed a contact-separate mode TENG based on arrays of oriented FF microbelts deposited by dip-coating technique and studied their performance under various temperature treatments. We show that these TENGs outperform piezoelectric nanogenerators based on FF microbelts in terms of short-circuit current (ISC), open-circuit voltage (VOC), and output power. It was found that bound water captured in FF nanochannels mainly affects VOC, whereas mobile water increases ISC. We also found that the cyclization of FF molecules increases the performance of TENG likely due to an increase in surface energy and surface flattening.

Electromagnetic generators are widely used to power both small-scale and large-scale devices. They are suitable to operate as self-powering technologies, allowing customizable upscaling and downscaling, ensuring low production and maintenance costs, and even able to integrate into hybrid solutions. As their architectures are well-suited to power a broad range of multifunctional devices, their performance optimization is a research topic of utmost importance. Their performance, strongly dependent on the frequency and amplitude of mechanical excitations and hysteretic behaviors, still needs to be improved. In this paper, a theoretical and experimental study is provided to demonstrate the effectiveness of a new concept of self-adaptive electromagnetic generator. An instrumented generator using a magnetic levitation architecture was implemented using a stepper motor, an accelerometer and a processing system. Self-adaptability was realized by changing the generator's effective length and resonance frequency as a function of the mechanical excitation characteristics. Considering the power consumption of instrumentation, output power gains around 30% were achieved under conditions of harmonic inputs with time changing frequencies and amplitudes. These are very promising results that highlight the potential of self-adaptive energy harvesting technologies for opening new research directions towards the emerging of a new line of highly sophisticated autonomous generators.

Motion-driven electromagnetic-triboelectric energy generators (E-TENGs) hold a great potential to provide higher voltages, higher currents and wider operating bandwidths than both electromagnetic and triboelectric generators standing alone. Therefore, they are promising solutions to autonomously supply a broad range of highly sophisticated devices. This paper provides a thorough review focused on major recent breakthroughs in the area of electromagnetic-triboelectric vibrational energy harvesting. A detailed analysis was conducted on various architectures including rotational, pendulum, linear, sliding, cantilever, flexible blade, multidimensional and magnetoelectric, and the following hybrid technologies. They enable highly efficient ways to harvest electric energy from many forms of vibrational, rotational, biomechanical, wave, wind and thermal sources, among others. Open-circuit voltages up to 75 V, short-circuit currents up to 60 mA and instantaneous power up to 144 mW were already achieved by these nanogenerators. Their transduction mechanisms, including proposed models to make intelligible the involved physical phenomena, are also overviewed here. A comprehensive analysis was performed to compare their respective construction designs, external excitations and electric outputs. The results highlight the potential of hybrid E-TENGs to convert unused mechanical motion into electric energy for both large- and small-scale applications. Finally, this paper proposes future research directions toward optimization of energy conversion efficiency, power management, durability and stability, packaging, energy storage, operation input, research of transduction mechanisms, quantitative standardization, system integration, miniaturization and multi-energy hybrid cells.

With the recent thriving of low-power electronic microdevices and sensors, the development of components capable of scavenging environmental energy has become imperative. In this article, we studied bidomain congruent LiNbO3 (LN) single crystals combined with magnetic materials for dual, mechanical, and magnetic energy harvesting applications. A simple magneto-mechano-electric composite cantilever, with a trilayered long-bar bidomain LN/spring-steel/metglas structure and a large tip proof permanent magnet, was fabricated. Its vibration and magnetic energy harvesting capabilities were tested while trying to optimize its resonant characteristics, load impedance, and tip proof mass. The vibration measurements yielded a peak open-circuit voltage of 2.42 kV/g, a short-circuit current of [Formula: see text]/g, and an average power of up to 35.6 mW/g2, corresponding to a power density of 6.9 mW/(cm [Formula: see text]), at a low resonance frequency of 29.22 Hz and with an optimal load of 40 [Formula: see text]. The magnetic response revealed a resonant peak open-circuit voltage of 90.9 V/Oe and an average power of up to [Formula: see text]/Oe2, corresponding to a relatively large magnetoelectric coefficient of 1.82 kV/(cm · Oe) and a power density of [Formula: see text]/(cm [Formula: see text]). We thus developed a system that is, in principle, able to scavenge electrical power simultaneously from low-level ambient mechanical and magnetic sources to feed low-power electronic devices.

This study reports the creation of a highly sensitive, low-frequency magnetic field sensor based on a composite multiferroic consisting of a bidomain lithium niobate/metglas laminate shaped in form of a tuning fork. An efficient suppression of acoustic and thermal noises in the measurements of AC magnetic fields has been achieved. As a piezoelectric component we used a y + 128 degrees-cut lithium niobate single crystal. A metglas foil (serving as a magnetostrictive component) was antisymmetrically bonded to each fine of the tuning fork. The sensor demonstrated a 6.7 times increase of the sensitivity to magnetic fields as compared to a single-plate magnetoelectric (ME) sensor: the magnetic field detection limit was enhanced from 20 pT to 3 pT at a frequency of ca. 318 Hz, without any additional shielding from external noises. The advantages of the ME sensors based on bidomain lithium niobate over those based on PZT or PMN-PT are a much higher thermal stability, anhysteretic piezoelectric effect, large resistance to creep, lead-free nature and simple and cheap fabrication process. Ultimately, the tuning-fork ME sensors based on bidomain lithium niobate single crystals might be used in low frequency, ultra-sensitive, cheap and high-temperature magnetic field sensors for biomedical or space 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 [Formula: see text]) 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.

We present an investigation into the magnetic sensing performance of magnetoelectric bilayered metglas/bidomain LiNbO3 long thin bars operating in a cantilever or free vibrating regime and under quasi-static and low-frequency resonant conditions. Bidomain single crystals of Y + 128 degrees-cut LiNbO3 were engineered by an improved diffusion annealing technique with a polarization macrodomain structure of the 'head-to-head' and 'tail-to-tail' type. Long composite bars with lengths of 30, 40 and 45 mm, as well as with and without attached small tip proof masses, were studied. ME coefficients as large as 550 V (cm.Oe)(-1), corresponding to a conversion ratio of 27.5 V Oe(-1), were obtained under resonance conditions at frequencies of the order of 100 Hz in magnetic bias fields as low as 2 Oe. Equivalent magnetic noise spectral densities down to 120 pT Hz(-1/2 )at 10 Hz and to 68 pT Hz(-1/2) at a resonance frequency as low as 81 Hz were obtained for the 45mm long cantilever bar with a tip proof mass of 1.2g. In the same composite without any added mass the magnetic noise was shown to be as low as 37 pT Hz(-1/2) at a resonance frequency of 244 Hz and 1.2 pT Hz(-1/2) at 1335 Hz in a fixed cantilever and free vibrating regimes, respectively. A simple unidimensional dynamic model predicted the possibility to drop the low-frequency magnetic noise by more than one order of magnitude in case all the extrinsic noise sources are suppressed, especially those related to external vibrations, and the thickness ratio of the magnetic-to-piezoelectric phases is optimized. Thus, we have shown that such systems might find use in simple and sensitive room-temperature low-frequency magnetic sensors, e.g. for biomedical applications.

We investigated the magnetoelectric properties of a new laminate composite material based on y + 140°-cut congruent lithium niobate piezoelectric plates with an antiparallel polarized “head-to-head” bidomain structure and metglas used as a magnetostrictive layer. A series of bidomain lithium niobate crystals were prepared by annealing under conditions of Li2O outdiffusion from LiNbO3 with a resultant growth of an inversion domain. The measured quasi-static magnetoelectric coupling coefficient achieved |αE31| = 1.9 V·(cm Oe)−1. At a bending resonance frequency of 6862 Hz, we found a giant |αE31| value up to 1704 V·(cm Oe)−1. Furthermore, the equivalent magnetic noise spectral density of the investigated composite material was only 92 fT/Hz1/2, a record value for such a low operation frequency. The magnetic-field detection limit of the laminated composite was found to be as low as 200 fT in direct measurements without any additional shielding from external noises.

The anisotropic direct magnetoelectric (ME) properties of bilayered composites comprising magnetostrictive metglas foils and single-crystalline piezoelectric bidomain plates of 127°Y-cut LiNbO3 (LNO) have been studied theoretically and experimentally. The LNO plates possessed an engineered ferroelectric macrobidomain structure with opposite spontaneous polarization vectors. Impedance, ME effect, and equivalent magnetic noise density (EMND) measurements have been performed under quasi-static and resonant conditions. Whereas the quasi-static ME effect was only two times stronger in the bidomain samples compared to their unidomain and bonded bimorph counterparts, in the bending resonance mode, the effect was up to one order of magnitude stronger: ME coefficients of up to 578 V/( [Formula: see text]) were obtained at ca. 30 kHz under resonance using 0.5-mm-thick crystals. EMND measurements yielded values down to 153 pT/Hz 1/2 at 1 kHz and 524 fT/Hz 1/2 under resonant conditions. A further optimization of the fabrication techniques, laminate geometry, and detection circuit is expected to allow reducing these values down to at least 10 pT/Hz 1/2 and 250 fT/Hz 1/2 , respectively, and the resonance frequency by at least two orders of magnitude. Such systems may thus find use in simple and sensitive, passive and stable, low frequency and high-temperature vector magnetic field sensors.

This chapter presents a theoretical basis of the anisotropic magnetoelectric (ME) effect in tri-layers of metglas and piezoelectric (PE) single crystals. The properties of various common PE and magnetostrictive substances are discussed, and arguments for the choice of the most appropriate materials are made. A linear description of the ME effects in terms of electric, magnetic and elastic material fields and material constants is presented. An averaging quasi-static method is used to illustrate the relation between the material constants, their anisotropy and the transversal direct ME voltage and charge coefficients. Subsequently, the aforementioned model is employed in the calculation of the maximum expected direct ME voltage coefficient for a series of tri-layered Metglas/Piezocrystal/Metglas composites as a function of the PE crystal orientation. The ME effects are shown to be strongly dependent on the crystal orientation, which supports the possibility of inducing large ME voltage coefficients in composites comprising lead-free PE single crystals such as LiNbO3, LiTaO3, alpha-GaPO4, a-quartz, langatate and langasite through the optimization of the crystal orientation.