Thickness Modulation Research Articles

Role of stretch-activated channels in light-generated action potentials mediated by an intramembrane molecular photoswitch

BackgroundThe use of light to control the activity of living cells is a promising approach in cardiac research due to its unparalleled spatio-temporal selectivity and minimal invasiveness. Ziapin2, a newly synthesized azobenzene compound, has recently been reported as an efficient tool for light-driven modulation of excitation-contraction coupling (ECC) in human-induced pluripotent stem cells–derived cardiomyocytes. However, the exact biophysical mechanism of this process remains incompletely understood.MethodsTo address this, we performed a detailed electrophysiological characterization in a more mature cardiac model, specifically adult mouse ventricular myocytes (AMVMs).ResultsOur in vitro results demonstrate that Ziapin2 can photomodulate cardiac ECC in mature AMVMs without affecting the main transporters and receptors located within the sarcolemma. We established a connection between Ziapin2-induced membrane thickness modulation and light-generated action potentials by showcasing the pivotal role of stretch-activated channels (SACs). Notably, our experimental findings, through pharmacological blockade, suggest that non-selective SACs might serve as the biological culprit responsible for the effect.ConclusionsTaken together, these findings elucidate the intricacies of Ziapin2-mediated photostimulation mechanism and open new perspectives for its application in cardiac research.

Bragg resonances in the yttrium iron garnet – platinum – yttrium iron garnet layered structure

We studied theoretically the interaction between the spin current in a conductor with a strong spin-orbit coupling (platinum, Pt) and the spin wave in yttrium iron garnet ferromagnetic layers (YIG) with periodic thickness modulation under conditions of Bragg resonances and interlayer coupling. It is shown that in the YIG/Pt/YIG sandwich structure the conditions for two Bragg resonances in the first Brillouin area in the spin wave spectrum are fulfilled. The spin current in Pt allows frequency tuning of the resonances and control the depth of the spin wave band gap corresponding to the resonance conditions.

Ultrahighly Sensitive Flexible Pressure Sensors with Dual-Mode Response Based on Monolayer Films of Calcium Niobate Nanosheets.

Flexible pressure sensors present enormous potential for applications in health monitoring, human-machine interfacing, and electronic skins (e-skin). However, at the cost of flexibility, the design of flexible pressure sensors has been facing the trade off between high sensitivity and wide sensing range. Herein, we propose a sandwiched structure composed of monolayer films of calcium niobate nanosheets to endow the device with both ultrahigh sensitivity and a wide sensing range. Tunable contact between the two electrodes of the pressure sensor through the gaps in the insulative monolayer film and precise thickness modulation of the monolayer films at the nanoscale result in an ultrahigh sensitivity and wide sensing range of the sensors. By virtue of these two traits, the pressure sensor distinguishes itself with unprecedented performances of ultrahigh sensitivity (6.43 × 104 kPa-1), a wide sensing range (1.94-60.00 kPa), a fast response time (<165 ms), and reliable repeatability. In addition, the sensor has a sensing mechanism transition from capacitive mode to piezoresistive mode from low pressure to high pressure. The sensors demonstrates the ability for motion detection of the human body. This work sheds light on the development of highly sensitive flexible pressure sensors.

Thickness modulation influenced mechanical properties of TiN/(CrVTaTiW)Nx multilayer coatings

A novel TiN/(CrVTaTiW)Nx multilayer coating, consisting of the high-entropy alloy nitride and the binary nitride was prepared by DC magnetron sputtering. Detailed investigation about the microstructure and mechanical attributes of the multilayer films was conducted, with particular emphasis on the influence of high entropy nitride (HEN) modulation layer's thickness. The results reveal that all samples exhibited a face-centred cubic (fcc) crystal structure with a (111) preferred orientation. Notably, the hardness and elastic modulus of multilayer films increase with increase of the HEN layer's thickness. When the thickness of the HEN layer reached 4.8 nm, the hardness and elastic modulus of the TiN/(CrVTaTiW)Nx multilayer reached the maximum values of 25.33 GPa and 311.95 GPa, respectively. These results indicate the key role of the HEN layer as a modulation layer within the coating, ultimately demonstrating the importance of thickness on the structure and properties of TiN/(CrVTaTiW)Nx nanomultilayer films.

Mid-Summer observations of water column physical properties and circulation in the San Jorge Gulf (Patagonian Shelf)

In this study, we present detailed insights into the mid-summer density field and flow patterns within the San Jorge Gulf (Patagonian Shelf of Argentina). Utilizing unique data acquired from a towed undulating vehicle equipped with a Conductivity-Temperature-Depth (CTD) sensor and a hull-mounted acoustic Doppler current profiler (ADCP), we investigate the spatial distribution and temporal evolution of the density structure and associated currents. Our observations reveal the presence of a distinctive bottom dome-like structure comprised of dense, cold, and saline waters in the central basin of the gulf during mid-summer. Analysis of the flow dynamics indicates the presence of a near-geostrophic flow regime sustaining this dense water feature. Furthermore, our study highlights the significant role of ageostrophic velocities, primarily influenced by the modulation of pycnocline thickness by M2+M4 internal tides. These findings contribute to a deeper understanding of the oceanographic processes governing the mid-summer dynamics in the San Jorge Gulf, shedding light on the interaction between density structures and associated currents. Such insights are essential for advancing our knowledge of coastal ocean circulation and its implications for various ecological and environmental phenomena.

Thickness and sp3 bond modulation of (Ti/tetrahedral amorphous carbon)n multilayer coatings

Thickness and sp3 bond modulation of (Ti/tetrahedral amorphous carbon)n multilayer coatings

Enhanced adhesion and corrosion resistance through the modulation of a metallic Ti underlayer thickness

In this investigation, TiCN/TiN thin solid film was selected as a protective coating and deposited onto AZ31 alloy through reactive magnetron sputtering. To mitigate the potential failure resulting from the significant physical disparity between the ceramic film and the metal substrate, a Ti thin film was employed as a base layer. Following the deposition process, an analysis was conducted on the structural features, residual stress, fracture morphology, adhesion strength, and corrosion characteristics of the film/substrate system utilizing X-ray diffraction, scanning electron microscopy, scratch testing, and electrochemical workstation. The findings indicate that the incorporation of a Ti metallic underlayer significantly improves the adhesion and corrosion resistance of the TiCN film. However, when the thickness of the Ti layer surpasses 0.37 μm (deposition of 15 min), it leads to the formation of a distinct columnar crystal microstructure, increased residual stress, and diminished adhesion and corrosion resistance. Additionally, this study delves into the corrosion failure mechanisms in a chloride environment and explains the principles of residual stress measurement through XRD.

Tailoring Mechanical and Optical Properties of Sputtered SiNx/BN Coatings.

The swift evolution of contemporary electronics products, such as flexible screens and wearable electronic devices, highlights the significance of flexible protective coatings, which combine superior mechanical and optical properties. Even though the recently developed polymer protective coatings can satisfy requirements for flexibility and transparency, their intrinsic nature often results in a hardness below 1 GPa, rendering them susceptible to scratches. On the other hand, traditional inorganic coatings, known for their high hardness and transparency, fall short of meeting flexibility requirements. In the present study, a SiNx/BN periodical nanolayered coatings (PNCs) structure has been tailored to achieve high mechanical durability, transparency, and flexibility. In SiNx/BN PNCs, the optical and mechanical properties of the single-layer SiNx film are crucial to the overall performance of the PNCs. Therefore, pulse direct current (DC) magnetron sputtering was optimized first to enhance the ionization efficiency of Si and N, thereby promoting their reaction and diminishing the presence of elemental silicon in SiNx. The effects of the pulse frequency and duty cycle on SiNx were evaluated. Additionally, the influence of the thickness ratio and modulation periods on the overall performance of the SiNx/BN PNCs was investigated. As a result, a SiNx/BN coating with sapphire-grade hardness, almost no optical absorption in the visible-near-infrared (vis-NIR) range, high wear resistance, and exceptional flexibility was demonstrated.

Scalable Layer-Controlled Oxidation of Bi2O2Se for Self-Rectifying Memristor Arrays With sub-pA Sneak Currents.

Smart memristors with innovative properties are crucial for the advancement of next-generation information storage and bioinspired neuromorphic computing. However, the presence of significant sneak currents in large-scale memristor arrays results in operational errors and heat accumulation, hindering their practical utility. This study successfully synthesizes a quasi-free-standing Bi2O2Se single-crystalline film and achieves layer-controlled oxidation by developing large-scale UV-assisted intercalative oxidation, resulting β-Bi2SeO5/Bi2O2Se heterostructures. The resulting β-Bi2SeO5/Bi2O2Se memristor demonstrates remarkable self-rectifying resistive switching performance (over 105 for ON/OFF and rectification ratios, as well as nonlinearity) in both nanoscale (through conductive atomic force microscopy) and microscale (through memristor array) regimes. Furthermore, the potential for scalable production of self-rectifying β-Bi2SeO5/Bi2O2Se memristor, achieving sub-pA sneak currents to minimize cross-talk effects in high-density memristor arrays is demonstrated. The memristors also exhibit ultrafast resistive switching (sub-100ns) and low power consumption (1.2 pJ) as characterized by pulse-mode testing. The findings suggest a synergetic effect of interfacial Schottky barriers and oxygen vacancy migration as the self-rectifying switching mechanism, elucidated through controllable β-Bi2SeO5 thickness modulation and theoretical ab initio calculations.

Highly Luminescent Manganese‐Doped 2D Hybrid Perovskite Nanoplatelets with Dual Emissions Controlled Through Layer Thickness Modulation

AbstractDoping semiconductor nanomaterials with manganese ion (Mn2+) introduce a well‐defined photoactive d‐d level within the band structure, paving the way for diverse applications. Although Mn doping in single‐layer 2D hybrid perovskites (n = 1) has been extensively studied, limited research has been conducted on doping with modulation of the layer thickness. Herein, Mn2+ doping in hybrid 2D perovskite nanoplatelets (NPLs), L2An‐1[Pb1‐xMnx]nBr3n+1 (where L = butylammonium, A = methylammonium), with variations in Mn concentration (x = 0–0.60) and layer thickness (n = 1–3) is reported. Substitutional doping of Mn significantly increases the photoluminescence quantum yield as well as the rate of energy transfer efficiency, which strongly depends on the layer thickness of NPLs. The Mn concentration in 2D NPLs determines the rate of forward and backward energy transfer. Low‐temperature emission spectra allow to determine thickness‐dependent exciton binding energy for Mn‐doped 2D NPLs (x = 0.5) with values of 410 ± 11 meV (n = 1), 188 ± 9 meV (n = 2), and 151 ± 17 meV (n = 3). The faster dissociation of band‐edge excitons into free carriers at Mn2+ sites results in high brightness with an excellent CRI of 89.2 for the white light‐emitting diode.

Tunnel silicon nitride manipulated reconfigurable bi-mode nociceptor analog

Neuromorphic applications have shown great promise not only for efficient parallel computing mode to hold certain computational tasks, such as perception and recognition, but also as key biomimetic elements for the intelligent sensory system of next-generation robotics. However, achieving such a biomimetic nociceptor that can adaptively switch operation mode with a stimulation threshold remains a challenge. Through rational design of material properties and device structures, we realized an easily-fabricated, low-energy, and reconfigurable nociceptor. It is capable of threshold-triggered adaptive bi-mode jump that resembles the biological alarm system. With a tunnel silicon nitride (Si3N4) we mimicked the intensity- and rehearsal-triggered jump by means of the tunneling mode transition of Si3N4 dielectric. Under threshold signals the device can also express some common synaptic functions with an extremely low energy density of 33.5 fJ/μm2. In addition, through the modulation of Si3N4 thickness it is relatively easy to fabricate the device with differing pain degree. Our nociceptor analog based on a tunneling layer provides an opportunity for the analog pain alarm system and opens up a new path toward threshold-related novel applications.

Thickness-modulated electronic band structures and exciton behavior of non-van-der-waals 2D Bi2O2Se films

Bi2O2Se, as a non-van-der-waals (non-vdW) interlayer coupling two-dimensional material, its electronic band structures and exciton behavior still merit further in-depth studies, especially in the consideration of thickness tuning degrees of freedom. Here, we reveal the broadband excitonic performance and critical point properties of Bi2O2Se films with different thicknesses (3.54–16.33 nm). Five critical points are determined and assigned to specific optical transitions. Moreover, we observe that electronic bandstructures in the Γ valley are stable with variable thicknesses, while the deeper electron levels received more pronounced thickness modulation. And we first report four excitons in wide spectral range (1.24–6.20 eV) through absorption coefficient fitting. Significantly, due to the strong localization of electrons and holes induced by the intralayer built-in electric field, the exciton binding energy (Eb) value of 3.54 nm-Bi2O2Se (234 meV at Γ position) is apparently larger than typical multi-layer TMDCs, which offering unprecedented opportunities in applications in optoelectronic devices. Furthermore, Eb of two excitons at low energy region (Eb1, Eb2) red-shift with increasing thickness, while Eb of higher-energy excitons (Eb3, Eb4) blue-shift, owing to the dispersion characteristic of the effect dielectric screening effects. Our results are vital to wide-ranging applications of Bi2O2Se from fundamental science to optoelectronic devices.

Mimosa plant leaf-inspired 180° foldable lithium-ion batteries with enhanced electrochemical-mechanical behaviors

Developing high-performance batteries with flexibility is crucial for flexible electronic applications. Although various types of flexible battery designs have been proposed in recent years to improve cycling performance and flexibilities, their application is limited in the most widely used flexible device, namely foldable screen smartphones, due to their inability of 180° folding. Here, inspired by the unique dynamic property of the mimosa plant leaf, we design a bio-inspired flexible lithium-ion battery (FLIB) containing thick energy-storage modules, analogous to the leaflets, and electrical contact part, analogous to the leaf stalk. This design resulted in a FLIB with high flexibility (180° folding and bending), cycling stability, and scalability. Notably, our FLIB demonstrated an improved cycling performance, even under harsh dynamic deformations (10,000-times dynamic 180° folding and 7500-times dynamic bending). The potential mechanisms of mechanical protection for the FLIB were investigated through finite element analysis, further proving its remarkable mechanical endurance. Therefore, our flexible battery design meets the demand of flexible devices for stable power supply under various deformation states. This work sheds new light on the structural innovations and practicality of flexible batteries for future applications.

Experimental Study on High-Sensitivity MoS2Thickness Modulation Refractive Index Sensor Based on SPR-PCF

Experimental Study on High-Sensitivity MoS₂Thickness Modulation Refractive Index Sensor Based on SPR-PCF

Enhance the tribological performance of soft AISI 1045 steel through a CrN/W-DLC/DLC multilayer coating

Special equipment vehicles typically operate in complex environments, leading to wear and failure of the chassis's rotary seal shaft predominantly made of soft AISI 1045 steel. An effective approach to prolong the service life is to apply a hard coating on the working surface. Previous research have primarily concentrated on the coating for hard high-speed steel. However, the significant disparity in physical characteristics between soft AISI 1045 steel and the hard coating results in a weak interface adhesion. This study produces a CrN/W-DLC/DLC multilayer coating on the soft AISI 1045 steel with strong interfacial adhesion and superior friction and wear property through modulation of the CrN transition layer thickness. The multilayer coating consists of five layers, a CrN transition layer, a Cr layer, a Cr/WC alternating layer, a W-DLC/DLC alternating layer, and the topmost DLC layer. The thickest CrN interlayer coating achieves the Lc2 and Lc3 value of 13.9 ± 0.2 N and 20.4 ± 0.9 N. The optimized CrN/W-DLC/DLC coating reduces the internal stress of the DLC coating and enhances its adhesion. Importantly, the average friction coefficient and wear cross-sectional area of the CrN/W-DLC/DLC multilayer coatings decrease accordingly. The thickest CrN interlayer coating exhibits superior outstanding wear resistance evidenced by an average friction coefficient of 0.119, a steady-state friction coefficient of 0.097 and a wear volume of 1.508 × 106 μm3. The presence of a high proportion of sp2 bonds in the thickest CrN interlayer coating, which are susceptible to graphitization, along with a thicker transition layer that enhances the coating's support, leads to narrower wear traces. The primary wear mechanisms observed in the friction and wear test of CrN/W-DLC/DLC coatings are oxidative wear and tribo-abrasive wear. The work provides a significant promise for application in vehicle rotary seal components and a theoretical reference for enhancing the wear resistance of the seal surface.

Biaxial Mechanochromic Behaviors of Mechanically Heterogeneous Colloidal Photonic Crystal Weave

AbstractNon‐close‐packed colloidal photonic crystals (CPhCs) are widely employed in biomimetic strain sensors as they exhibit mechanochromism due to changes in the crystal lattice spacing under stress. However, the structural color of a CPhC film with an incompressible polymer matrix changes with modulation of the film thickness due to deformation, which makes it difficult to visualize the magnitude and direction of the stress. To address this limitation, elastic modulus‐controlled CPhC films with stress‐responsive mechanochromic behavior are fabricated. While each CPhC film shows the same color change under constant strain, the color change is controlled differently under constant stress. Combining CPhC films prepared with different modulus values enhanced the strain‐responsive mechanochromic sensitivity by ≈25 times. A mechanically heterogeneous weave structure demonstrates a unique biaxial mechanochromic response based on the direction of the stress. These findings suggest that CPhC films can serve as versatile strain/stress sensors that provide visual information about the magnitude and direction of applied stress in multiple dimensions.

Mechanical and Tribological Properties of CrWN/MoN Nano-Multilayer Coatings Deposited by Cathodic Arc Ion Plating

CrWN/MoN nano-multilayer coatings were deposited in pure N2 by multi-arc ion plating using CrW and Mo targets, with the cathode co-controlled by a permanent magnet combined with an electromagnet. The effects of the thickness modulation period on the microstructure and mechanical and tribological performance were systematically analyzed by grazing-incident X-ray diffraction (GIXRD), transmission electron microscopy (TEM), Nanoindentation, scanning electron microscope (SEM) and profilometry using a Talysurf profilometer. The local coherent interfaces and nanoscale modulation period were confirmed by TEM, while the coatings were confirmed to be composed of fcc-CrWN and hexagonal δ-MoN by GIXRD. With the increase in the modulation period, the hardness of the CrWN/MoN nano-multilayer coatings decreased, and the values of the H/E ratio and friction coefficient showed the same variation trend. At an 8.0 nm modulation period, the CrWN/MoN nano-multilayer coating showed the maximum hardness (30.2 GPa), the lowest H/E value (0.082) and an H3/E*2 value of 0.16. With the decrease in the modulation period, the average friction coefficient of the CrWN/MoN nano-multilayer coatings gradually decreased from 0.45 to 0.29, while the wear rate decreased from 4.2 × 10−7 mm3/Nm to 3.3 × 10−7 mm3/Nm.

Machine Learning-Based Figure of Merit Model of SIPOS Modulated Drift Region for U-MOSFET.

This paper presents a machine learning-based figure of merit model for superjunction (SJ) U-MOSFET (SSJ-UMOS) with a modulated drift region utilizing semi-insulating poly-crystalline silicon (SIPOS) pillars. This SJ drift region modulation is achieved through SIPOS pillars beneath the trench gate, focusing on optimizing the tradeoff between breakdown voltage (BV) and specific ON-resistance (RON,sp). This analytical model considers the effects of electric field modulation, charge-coupling, and majority carrier accumulation due to additional SIPOS pillars. Gaussian process regression is employed for the figure of merit (FOM = BV2/RON,sp) prediction and hyperparameter optimization, ensuring a reasonable and accurate model. A methodology is devised to determine the optimal BV-RON,sp tradeoff, surpassing the SJ silicon limit. The paper also delves into a discussion of optimal structural parameters for drift region, oxide thickness, and electric field modulation coefficients within the analytical model. The validity of the proposed model is robustly confirmed through comprehensive verification against TCAD simulation results.

Regulation of Hot Electrons Transport Achieved through Controlled Electron-Phonon Coupling in Metallic Heterostructures.

The electron-phonon (e-ph) interactions are pivotal in shaping the electrical and thermal properties, and in particular, determining the carrier dynamics and transport behaviors in optoelectronic devices. By employing pump-probe spectroscopy and ultrafast microscopy, the consequential role of e-ph coupling strength in the spatiotemporal evolution of hot electrons is elucidated. Thermal transport across the metallic interface is controlled to regulate effective e-ph coupling factor Geff in Au and Au/Cr heterostructure, and their impact on nonequilibrium transport of hot electrons is examined. Via the modulation of buried Cr thickness, a strong correlation between Geff and the diffusive behavior of hot electrons is found. By enhancing Geff through the regulation of thermal transport across interface, there is a significant reduction in e-ph thermalization time, the maximum diffusion length of hot electrons, and lattice heated area which are extracted from the spatiotemporal evolution profiles. Therefore, the increased Geff significantly weakens the diffusion of hot electrons and promotes heat relaxation of electron subsystems in both time and space. These insights propose a robust framework for spatiotemporal investigations of G impact on hot electron diffusion, underscoring its significance in the rational design of advanced optoelectronic devices with high efficiency.

Innovative Strategies for Photons Management on Ultrathin Silicon Solar Cells.

Silicon (Si), the eighth most common element in the known universe by mass and widely applied in the industry of electronics chips and solar cells, rarely emerges as a pure element in the Earth's crust. Optimizing its manufacturing can be crucial in the global challenge of reducing the cost of renewable energy modules and implementing sustainable development goals in the future. In the industry of solar cells, this challenge is stimulating studies of ultrathin Si-based architectures, which are rapidly attracting broad attention. Ultrathin solar cells require up to two orders of magnitude less Si than conventional solar cells, and owning to a flexible nature, they are opening applications in different industries that conventional cells do not yet serve. Despite these attractive factors, a difficulty in ultrathin Si solar cells is overcoming the weak light absorption at near-infrared wavelengths. The primary goal in addressing this problem is scaling up cost-effective and innovative textures for anti-reflection and light-trapping with shallower depth junctions, which can offer similar performances to traditional thick modules. This review provides an overview of this area of research, discussing this field both as science and engineering and highlighting present progress and futureoutlooks.