Autonomous ferries offer a promising solution to challenges in public waterway transport, such as crew shortage and environmental impact. Safe navigation requires reliable sensor performance, particularly in adverse maritime conditions like fog, rain, and low visibility. This paper evaluates LiDAR, mmWave radar, and infrared/RGB cameras under real-world conditions aboard a medium-sized autonomous ferry prototype. A virtual test field in Unreal Engine 5 was used to assess sensor configurations and field trials validated performance in varying weather conditions. Results show LiDAR's range and density loss in fog and rain, the robustness of mmWave radar for long-range detection, and the benefit of pairing it with PTZ-mounted infrared cameras for improved tracking in low-visibility scenarios. We propose an optimized multi-sensor configuration combining these technologies to maximize perception accuracy. By linking simulation and experimental findings, this study provides actionable recommendations for weather-resilient perception systems and informs sensor fusion strategies for small to medium-sized autonomous vessels. Autonome F & auml;hren bieten eine vielversprechende L & ouml;sung f & uuml;r Herausforderungen im & ouml;ffentlichen Wasserverkehr, wie Personalengp & auml;sse und Umweltbelastung. F & uuml;r eine sichere Navigation ist eine zuverl & auml;ssige Sensorleistung entscheidend, insbesondere bei widrigen Bedingungen wie Nebel, Regen und eingeschr & auml;nkter Sicht. Diese Arbeit bewertet LiDAR, mmWave-Radar und Infrarot/RGB-Kameras unter realen Bedingungen an Bord eines mittelgro ss en autonomen F & auml;hrprototyps. Ein virtuelles Testfeld in Unreal Engine 5 diente zur Analyse verschiedener Sensorkonfigurationen; Praxistests validierten die Ergebnisse bei unterschiedlichen Wetterbedingungen. Die Ergebnisse zeigen Reichweitenverluste und eine reduzierte Punktdichte von LiDAR bei Nebel und Regen, die Robustheit von mmWave-Radar f & uuml;r die Langstreckenerkennung sowie den Vorteil der Kombination mit schwenkbaren Infrarotkameras (PTZ) f & uuml;r eine verbesserte Objektverfolgung bei schlechter Sicht. Auf Basis dieser Erkenntnisse stellen wir eine optimierte Multisensor-Konfiguration vor, die diese Technologien zur Maximierung der Wahrnehmungsgenauigkeit kombiniert. Durch die Verkn & uuml;pfung von Simulation und Experiment liefert die Studie konkrete Empfehlungen f & uuml;r wetterfeste Wahrnehmungssysteme und unterst & uuml;tzt die Entwicklung robuster Sensorfusionsstrategien f & uuml;r kleine und mittelgro ss e autonome Schiffe.

Magnetoelectric thin-film cantilevers consisting of strain-coupled magnetostrictive and piezoelectric layers are promising candidates for magnetic field measurements in biomedical applications. In this study, we investigate magnetoelectric cantilevers that are electrically excited and operated in a special mechanical mode with resonance frequencies above 500 kHz. In this particular mode, the cantilever bends in the short axis, forming a distinctive U-shape and exhibiting high-quality factors and a promising limit of detection of 70pT/Hz1/2 at 10 Hz. Despite this U mode, the sensors show a superimposed mechanical oscillation along the long axis. The induced local mechanical strain in the magnetostrictive layer results in magnetic domain activity. Due to this, the mechanical oscillation may cause additional magnetic noise, deteriorating the limit of detection of such sensors. We compare finite element method simulations with measurements of magnetoelectric cantilevers in order to understand the presence of oscillations. From this, we identify strategies for eliminating the external effects that affect sensor operation. Furthermore, we investigate the influence of different design parameters, in particular the cantilever length, material parameters and the type of clamping, on the amplitude of the undesired superimposed oscillations. We propose design guidelines to minimize the unwanted oscillations.

In this theoretical study, we explore the enhancement of sensing capabilities in surface acoustic wave (SAW)-based magnetic field sensors through the integration of engineered phononic crystals (PnCs). We particularly focus on amplifying the interaction between the SAW and magnetostrictive materials within the PnC structure. Through comprehensive simulations, we demonstrate the synchronization between the SAWs generated by IDTs and the resonant modes of PnCs, thereby leading to an enhancement in sensitivity. Furthermore, we investigate the ΔE effect, highlighting the sensor's responsiveness to changes in external magnetic fields, and quantify its magnetic sensitivity through observable changes in the SAW phase velocity leading to phase shifts at the end of the delay line. Notably, our approach yields a magnetic field sensitivity of approximately S~138 °mT for a delay line length of only 77 µm in homogeneous magnetic fields. Our findings underline the potential of PnCs to advance magnetic field sensing. This research offers insights into the integration of engineered materials for improved sensor performance, paving the way for more effective and accurate magnetic field detection solutions.

We investigate a coupled multiscale 3-D finite-element model consisting of an orthogonal array of thin-film cantilever magnetoelectric (ME) magnetic field sensors and a simplified human head model. Electric point dipole sources are placed inside the head to generate an electromagnetic field. This field propagates through the tissue layers and outside of the head, where it reaches the sensor array. The investigated sensors are based on a 300- $\mu \text{m}$ -thick silicon substrate layer of 26.25 mm length and 2.45 mm width, with a 20- $\mu \text{m}$ -thick aluminum nitride (AlN) layer and a 20- $\mu \text{m}$ -thick FeCoSiB layer as piezoelectric (PE) and magnetostrictive materials, respectively, located on opposite sides of the substrate. We position three sensors orthogonally to obtain a vector field sensor. The head model is based on the three-shell approach and consists of concentric spheres representing white matter, skull, and skin. All three layers are assigned specific conductivity and relative permittivity values from the literature, aiming to approximate the propagation of electromagnetic fields through different tissue types. We observe the propagation of an electric field generated by the dipole source and subsequent induction of a magnetic field inside the head structure, propagating outwards to the sensor array, where the generated voltage in the PE layer is evaluated for different ME sensor array and source positions and orientations. We show different behaviors of the sensors for a dipole source inside the head tissue versus a simple air environment, highlighting the benefits in accuracy and specificity of a combined head and sensor model with realistic material parameters.

Magnetomyography (MMG) with superconducting quantum interference devices (SQUIDs) enabled the measurement of very weak magnetic fields (femto to pico Tesla) generated from the human skeletal muscles during contraction. However, SQUIDs are bulky, costly, and require working in a temperature-controlled environment, limiting wide-spread clinical use. We introduce a low-profile magnetoelectric (ME) sensor with analog frontend circuitry that has sensitivity to measure pico-Tesla MMG signals at room temperature. It comprises magnetostrictive and piezoelectric materials, FeCoSiB/AlN. Accurate device modelling and simulation are presented to predict device fabrication process comprehensively using the finite element method (FEM) in COMSOL Multiphysics. The fabricated ME chip with its readout circuit was characterized under a dynamic geomagnetic field cancellation technique. The ME sensor experiment validate a very linear response with high sensitivities of up to 378 V/T driven at a resonance frequency of fres = 7.76 kHz. Measurements show the sensor limit of detections of down to 175 pT/√Hz at resonance, which is in the range of MMG signals. Such a small-scale sensor has the potential to monitor chronic movement disorders and improve the end-user acceptance of human–machine interfaces.

Magnetoelectric cantilevers consisting of strain-coupled magnetostrictive and piezoelectric (PE) layers are applicable to magnetic-field sensing. For the first bending mode, the magnetic field-induced stress distribution is of equal sign along the cantilever length. Thus, a plate-capacitor electrode configuration encompassing the complete PE layer may be used for collecting the strain-induced charge. For higher order modes, stress regions of the opposite sign occur in the cantilever length direction. To prevent charge cancellation and to harvest the piezoelectric induced charge efficiently, segmented electrodes are employed. This study investigates the effect of the electrode configuration on the signal-to-noise ratio (SNR) for higher order bending modes. The charges collected by the electrodes are calculated using a finite element method simulation considering the mechanical, electrical, and magnetic properties of the cantilever. By combination with an analytic noise model, taking into account the sensor and amplifier noise sources, the SNR is obtained. We analyze a 3 mm long, 1 mm wide, and 50 μm thick silicon cantilever with layers of 2 μm magnetostrictive soft amorphous metal (FeCoSiB) and 2 μm piezoelectric aluminum nitride. We demonstrate that an SNR-optimized electrode design yields an SNR improvement by 2.3 dB and 2.4 dB for the second and third bending modes compared to a signal optimized design.

A surface-acoustic-wave (SAW) magnetic-field sensor utilizing fundamental, first- and second-order Love-wave modes is investigated. A 4.5 μm SiO2 guiding layer on an ST-cut quartz substrate is coated with a 200 nm (Fe90Co10)78Si12B10 magnetostrictive layer in a delay-line configuration. Love-waves are excited and detected by two interdigital transducers (IDT). The delta-E effect in the magnetostrictive layer causes a phase change with applied magnetic field. A sensitivity of 1250°/mT is measured for the fundamental Love mode at 263 MHz. For the first-order Love mode a value of 45°/mT is obtained at 352 MHz. This result is compared to finite-element-method (FEM) simulations using one-dimensional (1D) and two-and-a-half-dimensional (2.5 D) models. The FEM simulations confirm the large drop in sensitivity as the first-order mode is close to cut-off. For multi-mode operation, we identify as a suitable geometry a guiding layer to wavelength ratio of hGL/λ≈1.5 for an IDT pitch of p=12 μm. For this layer configuration, the first three modes are sufficiently far away from cut-off and show good sensitivity.

Three different finite element method (FEM) models of a surface acoustic wave (SAW) based magnetic field sensor with increasing complexity from one dimensional to three dimensional model are presented and compared. These sensors are designed to measure weak biomagnetic fields in an unshielded environment at room temperature, using a magnetostrictive layer at the surface to convert a magnetic signal to a change in SAW velocity.

We report on the direct observation of spin wave and elastic wave emission from magnetic domain walls in ferromagnetic thin films. Driven by alternating homogeneous magnetic fields the magnetic domain walls act as coherent magnetisation wave sources. Directional and low damped elastic waves below and above the ferromagnetic resonance are excited. The wave vector of the magnetoelastically induced acoustic waves is tuned by varying the excitation frequency. The occurrence of elastic wave emission is proved by a combination of micromagnetic and mechanical finite element simulations. Domain wall emitted magnetostatic surface spin waves occur at higher frequencies, which characteristics are confirmed by micromagnetic simulations. The distinct modes of magnetisation wave excitation from micromagnetic objects are a general physical phenomenon relevant for dynamic magnetisation processes in structured magnetic films. Magnetic domain walls can act as reconfigurable antennas for spin wave and elastic wave generation. The wave orientation can be controlled separately via the domain wall orientation for elastic waves and via magnetization orientation for magnetostatic surface spin waves.

We present a comprehensive study of a magnetic sensor system that benefits from a new technique to substantially increase the magnetoelastic coupling of surface acoustic waves (SAW). The device uses shear horizontal acoustic surface waves that are guided by a fused silica layer with an amorphous magnetostrictive FeCoSiB thin film on top. The velocity of these so-called Love waves follows the magnetoelastically-induced changes of the shear modulus according to the magnetic field present. The SAW sensor is operated in a delay line configuration at approximately 150 MHz and translates the magnetic field to a time delay and a related phase shift. The fundamentals of this sensor concept are motivated by magnetic and mechanical simulations. They are experimentally verified using customized low-noise readout electronics. With an extremely low magnetic noise level of ≈100 pT/ √(Hz) , a bandwidth of 50 kHz and a dynamic range of 120 dB, this magnetic field sensor system shows outstanding characteristics. A range of additional measures to further increase the sensitivity are investigated with simulations.

The intrinsic strain at coupled components in magnetoelectric composites plays an important role for the properties and function of these materials. In this in situ X-ray nanodiffraction experiment, the coating-induced as well as the magnetic-field-induced strain at the coupled interface of complex magnetoelectric microcomposites were investigated. These consist of piezoelectric ZnO microrods coated with an amorphous layer of magnetostrictive (Fe90Co10)78Si12B10. While the intrinsic strain is in the range of 10-4, the magnetic-field-induced strain is within 10-5, one order of magnitude smaller. Additionally, the strain relaxation distance of around 5 μm for both kinds of strain superposes indicating a correlation. The value of both intrinsic and magnetic-field-induced strain can be manipulated by the diameter of the rodlike composite. The intrinsic interface strain within the ZnO increases exponentially by decreasing the rod diameter while the magnetic-field-induced strain increases linearly within the given range. This study shows that miniaturizing has a huge impact on magnetoelectric composite properties, resulting in a strongly enhanced strain field and magnetic response.

The signal-to-noise ratio (SNR) is investigated for compound magnetoelectric (ME) sensors on cantilever substrates (SUBs) for the detection of low-level magnetic fields. Operated at the mechanical resonance, the magnetic field deforming the magnetostrictive (MS) layer causes a resonant bending-mode response in the ME cantilever. The deformation of the piezoelectric (PE) layer allows for the extraction of a voltage or charge signal. Here, the influence of the PE layer thickness and electrode length on the SNR is evaluated in a theoretical study. The signal levels are calculated using the finite-element method. Noise voltages are calculated including the intrinsic electric noise of the ME sensor and amplifier noise for the case of a voltage amplifier and a charge amplifier. AlN and PZT are considered as PE materials. For a cantilever geometry with 10 mm-length, 10 mm-width, and 300 μm-thick silicon SUB and a Metglas MS layer of 2 μm thickness, a limit of detection (LOD) in the pT-range is predicted for 2 μm-thick AlN layers, while the LOD of PZT ME sensors is approximately one order of magnitude worse. A doubling of the SNR is obtained for choosing an upper electrode covering only the fixed side of the cantilever. Operation with a charge amplifier shows at least ~50% better SNR values compared with PE voltage amplification.

This paper investigates the resonant bending-mode response of cantilever magnetoelectric (ME) sensors, with focus on the magnetic behavior in an external applied magnetic field, in a theoretical study. A system of coupled linear elastostatic/elastodynamic and electrostatic/magnetostatic equations is solved using 2-D and 3-D finite-element method simulations. The magnetic field is applied at the boundaries of an air-filled volume, surrounding the whole ME sensor, to consider the geometry-dependent deformation of the magnetic field in the presence of materials with high permeability. The deformation of the magnetostrictive (MS) material is calculated and generates an electric potential across a piezoelectric (PE) layer. Structuring the conductive MS layer is necessary to define a pickup region, if the MS layer is produced on top of the PE layer, to enhance the sensor output. For efficient excitation of the resonant bending mode, the tip of the cantilever also needs to be covered with an MS material. Thus, an air gap is necessary to electrically insulate both MS regions and has to be as small as possible to not decrease the magnetic field penetrating into the MS layer. The induced electric potential across the pickup region is optimized for a Metglas-AlN-Si thin-film ME sensor with an length: width: height ratio of 100:20:3. 2-D simulations are performed showing reasonable agreement in induced voltage with approximately 20% deviation compared with 3-D simulations, but with much lower computation times.

Two methods for the fabrication of flexible and stretchable photonic crystal slabs are demonstrated and compared. In both cases a periodically nanostructured polydimethylsiloxane (PDMS) membrane is used as substrate. The first method is based on oblique-angle vapor deposition of SiO as a high refractive index material onto the nanostructured membrane. The deposition is made at an angle of 45° to the surface. The grooves of the nanostructure are aligned such that shading effects cause an inhomogeneous layer thickness distribution on the surface. This supports controlled, periodic cracking of the high index layer upon stretching. In the second approach ZnO nanoparticles are spin-coated on the nanostructured PDMS membrane. Here, the membrane can be stretched and serves as a photonic crystal slab without the need of any further treatment. For both types of flexible photonic crystal slabs a shift of the guided mode resonances to longer wavelengths is observed upon stretching. For a 20% strain perpendicular to the grating grooves a resonance shift of more than 50 nm is obtained.