Fabrication Of Substrates Research Articles

ABSTRACT Technologies currently employed for land-based seaweed cultivation are cost-intensive and wasteful of resources. Hence, the present study examined natural and synthetic materials as growth substrates for a sustainable on-land production of Ulva spp. In total, 16 materials were qualitatively evaluated regarding their usability represented as availability, durability, reusability, and adherence, as well as growth of algae on the selected materials. The results of spore adhesion and mobility indicated that loofah sponge, clay pellets, and polyurethane foam were most suitable for algal adhesion. Synthetic materials generally exhibited low toxicity and high durability but low usability, as algal spores clogged the materials. In contrast, natural materials exhibited increased vulnerability to mechanical stress, leading to reduced durability and low reusability. Furthermore, toxic effects that might have inhibited movement and attachment of spores were more likely to occur from natural materials due to degradation processes during the tests.

Flexible pressure sensors are essential for wearable electronics, human–machine interfaces, and soft robotics. However, conventional Polydimethylsiloxane (PDMS)-based sensors often suffer from limited conductivity, poor filler dispersion, and low structural integration with textile substrates. In this work, we present a robotic drop-coating approach for fabricating graphite–copper nanoparticle (G-CuNP)/PDMS composite pressure sensors with textile-integrated electrodes. By precisely controlling droplet deposition, a three-layer sandwiched structure was realized that ensures uniformity and scalability while avoiding the drawbacks of conventional full-line coating. The effects of filler loading and graphite nanoparticle (GNP) and copper nanoparticle (CuNP) ratios were systematically investigated, and the optimized sensor was obtained at 40 wt% total fillers with a graphite content of 55 wt%. The fabricated device exhibited high sensitivity in the low-pressure region, stable performance in the medium- and high-pressure ranges, and an exponential saturation fitting with R2 = 0.998. The average hysteresis was 7.42%, with excellent cyclic stability over 1000 loading cycles. Furthermore, a hand-shaped sensor matrix composed of five distributed sensing units successfully distinguished grasping behaviors of lightweight and heavyweight objects, demonstrating multipoint force mapping capability. This study highlights the advantages of robotic drop-coating for scalable fabrication and provides a promising pathway toward low-cost, reliable, and wearable soft pressure sensors.

A facile, efficient, and cost-effective strategy for fabricating a bowl array SERS (surface-enhanced Raman scattering) substrate is presented. The resulting substrate is dimensionally compatible with micrometer-sized microplastics and integrates both SERS enhancement and light-trapping effects, enabling highly sensitive detection of micrometer-sized microplastics. Initially, a pillar array template was produced via UV lithography, followed by UV imprinting to replicate bowl arrays with a diameter of 50 μm, a depth of 25 μm, and a periodicity of 100 μm. A gold layer was subsequently deposited, followed by the modification of its surface with AgNPs to construct the SERS substrate. The experimental results reveal that the optimal enhancement was achieved at an AgNP suspension concentration of 15 mg/mL. The substrate exhibited a detection limit of 10−9 M for rhodamine 6G with an enhancement factor (EF) of 2.02 × 107 and successfully detected polyethylene (PE) microplastics of 5, 10, and 20 μm at concentrations down to 100 μg/mL, demonstrating outstanding sensing performance.

Surface-enhanced Raman scattering (SERS) has emerged as a powerful analytical tool for ultrasensitive trace molecule detection. Herein, we report the fabrication of uniform nanofilm substrates composed of Au–Ag alloy hollow nanoparticles (HNPs) with tunable sizes, demonstrating exceptional performance as SERS platforms. Using crystal violet (CV) as a Raman probe, the substrates exhibit densely and uniformly distributed “hot spots” across the nanofilm surface, enabling a detection limit as low as 10[Formula: see text] M for CV with excellent signal reproducibility (relative standard deviation, RSD [Formula: see text] 6.61%). Notably, the substrates achieve quantitative detection of thiram pesticides at ultratrace concentrations (0.01 ppb). Finite-difference time-domain (FDTD) simulations elucidate that the observed SERS enhancement originates from the synergistic contribution of two factors: (1) the localized surface plasmon resonance (LSPR) effects mediated by the Au–Ag HNPs and (2) the formation of abundant, spatially homogeneous “hot spots” within the nanofilm architecture. This study highlights the potential of size-engineered Au–Ag HNP nanofilms as robust, and high-performance SERS substrates for environmental and analytical applications.

Developing polymer networks with high modulus and antiscratch properties is a long‐lasting challenge due to the fundamental conflicts underlying conventional design principles. Especially on soft substrates, polymer coatings with programable multifunctionality, including high hardness, antiscratch, and waterproofing, are ubiquitous application requirements but much more challenging to achieve. Here, scratch‐resistant, stiffening, and waterproof fabrics are fabricated via in situ deposition of a fluorinated polymer (FP) and polyacrylate (PAcr) network. The binary gradient network is achieved via the surface segregation of the FP in a two‐bath pad–dry–cure process with waterproof finishing, followed by a stiffening finishing sequence. The stiffening value reaches 58.6, and the contact angle achieves 140°. Due to the tribological characteristics of the fluorine‐containing polymer and the formation of a binary gradient polymer network, the ΔL of the finished fabric reduced to 1.1 while the ΔL for the stiffened fabric is 4.1, revealing the scratch endurance. The strategy of establishing fluorine‐induced lubricious coating proposed in this article achieves a balance between antistarch and stiffening on soft fabric substrates, which paves the way for solving the long‐lasting, unsolved, and crucial challenge in the textile industry.

An eco-friendly, sustainable approach for pre-surface modification of various textile substrates using locally produced fungal lipase from Aspergillus niger HANAN-EGY strain, followed by post-functional finishing using vanillin and/or zinc oxide nanoparticles (ZnONPs) as green functional additives, citric acid/sodium hypophosphite (CA, SHP) as ester-crosslinking agent, and the pad-dry-microwave fixation technique was developed. The imparted antibacterial, anti-UV, and aroma fragrance release functional properties, along with the change in %N of wool containing fabrics, loss in weight, as well as the surface roughness, were evaluated. SEM and EDX analyses were also performed on selected finished fabric samples. The data so obtained demonstrated that the extent of pre-surface modification and subsequent multifunctionalization is governed by the lipase dose, type of substrate, as well as kind and concentration of functional additive. The adoption and implementation of the suggested environmentally sound strategy results in the production of green, sustainable, antimicrobial, anti-UV, and fragrance-releasing textiles. On the other hand, the produced fungal lipase could be used to remove oil stains.

The increasing demand for decentralized, accessible, and rapid analytical tools is driving a transformation in healthcare toward point-of-care (POC) analytical technologies. The final aim is to reduce the cost of healthcare management originating from frequent patient hospitalizations and expensive and time-consuming laboratory-based analyses. This review explores the integration of microfluidic technologies with electrochemical sensing platforms, aiming to address the urgent need for POC analytical platforms. Owing to the miniaturization of fluid management systems and exploiting fluid automation, microfluidic devices enable low sample consumption, cost-effective analysis, and multiplexed detection, offering promising tools for real-time health monitoring. Among the other materials, the most commonly used substrates for microfluidics fabrication are paper, PDMS, and adhesive tape, which support custom-designed microchannel architectures, passive fluid motion, and wearable integration. Special attention is given to wearable sensors for sweat analysis, with various approaches employing capillary-driven flows and smart microfluidic designs to enable continuous and autonomous monitoring of biomarkers. Highlighting relevant works from the last 5 years, the review explores the role of integrated microfluidic electrochemical sensing devices in delivering advanced decentralized analytical platforms, with significant potential for clinical use in biomarker detection.

Surface-enhanced Raman spectroscopy (SERS) enables ultra-sensitive molecular detection and has broad analytical and biomedical applications; recent advances focus on high-performance substrates and innovative detection strategies. However, achieving controllable and reproducible substrate fabrication—particularly using natural templates such as hair—remains challenging, limiting SERS application in trace analysis and on-site detection. This study developed a single-hair in situ SERS platform using a natural hair template. Confinement within hair cuticle grooves and capillary-evaporation assembly enables dense arrangement of cetyltrimethylammonium bromide-coated Au nanorods and polyvinylpyrrolidone-coated Au nanoparticles, forming uniform plasmonic nanoarrays. Spectroscopy and microscopy analyses confirmed the regular alignment of nanostructures along the hair axis with denser packing at the edges. The platform detected crystal violet at 10−9 M, yielding clear signals, negligible background, and stable peaks after repeated washing. For p-phenylenediamine, enhancement was observed down to 10−6 M. On the platform, a concentration-dependent response appeared within 10−3–10−5 M, with spatial Raman imaging along the hair axis. Capillary-evaporation coupling and interfacial wettability facilitated solute enrichment from larger to smaller gap hotspots, improving signal-to-noise ratio and reproducibility. This portable, low-cost, and scalable method supports rapid on-site screening in complex matrixes, offering a general strategy for hotspot engineering and programmable assembly on natural templates.

Cellulose nanofibrils (CNFs) have emerged as sustainable alternatives to single-use plastics due to their favorable barrier properties; however, their inherent hydrophilic properties limit their efficacy as water barriers. In this work, we present a novel approach using a CNF matrix and fungal mycelia to grow coatings directly onto a range of paper and textile substrates to enhance their liquid water resistance via a sustainable, low-energy process. We demonstrate that CNF-based mycelial coatings exhibit a water contact angle (CA) of 139.1° ± 3.5° and a water uptake of 29.6 g m-2 ± 3.5 g m-2 after 3 days of growth, compared to a CA of 27.2° ± 5.0° and a water uptake value of 80.0 g m-2 ± 12.8 g m-2 for a CNF coating alone. Furthermore, the CNF-based coating still retained excellent oil and grease barrier properties (Kit Test of 12), air permeability, and oxygen transmission rates even after at least 3 days of mycelial growth. Comparing CNFs and pulp as a matrix for the coating, we find that CNF facilitates faster growth, a higher maximum CA, and a lower water uptake than pulp. Finally, we demonstrate that both the hyphal structure and surface hydrophobicity are playing a role in water barrier functionality by comparing the grown mycelial coating to a coating of fungal hydrophobic surface proteins─hydrophobins─alone. Collectively, our work demonstrates that growing CNF-based mycelial coatings onto paper or textile substrates offers a potentially scalable solution to create water-resistant barriers on diverse substrates, creating more sustainable alternatives to single-use plastics.

Nano-sized ZnO particles on fabric substrates: Achieving ultra-flexible, self-healing UV photodetectors with superior anti-distortion performance

Superhydrophobic-photothermal-insulating synergistic CNT/COF composite coatings for solar-powered crude oil restoration.

Breaking free from PFAS: biocompatible, durable and high-performance octenyl succinic anhydride (OSA)-modified starch/chitosan coating with ZnO for textile applications.

Enhanced compatibilization of waste commingled plastics for high-quality cultivation substrate fabrication through biodegradable ingredients modulation

Thin silicon wafer fabrication is a crucial aspect of semiconductor manufacturing, offering enhanced material yield and reduced fabrication costs. Traditional techniques for producing thin silicon substrates often involve the use of supporting substrates for bonding/debonding or intricate processes, such as etching and thinning. In this study, we present the fabrication of an ultrathin polycrystalline silicon substrate utilizing a melt-spinner approach. Our approach has yielded a substrate of unprecedented dimensions, characterized by a width of 1 cm, a length of 5 cm, and an approximate thickness of 20 μm, and fabricated at a speed of 35 m s-1. This development marks a significant progression in the domain of silicon substrate fabrication, as it stands as the thinnest free-standing polycrystalline silicon substrate achieved to date. Our approach presents substantial potential for cost-effective substrate manufacturing, eliminating the need for the current thinning and etching steps that contribute to material waste, excessive processing time, and high electricity consumption for melting raw silicon material as melt-spun silicon substrates require a postprocessing step of polishing for less than 10 min. This advancement is poised to benefit not only silicon photovoltaic applications but also a broad range of applications, including lightweight wearable electronics, ultrathin membrane structures, microelectromechanical systems for sensing, and the development of advanced material processing.

Flexible capacitive fabric pressure sensors, owing to their natural compatibility with textile substrates, high sensitivity, and low power consumption, have emerged as pivotal components in constructing smart textiles. However, achieving concurrently low cost, high performance, and broad applicability remains a persistent challenge for their future development. Key research directions include the development of novel sensing mechanisms, integration of advanced functional nanomaterials, and innovative fabrication processes for flexible devices. This review summarizes recent advancements in flexible capacitive fabric pressure sensors. Beginning with the sensing mechanism, it systematically examines the material selection for electrode and dielectric layers, as well as fabrication techniques. Finally, future application prospects are discussed.

Perovskite-based thin-film field effect transistors (PeFETs) have yet to achieve the full theoretical potential of this promising class of materials. To bridge this gap, it is essential to develop and optimize novel perovskite compositions and fabrication techniques. Given the large variety of potential compounds as well as the manifold of influencing variables such as concentration, temperature, and choice of solvent, a high-throughput research approach is critical for efficient exploration and advancement. We present a flexible and customizable process that spans from substrate fabrication to device characterization. This process is enabled by and integrates photolithography for custom patterning, an automated measurement station for FET characterization, and automated data analysis. The automated measurement station is based on a multiplexer, which is connected to five measurement boards. The measurement boards are configured to measure one substrate with four devices each. Allowing the automated measurement of 20 devices with up to 5 different perovskite formulations. Using standardized testing procedures, the raw data is automatically analyzed to get the transfer and output characteristics of the PeFETs as well as key performance parameters like the threshold voltage, subthreshold swing, and the field effect mobility. The result is a systematically organized data pool with easily comparable data for different perovskite compositions or modifications in fabrication conditions.

A novel Artificial Magnetic Conductor (AMC) backed, wearable, wide-band monopole antenna is designed for the investigation of path gain at the entire 5 GHz Wireless Fidelity (Wi-Fi) band. To confirm the flexibility and user comfort requirement, the monopole and the AMC structure are printed on a textile denim substrate. The integrated wearable antenna with AMC was fabricated using a laser cutting technology and occupies a dimension of 0.66λ × 0.66λ × 0.10λ mm3 (λ is calculated at a resonant frequency of 5.2 GHz). For the evaluation of path gain, the simulation and measured transmission coefficient (S21) data were collected over distances of 1000 mm for free space and on-body. Furthermore, the simulation and measured results prove that the performance of the antenna is dynamic to the lossy human body and structural deformation at the entire band of operation. Additionally, experimental analysis was successfully carried out by pouring water on the antenna to test its performance in wet conditions.

As the demand for edge platforms in artificial intelligence increases, including mobile devices and security applications, the surge in data influx into edge devices often triggers interference and suboptimal decision-making. There is a pressing need for solutions emphasizing low power consumption and cost-effectiveness. In-sensor computing systems employing memristors face challenges in optimizing energy efficiency and streamlining manufacturing due to the necessity for multiple physical processing components. Here, we introduce low-power organic optoelectronic memristors with synergistic optical and mV-level electrical tunable operation for a dynamic “control-on-demand” architecture. Integrating signal sensing, featuring, and processing within the same memristors enables the realization of each in-sensor analogue reservoir computing module, and minimizes circuit integration complexity. The system achieves 97.15% fingerprint recognition accuracy while maintaining a minimal reservoir size and ultra-low energy consumption. Furthermore, we leverage wafer-scale solution techniques and flexible substrates for optimal memristor fabrication. By centralizing core functionalities on the same in-sensor platform, we propose a resilient and adaptable framework for energy-efficient and economical edge computing.

Mechanotransduction plays a pivotal role in shaping cellular behavior including migration, differentiation, and proliferation. To investigate this mechanism more accurately further, this study came up with a novel elastomeric substrate with a stiffness gradient using a sugar-based replica molding technique combined with a two-layer PDMS system. The efficient water solubility of candy allows easy release, creating a smooth substrate. By adjusting the substrate's thickness, the optimal effective gradient length for the study is achievable. Additionally, adjusting substrate thickness precisely controls stiffness, from very soft to hard-tissue-like rigidity. Atomic force microscopy characterization confirmed a continuous stiffness gradient on three commonly used PDMS mixtures, 1:30, 1:50, and 1:75, demonstrating the versatility of this method for fabricating and tuning substrates to mimic various tissue environments. In cellular experiments, 3T3 fibroblast cells exhibited a significant migratory response toward the 1:50/1:75 two-layer stiffness gradient, with cells migrating preferably in stiffer directions. Its cost-effectiveness, smooth surface, and ability to regulate gradient substrates with varied stiffness via different PDMS combinations are key advantages. By precisely replicating physiologically relevant mechanical microenvironments, this method advances mechanobiology research and facilitates modeling of stiffness-guided cellular behaviors, paving the way for reliable tissue engineering and regenerative medicine studies.

Fabrication of paper-based SERS substrates for detecting trace MG molecules in complex samples