Magnetoelastic Research Articles

Magnetoelastic Immunosensor for the Rapid Detection of SARS-CoV-2 in Bioaerosols.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a protein-coated, single-stranded RNA virus that parasitizes and infects primates, including humans. The current detection methods are mainly carried out using humans as a medium, such as a chest computed tomography (CT) examination, nucleic acid detection, antibody detection, and antigen detection. In addition, SARS-CoV-2 in bioaerosols is an important way of transmission and infection, which has attracted wide attention. In this paper, we simulate a sampling system of SARS-CoV-2 in bioaerosols and detect SARS-CoV-2 in bioaerosols by means of a magnetoelastic (ME) sensing device based on an Android intelligent terminal, which can directly detect SARS-CoV-2 in bioaerosols in a certain unit environment. This approach aims to achieve early detection and prevention. The experimental results show that the sampling system can successfully collect SARS-CoV-2 in bioaerosols. In the linear range of 5-20 ng/mL, the ME sensing detection system results closely match those of the calibration instrument (VNA), with goodness-of-fit values of 0.997 and 0.995, respectively. This work demonstrates that the ME sensing detection system proposed is stable, highly specific, real-time, rapid, and has certain reference values and feasibility.

Novel flexible magnetoelastic biosensor based on PDMS/FeSiB/QD composite film for the detection of African swine fever virus P72 protein.

African swine fever (ASF) is a highly contagious and severe hemorrhagic disease caused by the African swine fever virus (ASFV). The continuous spread of ASFV affects the safety of the global meat supply; therefore, the establishment of sensitive and specific detection methods for ASFV has become an important hot spot in food safety. Herein, we developed a flexible magnetoelastic (ME) biosensor based on PDMS/FeSiB/QDs composite films for the detection of ASFV P72 protein. Based on the high luminescence performance of CsPbBr3 quantum dots and the excellent magnetoelastic effect of FeSiB, flexible ME biosensors convert stress signals generated by antibody-antigen-specific binding into optical and electromagnetic signals. The nanostructures covalently linked by quantum dots and PDMS provide biomodification sites for ASFV P72 antibodies, simplifying the functionalization modification process compared to the case of conventional biosensors. The deformation of the PDMS film is amplified, and the conversion of surface stress signals to electrical signals is enhanced by exposing the biosensor to a uniform magnetic field. The experimental results proved that the flexible ME biosensor has a wide linear range of 10 ng mL-1-100 μg mL-1, and the detection limit is as low as 0.079 ng mL-1. Moreover, the flexible ME biosensor also shows good stability, sensitivity and specificity, confirming the potential for early disease screening.

A novel magnetoelastic biosensor consisting of carbon quantum dots/nitrocellulose membranes and NiFe2O4/ polylactic acid based on 3D printing for α2-macroglobulin detection

α2-macroglobulin (α2-M) have crucial clinical significance as a potent biomarker for diabetes nephropathy (DN). There is an increasing demand for rapid detection of α2-M. Herein, a magnetoelastic (ME) biosensor with a layered composite structure is developed for α2-M detection. Based on 3D printing, the basal layer of the biosensor is prepared as a grid structure fabricated by polylactic acid (PLA) doped with NiFe2O4. The conductivity of the biosensor was improved significantly due to the addition of multi-walled carbon nanotubes (MWCNTs). The biological site for capturing α2-M antigen was provided by the carbon quantum dots (CDs) coupled with anti-α-2M (anti-α2-M@CDs) in the nitrocellulose filter (NC) membrane. Meanwhile, the distribution of antibodies on the biosensor surface can be observed more directly due to the fluorescence characteristics of CDs. The biosensor in this work can realize multi-pattern recognition of fluorescent signal and electromagnetic signal. The results show that the limit of detection (LOD) was 0.506 ng/mL in the linear range from 10 ng/mL to 100 µg/mL and the linear equation of fitting curve is: y = 0.21 x - 0.15. The ME biosensors with a simple preparation method have advantages of high sensitivity, good stability and low LOD, showing the great potential for α2-M detection.

A novel flexible magnetoelastic biosensor with “sandwich” structure based on transferrin encapsulated gold nanoclusters for 5-hydroxytryptamine detection

5-hydroxytryptamine (5-HT), a mono-amine neurotransmitter, plays an important role in regulating the dynamics of neural circuits in the central nervous system and enteric nervous system. Accurate and sensitive monitoring of 5-HT will provide critical information for diagnosing many psychiatric and neurological disorders. However, there are no superior clinical assays for the detection of 5-HT, and existing methods of gas chromatographs and mass spectrometers are expensive, limiting portable and real-time monitoring as diagnostic approaches in the clinical setting. Therefore, a convenient, rapid, and low-cost method for the detection of 5-HT is still in demand in current clinical medicine. Herein, a novel flexible magnetoelastic (ME) biosensor with “sandwich” structure is proposed for 5-HT detection based on transferrin encapsulated gold nanoclusters (Tf-AuNCs). Combined with the magnetoelastic effect of CoFe2O4, the excellent conductivity of silver nanowires (AgNWs), and the fluorescence properties of Tf-AuNCs, the ME biosensor designed in this paper can achieve multi-signal recognition. Rapid and sensitive detection of 5-HT is achieved by a biosensing process that converts surface stress signal into magnetoelectric signals. The biosensor is capable of detecting 5-HT with different concentrations in a linear range of 10 ng/mL-100 μg/mL (R2 = 0.97119) with a lower detection limit (LOD) of 0.33 ng/mL. The accurate measurement results of 5-HT in human serum of clinical samples demonstrated the feasibility of the biosensor for 5-HT detection. This flexible ME biosensor was prepared in a simple process with great specificity and stability, providing a portable analytical device for the rapid and sensitive detection of 5-HT, which is of great significance for the clinical research of various neurological diseases.

Role of extrinsic factors on magnetoelastic resonance biosensors sensitivity

Magnetoelastic (ME) resonance devices are attractive for application as biosensors in health-related areas as they allow contactless detection of pathogenic agents with high sensitivity. After functionalization, they offer valuable diagnostic options that promote efficient capture of mass on the sensor surface through biological interactions. ME sensors are also sensitive to external factors such as temperature, magnetic fields, and variations in mass that can arise from processes unrelated to biological interactions, including corrosion and salt crystallization. This article evaluates extrinsic factors that affect the response of ME resonance sensors for diagnostic applications. In particular, the influence of heat treatments, operation temperature, applied DC magnetic field bias, and corrosive environment were studied. The control of all these factors is crucial for the design, fabrication, and functionalization of ME resonance biosensors and for the development of measuring instrumentation and effective measurement protocols. This work established maximum operating temperature and bias field variations to keep the sensor sensitivity. Heat treatment of the sensors before and after coating improved the signal-to-noise ratio and corrosion resistance. Further improvement in corrosion resistance was provided by cathodic protection, which has been proven beneficial for applications of ME resonance sensors in aqueous fluids.

User-friendly, signal-enhanced planar spiral coil-based magnetoelastic biosensor combined with humidity-resistant phages for simultaneous detection of Salmonella Typhimurium and Escherichia coli O157:H7 on fresh produce

A user-friendly, signal-enhanced magnetoelastic (ME) biosensor was newly constructed, consisting of three sensors, a movable pencil-type planar spiral coil, and a set of hand-held signal amplifiers. It was combined with humidity-resistant, wild-type phages instead of humidity-susceptible E2 phage to simultaneously detect Salmonella Typhimurium (ST) and Escherichia coli O157:H7 (EC) on the surface of an apple. The set of hand-held signal amplifiers, four times smaller than those in the planar spiral coil-based ME biosensor, was constructed with an optimal DC magnetic field strength of 76 G. These optimized hand-held signal amplifiers enhanced the signal amplitude of the sensor by up to 1.5 times, enabling the distinction of individual peaks from three sensors. Both phage-immobilized sensors detected each target specifically under ambient humidity without the need for a bulky humidifier. The optimized exposure time for phage binding with each target on fresh produce was 16 min, almost twice as fast as the rectangular solenoid coil-based ME biosensor. The signal-enhanced ME biosensor detected its target bacteria from a mixture of ST and EC inoculated on an apple simultaneously with an enhanced detection limit of 1.7 ± 0.4 log CFU/25 mm2 for ST and 1.6 ± 0.3 log CFU/25 mm2 for EC. Notably, the detection limit and sensitivity did not show significant differences between each single analyte and bacterial mixture, indicating no interference with another coexisting pathogens. Our findings highlight the signal-enhanced ME biosensor as a rapid, efficient, specific, and user-friendly method for the simultaneous detection of fresh produce-borne pathogens.

Equivalent Circuit Models for Magnetoelastic Resonance Sensors With Various Surface Loadings

Sensors based on the magnetoelastic (ME) effect have been developed for various applications, such as food safety, immunoassays, and health monitoring. A major obstacle to the widespread adoption of ME sensors is the poor understanding of the electrical impedances that constitute the system and how these impedances are influenced by surface loadings. Here, we derive a lumped-element model to approximately predict the near-resonance electrical behavior of an ME sensor simultaneously loaded with a mass layer and a semi-infinite Newtonian liquid. For more extensive applicability, a hybrid model, combining a modified Butterworth–Van Dyke (mBVD) model and a transmission line model, is derived for the first time to predict the response of the ME sensor under various surface conditions, including rigid solids, fluids, viscoelastic media, or any combinations thereof. The theoretical models are experimentally verified for accuracy and used to quantitatively analyze the mass, viscosity, and modulus of loadings by extracting the electrical parameters. This modeling work is crucial for the development of ME sensors in various applications and for providing insights into the physical mechanisms of advanced devices.

Portable, High-Sensitive, and Metglas Alloy 2826 MB-Based Magnetoelastic Biosensor to Detect the Osteoarthritis Marker MMP-3

Osteoarthritis (OA) is one of the most common joint disorders affecting human health. Early detection of OA is essential for effective treatment of the disease. There is a growing demand of techniques for highly sensitive detection of trace OA markers. Here, the magnetoelastic (ME) biosensor based on Metglas alloy 2826 MB is presented to detect matrix metalloproteinase-3 (MMP-3) of the OA biomarker, through the measurement of resonant frequency changes with excellent magnetostrictive effects. The detection system consists of an ME chip immobilized with MMP-3 antibody and an electromagnetic coil. Since the ME biosensor is ultrasensitive to mass changes, the frequency shift caused by mass changes induced by antibody–antigen-specific binding can be used to reflect the amount of MMP-3. The ME biosensor has been applied to detect the actual joint fluid sample of OA patients, demonstrating its feasibility. The results show that this assay has a linear response to the MMP-3 concentrations ranging from 30.7 to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2000\,\,{\mathrm {ng}} \cdot\,{\mathrm {mL}}^{-}1$ </tex-math></inline-formula> with a detection limit of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$30.7\,\,{\mathrm {ng}} \cdot\,{\mathrm {mL}}^{-}1$ </tex-math></inline-formula> , covering the range of clinical tests required for the diagnosis of OA. The ME biosensor provides a novel and viable method for the diagnosis of early OA.

A Novel Magnetoelastic Biosensor With Flexible TbDyFe Film as Sensing Materials for Osteoarthritis Marker MMP-3 Detection

A new design of flexible magnetoelastic (ME) biosensor based on TbDyFe/polystyrene-poly (ethylene-butylene)-polystyrene block copolymer (SEBS) film for the osteoarthritis (OA) marker matrix metalloproteinase 3 (MMP-3) detection is presented. This article studied a novel flexible ME film to replace the traditional rigid substrate for biosensors. The magnetostrictive material of TbDyFe was mixed homogeneously with paraffin solution to fabricate TbDyFe fluid, which was reacted at high temperature with SEBS in a certain ratio to prepare the film. TbDyFe/SEBS films were used as substrates for the immobilization of MMP-3 antibodies. Specific binding of antibodies to MMP-3 antigens generated compressive stress on the substrate surface, which in turn led to changes in magnetic permeability and impedance. To improve the sensitivity of the biosensor, the TbDyFe doping concentration was optimized and the magnetic response performance of the TbDyFe/SEBS composite film was measured. The results show that this assay is capable of detecting concentrations of MMP-3 between 0.76 and 10000 ng <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot $ </tex-math></inline-formula> mL−1 with a detection limit of 0.76 ng <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot $ </tex-math></inline-formula> mL−1, covering the range of clinical tests required for the diagnosis of OA. This novel flexible ME biosensor provides a viable method for the diagnosis and monitoring of OA.

Surface Functionalization, Bioanalysis, and Applications: Progress of New Magnetoelastic Biosensors

Magnetoelastic (ME) biosensors are portable, nontoxic, inexpensive, compatible with wireless networks, and have high sensitivity, accuracy, and specificity toward the target element. Thus, they have attracted considerable attention in application of biological identification, chemical detection, and medical diagnosis, as well as in many academic achievements in the field of sensor research. Herein, the recent progress of ME biosensors, including surface functionalization, bioanalysis, and its applications is critically reviewed. The remaining scientific and technological challenges related to the development of novel ME biosensors with new materials and structures in this field are elaborated, too. This review not only can provide a guideline for researchers in future development of ME biosensors, but also further improves their detection performance and expand the scope of their applications.

Magnetoelastic Materials for Monitoring and Controlling Cells and Tissues

Advances in cell and tissue therapies are slow to be implemented in the clinic due to the limited standardization of safety and quality control techniques. Current approaches for monitoring cell and tissue manufacturing processes are time and labor intensive, costly, and lack commercial scalability. One method to improving in vitro manufacturing processes includes utilizing the coupled magnetic and mechanical properties of magnetoelastic (ME) materials as passive and wireless sensors and actuators. Specifically, ME materials can be used in quantifying cell adhesion, detecting contamination, measuring biomarkers, providing biomechanical stimulus, and enabling cell detachment in bioreactors. This review outlines critical design considerations for ME systems and summarizes recent developments in utilizing ME materials for sensing and actuation in cell and tissue engineering.

Magnetoelastic Immunosensor via Antibody Immobilization for the Specific Detection of Lysozymes.

Lysozymes in human urine have crucial clinical significance as an indicator of renal tubular and glomerular diseases. Most lysozyme detection methods rely on the enzyme-linked immunosorbent assay (ELISA), which is usually a tedious procedure. Meanwhile, aptamer sensors and fluorescence-based techniques for lysozyme detection have emerged in recent studies. However, these methods are time-consuming and highly complex in operation, and some even require exorbitant reagents and instruments, which restricts real-time clinical monitoring as diagnostic approaches. Therefore, a rapid and low-cost lysozyme detection method with facile preparation is still in demand for modern precision medicine. Herein, we propose a magnetoelastic (ME) immunosensor for lysozyme detection by detecting changes in resonance frequency under a magnetostrictive effect. The detection system is composed of a magnetoelastic chip with an immobilized lysozyme antibody, a solenoid coil, and a vector network analyzer. Since the ME sensor is ultrasensitive to mass change, the frequency offset caused by mass change can be utilized to detect the content of lysozyme. The immunosensor is evaluated to possess superior sensitivity of 138 Hz/μg mL-1 in terms of the resonance frequency shift (RFS). In addition, our sensor displays an outstanding performance in specificity experiments and shows a relatively lower detection limit (1.26 ng/mL) than other conventional lysozyme detection methods (such as ELISA, chemiluminescence assay, fluorescence, and aptamer biosensors).

A magnetoelastic bone fixation device for controlled mechanical stimulation at femoral fractures in rodents

Studies have shown that mechanical stimulations can provide anabolic bone formation and counteract conditions such as osteoporosis in intact bones, as well as promote healing of bone fractures. However, many of these studies are based on external mechanical loading platforms or bulky wearable force loading systems, which are inconvenient and impractical in clinical settings especially for the treatment of bone injuries. To overcome this limitation, a bone fixation device was developed to provide localized mechanical strains across a bone fracture site. The fixation device, designed for a rodent’s femoral fracture (critical-size segmental defect), is consisted of a magnetoelastic (ME) actuator that changes its physical dimension when exposed to magnetic fields. The strain produced by the ME actuator is transferred to the bone fixation device, which acts directly on the bone-implant interface to produce a highly focused and localized mechanical loading. The actuation generated by the fixation device was evaluated, and results show the device was able to provide up to 150 με at 30 Hz. Mechanical characterization of the fixation device showed its off-axis compressive stiffness was higher than 160 N mm−1, which was comparable to existing fixation devices used for the same rodent’s femoral fracture model. Furthermore, the fixation device was implanted in rodent subjects for 8 weeks to validate its safety and biocompatibility in vivo. Results indicate the device is biocompatible, showing no adverse impact on bone regeneration.

Magnetoelastic sensors for real-time tracking of cell growth.

Magnetoelastic (ME) sensors, which can be remotely activated via magnetic fields, are an excellent choice for wireless monitoring of biological parameters due to their ability to be scaled into different sizes and have their surface functionalized for chemical or biological sensing. In this study, we present the application of a commercially available ME material (Metglas 2826 MB) to develop a sensor system that can monitor the attachment of anchorage-dependent mammalian cells in two-dimensionalin vitro cell cultures. Results obtained with the developed sensors and detection system correlated with microscopic image analysis of cell quantification, which showed a linear relationship between the sensor response and attached fibroblast cells on the sensor surface. It was also revealed that the developed ME sensor system is capable of providing temporal profiles of cell growth corresponding to different stages of cell attachment and proliferation in real-time.

3D Phage-based biomolecular filter for effective high throughput capture of Salmonella Typhimurium in liquid streams

Foodborne illnesses caused by pathogens on fresh produce remain one of the most critical food safety problems the world faces. The recalls of pasta salad in 2018 and pre-cut melons in 2019 imply current methods in identifying the source of pathogens and outbreak prevention are inappropriate and time consuming. In this article, a new technology, called the 3D phage-based biomolecular filter, was developed to simultaneously capture and concentrate foodborne pathogens from large volumes of liquid streams (food liquid or wash water streams). The 3D phage-based filter consisted of phage-immobilized magnetoelastic (ME) filter elements, a filter pipe system, and a uniform magnetic field to fix and align the ME filter elements in the 3D filter column. The closely packed ME filter elements display a 3D layered structure which allows for enhanced surface interaction of the immobilized bacteriophage with specific pathogens in the passing liquid streams. As a result, a pathogen capture rate of more than 90% was achieved at a high flow rate of 3 mm/s with 20,000 ME filter elements. The capability of the 3D phage-based filter to capture pathogens in liquid streams at different filter element packing densities was further validated by experiments, finite element analysis and theoretical calculations. The capture rate increases significantly with larger numbers of ME filter elements placed in the testing pipe, and the turbulence flow induced by the 3D stacking of ME filter elements can further improve the capture efficiency. This technology enables rapid capture and analysis of large volume of water in processing fresh fruit and vegetables for the presence of small quantities of pathogens, which will ultimately benefit producers, the food industry, and society with improved food safety and production efficiency.

A Novel NiFe2O4/Paper-Based Magnetoelastic Biosensor to Detect Human Serum Albumin.

For the first time, a novel NiFe2O4/paper-based magnetoelastic (ME) biosensor was developed for rapid, sensitive, and portable detection of human serum albumin (HSA). Due to the uniquely magnetoelastic effect of NiFe2O4 nanoparticles and the excellent mechanical properties of the paper, the paper-based ME biosensor transforms the surface stress signal induced by the specific binding of HSA and antibody modified on the paper into the electromagnetic signal. The accumulated binding complex generates a compressive stress on the biosensor surface, resulting in a decrease in the biosensor’s static magnetic permeability, which correlates to the HSA concentrations. To improve the sensitivity of the biosensor, the concentration of NiFe2O4 nanofluid and the impregnated numbers of the NiFe2O4 nanofluid-impregnated papers were optimized. The experimental results demonstrated that the biosensor exhibited a linear response to HSA concentrations ranging from 10 μg∙mL−1 to 200 μg∙mL−1, with a detection limit of 0.43 μg∙mL−1, which is significantly lower than the minimal diagnosis limit of microalbuminuria. The NiFe2O4/paper-based ME biosensor is easy to fabricate, and allows the rapid, highly-sensitive, and selective detection of HSA, providing a valuable analytical device for early monitoring and clinical diagnosis of microalbuminuria and nephropathy. This study shows the successful integration of the paper-based biosensor and the ME sensing analytical method will be a highly-sensitive, easy-to-use, disposable, and portable alternative for point-of-care monitoring.

Exploring the feasibility of Salmonella Typhimurium-specific phage as a novel bio-receptor.

The purpose of this study was aimed to isolate a Salmonella Typhimurium-specific phage (KFS-ST) from washing water in a poultry processing facility and to investigate the feasibility of the KFS-ST as a novel bio-receptor for the magnetoelastic (ME) biosensor method. KFS-ST against S. Typhimurium was isolated, propagated, and purified using a CsCl-gradient ultracentrifugation. Morphological characteristics of KFS-ST were analyzed using transmission electron microscopy (TEM). Its specificity and efficiency of plating analysis were conducted against 39 foodborne pathogens. The temperature and pH stabilities of KFS-ST were investigated by the exposure of the phage to various temperatures (−70°C–70°C) and pHs (1–12) for 1 h. A one-step growth curve analysis was performed to determine the eclipse time, latent time and burst size of phage. The storage stability of KFS-ST was studied by exposing KFS-ST to various storage temperatures (−70°C, −20°C, 4°C, and 22°C) for 12 weeks. KFS-ST was isolated and purified with a high concentration of (11.47 ± 0.25) Log PFU/mL. It had an icosahedral head (56.91 ± 2.90 nm) and a non-contractile tail (225.49 ± 2.67 nm), which was classified into the family of Siphoviridae in the order of Caudovirales. KFS-ST exhibited an excellent specificity against only S. Typhimurium and S. Enteritidis, which are considered two of the most problematic Salmonella strains in the meat and poultry. However, KFS-ST did not exhibit any specificity against six other Salmonella and 27 non-Salmonella strains. KFS-ST was stable at temperature of 4°C to 50°C and at pH of 4 to 12. The eclipse time, latent time, and burst size of KFS-ST were determined to be 10 min, 25 min and 26 PFU/ infected cell, respectively. KFS-ST was relatively stable during the 12-week storage period at all tested temperatures. Therefore, this study demonstrated the feasibility of KFS-ST as a novel bio-receptor for the detection of S. Typhimurium and S. Enteritidis in meat and poultry products using the ME biosensor method.

Core-Shell Magnetic Nanoparticles for Highly Sensitive Magnetoelastic Immunosensor.

A magnetoelastic (ME) biosensor for wireless detection of analytes in liquid is described. The ME biosensor was tested against human IgG in the range 0–20 μg∙mL−1. The sensing elements, anti-human IgG produced in goat, were immobilized on the surface of the sensor by using a recently introduced photochemical immobilization technique (PIT), whereas a new amplification protocol exploiting gold coated magnetic nanoparticles (core-shell nanoparticles) is demonstrated to significantly enhance the sensitivity. The gold nanoflowers grown on the magnetic core allowed us to tether anti-human IgG to the nanoparticles to exploit the sandwich detection scheme. The experimental results show that the 6 mm × 1 mm × 30 μm ME biosensor with an amplification protocol that uses magnetic nanoparticles has a limit of detection (LOD) lower than 1 nM, works well in water, and has a rapid response time of few minutes. Therefore, the ME biosensor is very promising for real-time wireless detection of pathogens in liquids and for real life diagnostic purpose.

Large Nonreciprocal Propagation of Surface Acoustic Waves in Epitaxial Ferromagnetic/Semiconductor Hybrid Structures

Non-reciprocal propagation of sound, that is, the different transmission of acoustic waves traveling along opposite directions, is a challenging requirement for the realization of devices like acoustic isolators and circulators. Here, we demonstrate the efficient non-reciprocal transmission of surface acoustic waves (SAWs) propagating along opposite directions of a GaAs substrate coated with an epitaxial Fe$_3$Si film. The non-reciprocity arises from the acoustic attenuation induced by the magneto-elastic (ME) interaction between the SAW strain field and spin waves in the ferromagnetic film, which depends on the SAW propagation direction and can be controlled via the amplitude and orientation of an external magnetic field. The acoustic transmission non-reciprocity, defined as the difference between the transmitted acoustic power for forward and backward propagation under ME resonance, reaches values of up to 20%, which are, to our knowledge, the largest non-reciprocity reported for SAWs traveling along a semiconducting piezoelectric substrate covered by a ferromagnetic film. The experimental results are well accounted for by a model for ME interaction, which also shows that non-reciprocity can be further enhanced by optimization of the sample design. These results make Fe$_3$Si/GaAs a promising platform for the realization of efficient non-reciprocal SAW devices.

Wave energy localization near the rough surfaces of piezoelectric waveguide. Near-surface inhomogeneities as a resonator or filter

Propagation of high-frequency electro-elastic normal wave signal in a composite waveguide is investigated. The roughnesses on a two surfaces of the piezoelectric waveguide are filled with an ideal conductor and ideal dielectric respectively. The both of the influence of surface roughness and the influence non-homogeneity of materials near the surfaces on the process of high frequency electro-elastic normal wave signal propagation, is discussed. The behaviors the frequency characteristics of wave in the composite waveguide at the propagation of normal wave signals numerically are investigated. The problem by the method of virtual cross sections and input of Magneto Elastic Layered System (MELS) hypotheses is solved. It is shown that in a case of not filled roughness of the piezoelectric layer surfaces, only two short wave modes are arise. The filling of the surface roughness with a dielectric or a conductor respectively, leads to the appearance of up to four such wave modes, depending at the wave signal length. The dispersion dependencies for all possible characteristic modes of shear electroelastic waves are given. It is shown that in a case of the propagation of slow waves, on certain wave lengths the silence frequency zones are arise.