Coupling Layer Research Articles

Study of the role of abyssal ocean stratification in the rearrangement of potential vorticity through the water column

Abstract. Observations of abyssal variability performed in the Ionian Sea (Mediterranean Sea) have revealed the presence of a dense, stable abyssal layer, whose thermohaline and dynamical properties changed drastically over a decade. Building upon these available observations, we aim to investigate the role that stratification can play in the transmission of vorticity throughout the water column to the abyss and, in turn, in the redistribution of energy stored in the deep sea, with a set of stationary states. A quasi-geostrophic level model equipped with four coupled layers, a free surface, and a mathematical artifice for parameterizing decadal time evolution has been considered, proving that the relative-thickness and relative-density differences among the layers are the two critical factors that determine the dynamical characteristics of this rearrangement. The variability in ocean stratification is a relevant aspect that can activate deep and intermediate dynamics, engaging in the propagation and stabilization of signals throughout the water column. This demonstrates the non-negligible active connection between the dynamics of the bottom layers and the surface. The theoretical framework and parameterization used are based on specific observations made in the Ionian Sea over the last decades but retain general applicability to all ocean basins that are characterized by the presence of a stratified, dense water mass in their deep and intermediate layers.

The Influence of Coupling-Specific Parameters and Structural Parameters on the Electromechanical Impedance of Acoustic Emission Sensors

Acoustic emission (AE) sensors are widely used for testing and monitoring purposes, necessitating effective field-testing methods to assess their functionality during use, ideally resulting in a method for self-diagnostic. A novel approach for field-testing is to measure the electromechanical impedance (EMI) of the AE sensor. This method requires minimal additional equipment and eliminates human interaction, which is needed for current field-tests like pencil-lead break tests. However, the EMI includes the mechanical impedances of the sensor, the coupling layer, and the structure. Therefore, the measurements contain information about all three and influences of the structure and the coupling layer need to be investigated to be able to establish a method for self-diagnosis in field. Additionally, the piezoelectric effect is temperature-dependent, which affects the measured EMI spectra and may result in erroneous assessments of the sensor's condition if not accounted for. This work presents experimental studies on the influence of measuring equipment, environmental temperature, coupling-specific parameters and structural parameters on the EMI of AE sensors. Moreover, numerical simulations have been conducted to provide additional support and to extend the experimental studies of the latter two. To ensure reproducible sensor coupling to a structure, a setup was constructed to couple the sensor to the structure at the same position and with the same force. The thickness of the coupling layer is determined by a small amount of silicon carbide particles with a specific diameter. This setup is also used to examine the effect of structural parameters.

BGFlow: Brightness-guided normalizing flow for low-light image enhancement

Low-light image enhancement poses significant challenges due to its ill-posed nature. Recently, deep learning-based methods have attempted to establish a unified mapping relationship between normal-light images and their low-light versions but frequently struggle to capture the intricate variations in brightness conditions. As a result, these methods often suffer from overexposure, underexposure, amplified noise, and distorted colors. To tackle these issues, we propose a brightness-guided normalizing flow framework, dubbed BGFlow, for low-light image enhancement. Specifically, we recognize that low-frequency sub-bands in the wavelet domain carry significant brightness information. To effectively capture the intricate variations in brightness within an image, we design a transformer-based multi-scale wavelet-domain encoder to extract brightness information from the multi-scale features of the low-frequency sub-bands. The extracted brightness feature maps, at different scales, are then injected into the brightness-guided affine coupling layer to guide the training of the conditional normalizing flow module. Extensive experimental evaluations demonstrate the superiority of BGFlow over existing deep learning-based approaches in both qualitative and quantitative assessments. Moreover, we also showcase the exceptional performance of BGFlow on the underwater image enhancement task.

Mechanism of Coupled Upper Troposphere and Boundary Layer Induces Two Types of Short‐Term Heavy Rainfall Along the Eastern Foothills of the Taihang Mountains

AbstractUsing 11 years of hourly merged rainfall records and ERA reanalysis data, this paper reveals two major circulation modes leading to two types of short‐term heavy rainfall (STHR) along the Taihang Mountains' eastern foothills, and further explains their mechanisms. One circulation mode has a distinct warm anomaly at 300 hPa covering most areas of North China, together with the boundary‐layer westerly anomaly occurring in North China and its southern region (UTWA‐BLWA). UTWA‐BLWA effectively contributes to the reinforcement of the upper‐level divergence and the low‐level moisture convergence by promoting the strengthening of upper anticyclonic and low‐level southwesterly anomalies. The combined effects of low‐level jet (LLJ) and topographic uplift form the central‐northern STHR pattern. The other circulation structure has a 300‐hPa warm anomaly located to the southeastern Russia and a prominent 300‐hPa cold anomaly covering the south, together with the boundary‐layer easterly anomaly occurring over the whole region of eastern China (UTCA‐BLEA). The southern STHR pattern is attributed to the exit of the boundary‐layer jet (BLJ) over lower elevations due to moist transport and dynamic uplift associated with the easterly anomaly. The results indicate that the locations of STHR are related to the direction, intensity, and height of the LLJ. The findings highlight that the upper‐tropospheric temperature anomalies (UTTA) and boundary‐layer easterly flow jointly modulate heavy rainfall. Analysis of the coupled upper troposphere and boundary layer could help understand and forecast heavy rainfall.

Non-similar solution of Casson fluid flow over a curved stretching surface with viscous dissipation; Artificial neural network analysis

PurposeThe main focus is to provide a non-similar solution for the magnetohydrodynamic (MHD) flow of Casson fluid over a curved stretching surface through the novel technique of the artificial intelligence (AI)-based Lavenberg–Marquardt scheme of an artificial neural network (ANN). The effects of joule heating, viscous dissipation and non-linear thermal radiation are discussed in relation to the thermal behavior of Casson fluid.Design/methodology/approachThe non-linear coupled boundary layer equations are transformed into a non-linear dimensionless Partial Differential Equation (PDE) by using a non-similar transformation. The local non-similar technique is utilized to truncate the non-similar dimensionless system up to 2nd order, which is treated as coupled ordinary differential equations (ODEs). The coupled system of ODEs is solved numerically via bvp4c. The data sets are constructed numerically and then implemented by the ANN.FindingsThe results indicate that the non-linear radiation parameter increases the fluid temperature. The Casson parameter reduces the fluid velocity as well as the temperature. The mean squared error (MSE), regression plot, error histogram, error analysis of skin friction, and local Nusselt number are presented. Furthermore, the regression values of skin friction and local Nusselt number are obtained as 0.99993 and 0.99997, respectively. The ANN predicted values of skin friction and the local Nusselt number show stability and convergence with high accuracy.Originality/valueAI-based ANNs have not been applied to non-similar solutions of curved stretching surfaces with Casson fluid model, with viscous dissipation. Moreover, the authors of this study employed Levenberg–Marquardt supervised learning to investigate the non-similar solution of the MHD Casson fluid model over a curved stretching surface with non-linear thermal radiation and joule heating. The governing boundary layer equations are transformed into a non-linear, dimensionless PDE by using a non-similar transformation. The local non-similar technique is utilized to truncate the non-similar dimensionless system up to 2nd order, which is treated as coupled ODEs. The coupled system of ODEs is solved numerically via bvp4c. The data sets are constructed numerically and then implemented by the ANN.

Reduced decay in Josephson coupling across ferromagnetic junctions with spin–orbit coupling layers

The generation of Sz = 1 triplet Cooper pairs has been predicted theoretically in superconducting–ferromagnetic hybrid heterostructures in the presence of spin–orbit coupling [F. S. Bergeret and I. V. Tokatly, Phys. Rev. B 89, 134517 (2014) and Jacobsen et al., Sci. Rep. 6, 23926 (2016)]. In this study, we experimentally investigate vertical Josephson junctions where the weak link is formed from a ferromagnetic layer with perpendicular magnetic anisotropy sandwiched by two non-magnetic layers with weak or strong spin–orbit coupling. We find that the decay of the Josephson coupling is reduced in the latter case, possibly indicating the presence of Sz = 1 spin-triplet correlations. We speculate that the canted magnetization required for these correlations is provided by the interaction of magnetization with Meissner effect in the superconducting layers.

Preparation and performance evaluation of heat resistant and salt resistant anionic fluid loss reducer for water‐based drilling fluid

AbstractIn this investigation, a new micro‐crosslinked anionic polymer resistant to elevated temperature and high salinity, PKDASN, was synthesized using 3‐chloropropyltriethoxysilane (KMB703), N, N‐Dimethylacrylamide (DMAM), 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS), N‐vinyl caprolactam (NVCL), and sodium (4‐vinyl phenyl)methanesulfonate (SVM) employing free radical polymerization in a water‐based solution. The structure of PKDASN was analyzed using Fourier‐transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and X‐ray photoelectron spectroscopy, while its microstructure was analyzed using scanning electron microscopy. Thermogravimetric analysis showed that the pyrolysis temperature of PKDASN was above 294°C. Adding KMB703 enables the polymer to form a dense and stable spatial network. This intensified polymer network could interact with bentonite via intermolecular force and Coulomb force and form a dual grid structure, which presents impressive stability and control of filtration in saltwater. This is mainly achieved through creating a “silane coupling layer” on the particle surface by KMB703, which facilitates the crosslinking and aggregation of the polymer, thereby reinforcing the polymer's framework. This implies that under high‐temperature conditions of 230°C, 3 wt% PKDASN can improve the filtration effectiveness of drilling fluids and exhibit resistance to 15 wt% NaCl contamination. American Petroleum Institute filtration(FLAPI) and High temperature and high pressure filtration(FLHTHP) values were 4.6 and 23.0 mL, respectively. Therefore, this investigation provides a novel approach to utilizing the designated silane agent for the advancement of filtration loss additives in drilling fluids resistant to elevated temperature and high salinity.

A novel antibacterial and wear-resistant strategy based on metal surface micro-texture nitriding coupled functional mesoporous silicon coating

Modified metal layers coupling durable antifouling and antibacterial properties have garnered considerable interest in various fields, including but not limited to medical equipment, kitchen utensils, public facilities, and specific industrial applications, such as transportation, energy utilization, and aerospace. Nevertheless, wear and corrosion resulting from harsh operating environments can significantly compromise the modified metal layers, leading to diminished antifouling and antibacterial capabilities. Currently, maintaining excellent antibacterial properties on the surface of metal-modified layers under complex working conditions remains a key challenge for metal protection technology. Herein, we innovatively propose a ternary collaborative strategy to optimize and extend the antifouling and antibacterial activity of metal substrate surfaces. Firstly, laser surface texturing (LST) is used to create micro-textured topography on the metal surface to serve as a reservoir for collecting debris and storing functionalized nanoparticles. Then, the surface micro-textures are treated with plasma nitriding to form a wear-resistant passivation layer that protects the aforementioned microstructures. Finally, a lubricant containing functional mesoporous silicon nanoparticles (Ag2O-MSNs@OTES) is coated on the metal surface, which not only reduces the friction coefficient but also achieves antibacterial and antifouling effects by continuously releasing silver ions from the mesoporous silicon spheres. Employing the aforementioned ternary coordination strategy, the fabricated coupling layer exhibits not only exceptional antifriction and wear properties but also remarkable antibacterial efficacy against both E. coli and S. aureus, attributed to the Ag2O-MSNs@OTES. Therefore, the wear-resisting and antibacterial coupling layer for the protection of metal surfaces has promising and versatile applications in wide areas.

Robust ultrasonically welded CF/PEI-CF/epoxy composite joints upon tailoring the thermoplastic resin thickness at the welding interface

The objective of this study was to develop robust carbon fiber/epoxy (CF/epoxy)-carbon fiber/polyetherimide (CF/PEI) hybrid joint upon an ultrasonic welding process. The co-curing of a PEI coupling layer (CL) on the surface of the CF/epoxy composite makes it “meltable and weldable”. The CF/epoxy was then ultrasonically welded with the CF/PEI using different combinations of energy director (ED) and CL thicknesses. The results showed that high-quality welding line could be obtained by carrying out coupling-optimization to the thicknesses of the EDs and CLs using an optimal welding displacement. For example, a largest lap-shear strength (LSS) of 35.3 MPa was achieved when both of the ED and CL possessed an optimal thickness of 175 μm. In this case, a cohesive failure within either the CF/PEI or the CF/epoxy substrate took place during the single-lap shear test of the hybrid joints. Predictably, this study provides a promising strategy for the production of high-performance hybrid composite joints upon tailoring the thicknesses of the EDs and the CLs for the ultrasonic welding process.

Tunable liquid crystal double-layer frequency selective surface with wide transmission band and small insertion loss

ABSTRACT In this paper, a tunable Frequency Selective Surface (FSS) based on liquid crystal (LC) with a wide transmission band, large tuning range, high tuning rate, and miniaturization is designed. First, a single-layer FSS is developed with two frequency selective layers and one LC tunable layer. The simulation and experiment results show that the single-layer FSS has a transmission bandwidth greater than 4.25 GHz, and the LC change can make the center frequency of the transmitted band shift to the lower frequency by 576 MHz, with a tuning rate of 4.2%. Subsequently, a double-layer FSS is designed by adding a coupling layer to the single-layer FSS, achieving a flat-top passband and enhancing the tuning rate. Simulation and experimental validation show that altering the LC state enables continuous tuning of the center frequency of the double-layer FSS from 14.95 GHz to 13.86 GHz, with a tuning rate of 7.2%. This structure exhibits a flat-top passband wider than 5.7 GHz, a relative bandwidth of 41%, and a rectangular coefficient below 1.877. Moreover, the double-layer FSS demonstrates favorable polarization stabilization and wide incidence angle stabilisation properties in various states.

Facet-selective growth of halide perovskite/2D semiconductor van der Waals heterostructures for improved optical gain and lasing

The tunable properties of halide perovskite/two dimensional (2D) semiconductor mixed-dimensional van der Waals heterostructures offer high flexibility for innovating optoelectronic and photonic devices. However, the general and robust growth of high-quality monocrystalline halide perovskite/2D semiconductor heterostructures with attractive optical properties has remained challenging. Here, we demonstrate a universal van der Waals heteroepitaxy strategy to synthesize a library of facet-specific single-crystalline halide perovskite/2D semiconductor (multi)heterostructures. The obtained heterostructures can be broadly tailored by selecting the coupling layer of interest, and can include perovskites varying from all-inorganic to organic-inorganic hybrid counterparts, individual transition metal dichalcogenides or 2D heterojunctions. The CsPbI2Br/WSe2 heterostructures demonstrate ultrahigh optical gain coefficient, reduced gain threshold and prolonged gain lifetime, which are attributed to the reduced energetic disorder. Accordingly, the self-organized halide perovskite/2D semiconductor heterostructure lasers show highly reproducible single-mode lasing with largely reduced lasing threshold and improved stability. Our findings provide a high-quality and versatile material platform for probing unique optoelectronic and photonic physics and developing further electrically driven on-chip lasers, nanophotonic devices and electronic-photonic integrated systems.

Even-odd-layer-dependent symmetry breaking in synthetic antiferromagnets

In this work we examine synthetic antiferromagnetic structures consisting of two, three, and four antiferromagnetic coupled layers, i.e. bilayers, trilayers, and tetralayers. We vary the thickness of the ferromagnetic layers across all structures and, using a macrospin formalism, find that the nearest neighbor exchange interaction between layers is consistent across all structures for a given thickness of the ferromagnetic layer. Our model and experimental results demonstrate significant differences in how the static equilibrium states of even and odd-layered structures evolve as a function of the external field. Even layered structures continuously evolve from a collinear antiferromagnetic state to a spin canted non-collinear magnetic configuration that is mirror-symmetric about the external field. In contrast, odd-layered structures begin with a ferrimagnetic ground state; at a critical field, the ferrimagnetic ground state evolves into a non-collinear state with broken symmetry. Specifically, the magnetic moments found in the odd-layered samples possess stable static equilibrium states that are no longer mirror-symmetric about the external field after a critical field is reached.

Effect of the paste spreadability on ultrasonic transducer fabricated by pressureless sintering of nano-Ag

Paste spreadability is critical to paste spread layer and thus the quality of final product in pressureless sintering of nano-Ag, but the metrics and the underlying mechanics have not yet been well acknowledged. In this work, various ultrasonic transducers are fabricated by pressureless sintering of various nano-Ag pastes. Particle dynamics mechanism during the paste spreading process and the relationship between paste viscosity and spreadability are clarified. The influences of paste spreadability on dynamic performances of transducer are analysed, and the underlying mechanisms are also investigated. The results show that the normalized mass of Ag NPs is basically positively correlated with the flatness of the coupling layer, and the flatness of the coupling layer is also positively correlated with the peak-to-peak voltage and SNR of the transducer. The attenuation in the far-field scattering process mainly depends on the porosity of the coupling layer.

Synthesizing Lithuanian voice replacement for laryngeal cancer patients with Pareto-optimized flow-based generative synthesis network

This study presents a Pareto optimized flow-based generative network for speech synthesis - the P-GLOW model in Lithuanian speech synthesis for substituting original voices affected by cancer-related pathologies. Comparing this pure Lithuanian model with an English model trained on Lithuanian phonemes, the study emphasizes the impact of language-specific characteristics on performance, illustrating the advantages of tailored, language-specific models for speech substitution for impaired persons. Our methodology integrates generative models with an architecture based on 12 coupling layers, 1x1 invertible convolutions, and dilated convolutions with gated hyperbolic tangent activation functions. This design facilitates the effective transformation of waveform inputs into Mel spectrograms, enabling the synthesis of high-quality speech audio. The proposed, Pareto optimized, native Lithuanian model achieved a MOS of 4.2 ± 0.1 and an SMOS of 3.9 ± 0.2, while the baseline model (English language model trained on top with Lithuanian phonemes) scored lower with a MOS of 3.8 ± 0.2 and an SMOS of 3.4 ± 0.3. In terms of the Mel Cepstral Distortion (MCD), Voiced/Unvoiced Decision Error (VDE), Glottal-to-Noise Excitation Ratio (GPE), and Frame Fidelity Error (FFE) scores, the proposed method achieved an MCD of 3.2 dB ± 0.2, a VDE of 5.6% ± 1.0, a GPE of 7.9% ± 1.4, and an FFE of 9.7% ± 2.0, outperforming the baseline method which scored higher with an MCD of 4.6 dB ± 0.3, a VDE of 10.8% ± 1.9, a GPE of 14.5% ± 2.4, and an FFE of 18.7% ± 2.8. Log Likelihood Ratio (LLR), Weighted Spectral Slope (WSS), and Perceptual Evaluation of Speech Quality (PESQ) scores also showed strong improvement. The proposed method achieved an LLR of 0.5 ± 0.05, a WSS of 0.3 ± 0.03, and a PESQ of 4.2 ± 0.1, while the baseline method scored lower with an LLR of 0.8 ± 0.08, a WSS of 0.5 ± 0.05, and a PESQ of 3.6 ± 0.2. The Speech Intelligibility Index (SII) and Short-Time Objective Intelligibility (STOI) metrics for restored alaryngeal speech were also high. The proposed method achieved an SII of 0.75 ± 0.05 and an STOI of 0.85 ± 0.03, while the baseline method scored lower with an SII of 0.65 ± 0.05 and an STOI of 0.75 ± 0.04. The evaluation results demonstrate that our approach was able to effectively synthesize high-quality Lithuanian speech audio restoring the input signal from distorted alaryngeal speech.

Low-Voltage High-Frequency Lamb-Wave-Driven Micromotors.

By leveraging the benefits of a high energy density, miniaturization and integration, acoustic-wave-driven micromotors have recently emerged as powerful tools for microfluidic actuation. In this study, a Lamb-wave-driven micromotor is proposed for the first time. This motor consists of a ring-shaped Lamb wave actuator array with a rotor and a fluid coupling layer in between. On a driving mechanism level, high-frequency Lamb waves of 380 MHz generate strong acoustic streaming effects over an extremely short distance; on a mechanical design level, each Lamb wave actuator incorporates a reflector on one side of the actuator, while an acoustic opening is incorporated on the other side to limit wave energy leakage; and on electrical design level, the electrodes placed on the two sides of the film enhance the capacitance in the vertical direction, which facilitates impedance matching within a smaller area. As a result, the Lamb-wave-driven solution features a much lower driving voltage and a smaller size compared with conventional surface acoustic-wave-driven solutions. For an improved motor performance, actuator array configurations, rotor sizes, and liquid coupling layer thicknesses are examined via simulations and experiments. The results show the micromotor with a rotor with a diameter of 5 mm can achieve a maximum angular velocity of 250 rpm with an input voltage of 6 V. The proposed micromotor is a new prototype for acoustic-wave-driven actuators and demonstrates potential for lab-on-a-chip applications.

Modeling of Acoustic Coupling of Ultrasonic Probes for High-Speed Rail Track Inspection

The paper presents the modeling of transmission of the ultrasonic plane wave through an uniform liquid layer. The considered sources of the ultrasonic wave were normal (straight) beam longitudinal wave probes and angle beam sheer waves probes commonly used in non-destructive testing. Coupling losses (CL) introduced by the presence of the coupling layer are discussed and determined applying the numerical procedure. The modeling applies to both monochromatic waves and short ultrasonic pulses with a specified frequency bandwidth. Model implementation and validation was performed using a specialized software. The predictions of the model were confirmed by coupling losses measurements for a normal beam longitudinal wave probe with a delay line made of polymethyl methacrylate (PMMA). The developed model can be useful in designing ultrasonic probes for high-speed rail track inspections, especially for establishing the optimal thickness of the water coupling layer and estimation of coupling losses, due to inevitable changes of the water gap during mobile rail inspection.

Domain wall magnetic tunnel junction-based artificial synapses and neurons for all-spin neuromorphic hardware

We report a breakthrough in the hardware implementation of energy-efficient all-spin synapse and neuron devices for highly scalable integrated neuromorphic circuits. Our work demonstrates the successful execution of all-spin synapse and activation function generator using domain wall-magnetic tunnel junctions. By harnessing the synergistic effects of spin-orbit torque and interfacial Dzyaloshinskii-Moriya interaction in selectively etched spin-orbit coupling layers, we achieve a programmable multi-state synaptic device with high reliability. Our first-principles calculations confirm that the reduced atomic distance between 5d and 3d atoms enhances Dzyaloshinskii-Moriya interaction, leading to stable domain wall pinning. Our experimental results, supported by visualizing energy landscapes and theoretical simulations, validate the proposed mechanism. Furthermore, we demonstrate a spin-neuron with a sigmoidal activation function, enabling high operation frequency up to 20 MHz and low energy consumption of 508 fJ/operation. A neuron circuit design with a compact sigmoidal cell area and low power consumption is also presented, along with corroborated experimental implementation. Our findings highlight the great potential of domain wall-magnetic tunnel junctions in the development of all-spin neuromorphic computing hardware, offering exciting possibilities for energy-efficient and scalable neural network architectures.

Exploring orientation-dependent interface engineering in manganite heterostructures

The crucial role of interface engineering in controlling functionality has been well documented in the (001)-orientated perovskite oxide heterostructures; however, limited attention has been given to other epitaxial orientations. In this study, the (La,Sr)MnO3 heterostructure is selected to present the epitaxial-orientation-dependent interface engineering strategies based on magnetoelectric coupling and oxygen octahedral coupling. When capped by a ferroelectric PbTiO3 layer for interlayer magnetoelectric coupling, the (001) (La,Sr)MnO3 layer exhibits the most significant magnetic modulations compared to (110) and (111) counterparts. This can be attributed to the PbTiO3's out-of-plane polarization that depends on the epitaxial orientations. Also, if considering the interfacial oxygen octahedral structure in terms of epitaxial orientations, the buffer (or cap) layer hosts the most part of interfacial oxygen octahedra and, thus, plays a dominant role in controlling oxygen octahedral coupling of (001)-orientated [or (110)-orientated] perovskite heterostructures. This is consistent with our observations that for the (001) [or (110)] (La,Sr)MnO3 heterostructures, the DyScO3 buffer layer offers the more (or less) effective magnetic modulations compared to the cap one. These findings underscore the orientation-dependent nature of interface engineering in manganite heterostructures as well as in other perovskite heterostructures for tailoring functionalities.

Design, analysis, and testing of a variable-stiffness soft grabbing robot coupling particle jamming and layer jamming

Variable-stiffness soft robots feature high flexibility in motion and high stiffness in task execution, so they are in wide demand. A coupled variable stiffening method and actuator structures based on layer jamming and particle jamming were developed. The influences of different coupled modes of particles and layers on variable stiffening were evaluated, and coupled variable-stiffness soft actuators were designed. Then, the finite element method was used to simulate the multi-airbag driving structure and variable-stiffness mechanical models were established for three coupled structures to optimize parameters influencing the stiffness. Furthermore, the prototypes of the coupled variable-stiffness soft actuators were prepared, and the test platform was built to estimate the bending performance and variable stiffening capacity. Finally, a soft grabbing robot was prepared using the coupled variable-stiffness soft actuator and application tests were performed. The theoretical analysis and test results show that the soft grabbing robot can grab objects in diverse shapes and the maximum mass of objects that can be grasped is 1.25 kg, which verifies the variable stiffening capacity of the coupled soft actuator. The research provides new theoretical and technological support for the design and application of variable-stiffness soft robots.

Fano resonance-enhanced planar waveguide sensor utilizing MoS2 for high-performance sensing application

Sensing performance of a Fano resonance waveguide based sensor having a MoS2 material assisted with low refractive index coupling prism BK7 is analyzed. Position of MoS2 is optimized by considering two six-layer structural configurations i.e. PAMCFS and PMACFS and their results are compared at particular guiding layer thickness 500 nm and coupling layer thickness 700 nm. The reflectance formula of proposed six-layer waveguide is obtained using Fresnel’s equations. Our analysis shows that the PAMCFS waveguide gives better sensing performance than PMACFS. Further, sensing parameters is analyzed for different thickness of coupling layer and guiding layer. The maximum obtained sensitivity for zero order Fano resonance mode in intensity interrogation of the proposed PAMCFS waveguide structure is 6.847 × 106 a.u.-RIU–1 at guiding layer thickness 800 nm and coupling layer thickness 1000 nm. Also, at these thicknesses, FWHM is obtained in order of ∼10−6 while the achieved detection accuracy and figure of merit in order of ∼107 and ∼106 respectively.