Embossing Technique Research Articles

Hot Embossing to Fabricate Parylene-Based Microstructures and Its Impact on the Material Properties.

This study aims to establish and optimize a process for the fabrication of 3D microstructures of the biocompatible polymer Parylene C using hot embossing techniques. The different process parameters such as embossing temperature, embossing force, demolding temperature and speed, and the usage of a release agent were optimized, utilizing adhesive micropillars as a use case. To enhance compatibility with conventional semiconductor fabrication techniques, hot embossing of Parylene C was adapted from conventional stainless steel substrates to silicon chip platforms. Furthermore, this adaptation included an investigation of the effects of the hot embossing process on metal layers embedded in the Parylene C, ensuring compatibility with the ultra-thin Parylene printed circuit board (PCB) demonstrated previously. To evaluate the produced microstructures, a combination of characterization methods was employed, including light microscopy (LM) and scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR). These methods provided comprehensive insights into the morphological, chemical, and structural properties of the embossed Parylene C. Considering the improved results compared to existing patterning techniques for Parylene C like plasma etching or laser ablation, the developed hot embossing approach yields a superior structural integrity, characterized by increased feature resolution and enhanced sidewall smoothness. These advancements render the method particularly suitable for diverse applications, including but not limited to, sensor optical components, adhesive interfaces for medical wearables, and microfluidic systems.

Patterned Photonic Actuators with Dynamic Shape‐Morphing and Color‐Changing Capabilities Fabricated by Athermal Embossing Technology

AbstractStimuli‐responsive patterned photonic actuators, characterized by their patterned nano/microscale structures and capacity to demonstrate synergistic color changes and shape morphing in response to external stimuli, have attracted intense scientific attention. However, traditional patterned photonic actuator systems still face limitations such as cumbersome and time‐consuming preparation processes and small‐scale deformations. Herein, we introduce a facile approach involving an athermal embossing technique to rapidly fabricate patterned photonic actuators based on near‐infrared (NIR) light‐responsive liquid crystal elastomers. The resulting patterned photonic actuators demonstrate remarkable features, including brilliant angle‐dependent structural color, complex three‐dimensional actuation, and good color durability under NIR light stimulation. As illustrative demonstrations of the proof‐of‐concept, we fabricate two light‐fuelled patterned photonic soft actuators: a butterfly‐inspired actuator that can produce wing‐flapping dynamic changes in structural color, and an origami crane‐shaped actuator with shape memory, structural color information storage, and dynamic display properties. This strategy provides distinct insights into the design and fabrication of various patterned photonic soft robotic devices and intelligent actuators.

Patterned Photonic Actuators with Dynamic Shape-Morphing and Color-Changing Capabilities Fabricated by Athermal Embossing Technology.

Stimuli-responsive patterned photonic actuators, characterized by their patterned nano/microscale structures and capacity to demonstrate synergistic color changes and shape morphing in response to external stimuli, have attracted intense scientific attention. However, traditional patterned photonic actuator systems still face limitations such as cumbersome and time-consuming preparation processes and small-scale deformations. Herein, we introduce a facile approach involving an athermal embossing technique to rapidly fabricate patterned photonic actuators based on near-infrared (NIR) light-responsive liquid crystal elastomers. The resulting patterned photonic actuators demonstrate remarkable features, including brilliant angle-dependent structural color, complex three-dimensional actuation, and good color durability under NIR light stimulation. As illustrative demonstrations of the proof-of-concept, we fabricate two light-fuelled patterned photonic soft actuators: a butterfly-inspired actuator that can produce wing-flapping dynamic changes in structural color, and an origami crane-shaped actuator with shape memory, structural color information storage, and dynamic display properties. This strategy provides distinct insights into the design and fabrication of various patterned photonic soft robotic devices and intelligent actuators.

Investigate the Effect of Coating Concentration and Coating Thickness on the Anti-microbial Properties of Polycarbonate Sheet

This paper investigates the effect of coating concentration (ppm), and coating thickness (µm) on the anti-microbial properties of polycarbonate sheets using a variety of anti-microbial agents (Cu-infused Mg(OH)2, Mg(OH)2, Cu(OH)2, MgO, CuCl2.2H2O, and ZnO). In addition, a complete analysis was performed for all agents to rank the best agent in terms of the highest anti-microbial performance against E. coli K-12 MG1655 in two time intervals (4 and 24 hours). The coating concentration (ppm) was found to be a significant factor in the anti-microbial characteristics for Cu-infused Mg(OH)2, Mg(OH)2, Cu(OH)2, MgO, CuCl2.2H2O, and ZnO (p = 0.004, p < 0.0001, p < 0.0001, p = 0.0297, p = 0.0011, and p = 0.0130 respectively). The coating thickness (µm), on the other hand, was found to be a major contributor to the anti-microbial properties of Cu-infused Mg(OH)2, Mg(OH)2, Cu(OH)2, MgO, and CuCl2.2H2O (p < 0.0001, p = 0.0004, p = 0.0011, p = 0.0310, and p < 0.0001 respectively). The analysis determined that the coating did not influence the anti-microbial properties of ZnO. The interaction between the coating concentration (ppm), and the coating thickness (µm) was found to be a significant factor for Cu-infused Mg(OH)2, Cu(OH)2, MgO, CuCl2.2H2O, and ZnO (p < 0.0001, p = 0.0001, p = 0.0004, p < 0.0001, and p < 0.0001 respectively), however, this was not a significant factor for Mg(OH)2. Highlights • The anti-microbial activity of the inorganic material is dependent on the particle shape and size. • Particles with sharp edges will provide additional physical injuries to the microorganisms. • Smaller particle size will provide higher surface area therefore better interaction with microorganisms. • The coating concentration and coating thickness will be crucial to the anti-microbial activity. • The thermal embossing techniques demonstrate good adhesion to the surface.

Enhancing light output of WSLED with microlens array fabricated on Tb³⁺/Sm³⁺ co-doped fluorophosphate glass via hot embossing

In this study, Tb3+/Sm3+ co-doped NaPO3–BaF2–AlF3–CaF2 glasses were synthesized using the melt quenching method. These glasses exhibit a glass transition temperature below 380 °C and maintain optical transparency close to 90% within the visible spectrum. Furthermore, under UV excitation, the emission shows a wide spectrum and varies with the rare-earth doping ratio or excitation wavelength. Hence, this glass was introduced into the wide-spectrum light-emitting diode (WSLED) application. Moreover, a microlens array was fabricated on the glass surface using the hot embossing technique. In fact, the microlens array enhanced the light output power of the WSLED by 5% at a driving current of 150 mA.

Microfabrication of Thermoplastic Polypropylene Surface Structures via Thermal Imprinting for Controlling the Adhesion of Easy Peel Package.

Micropatterns were fabricated on polypropylene (PP) surfaces using the hot embossing technique with various temperatures ranging from 160 to 175 °C and applying force conditions from 100 to 300 N. To evaluate the replication quality, an effective filling ratio of 1 indicates that the volume of the formed pattern is similar to the mold cavity volume. From the results, the filling ratio increased with increasing the embossing temperature. For instance, under a constant force of 100 N, the filling ratio of polypropylene (PP) with small square arrays (pattern SS) increased from 0.08 to 0.41 when the embossing temperature was raised from 160 to 175 °C, respectively. With the increase of applied force, the filling ratio also increased. At an imprinting temperature of 175 °C and an applied force of 300 N, the highest effective filling ratio that was achieved was approximately 0.99. Furthermore, the effect of PP with different melt flow indexes (MFIs) on the filling ratio was investigated. For food packaging applications, a micropatterned PP sheet was heat-sealed with a biaxially oriented polypropylene (BOPP) film. The micropatterned PP sheet demonstrated easy-opening properties by varying sealing contact areas and micropattern geometries between the sheet and the BOPP film. All micropatterned PP sheets with an MFI of 25 g/10 min exhibited an easy peel property with adhesive failure characteristics at a heat-sealing temperature of 150 °C and a dwell time of 3 s. There was no residue on the PP substrate surface. The overall findings are beneficial in understanding the hot embossing technology for fabricating micropatterns on polymer surfaces, and it can be applied in an easy peel property for packaging applications.

Low-Loss Plasmonics with Nanostructured Potassium and Sodium-Potassium Liquid Alloys.

Alkali metals have low optical losses in the visible to near-infrared (NIR) compared with noble metals. However, their high reactivity prohibits the exploration of their optical properties. Recently sodium (Na) has been experimentally demonstrated as a low-loss plasmonic material. Here we report on a thermo-assisted nanoscale embossing (TANE) technique for fabricating plasmonic nanostructures from pure potassium (K) and NaK liquid alloys. We show high-quality-factor resonances from K as narrow as 15 nm in the NIR, which we attribute to the high material quality and low optical loss. We further demonstrate liquid Na-K plasmonics by exploiting the Na-K eutectic phase diagram. Our study expands the material library for alkali metal plasmonics and liquid plasmonics, potentially enabling a range of new material platforms for active metamaterials and photonic devices.

Fabrication of low-cost MEMS microfluidic devices using metal embossing technique on glass for lab-on-chip applications

This paper discusses a low-cost technology for the fabrication of microfluidic devices on glass substrate using metal embossing technique. The fabrication technique demonstrated is a much simpler approach of embossing on glass using thermo-compression process with a patterned metal layer to define device structure. Well established printed circuit board fabrication photo-process is used to realize the desired planar geometry on metal layer deposited over a glass substrate. The depth of the channel is defined by the thickness of the metal deposited by electro-plating. The embossing technology offers a relatively safer approach conducive to batch processing to enable repeatable, high-yield, low-cost devices fabricated using low-cost equipment. Major challenges of achieving adhesion of the deposited thick nickel layer without peel-off and control of the thermo-compression process to achieve reliable and repeatable embossing without structural distortions were addressed. To prove its suitability for manufacturing, experiments were carried out with full wafer of 6″ × 6″ square glass wafer and optimal process steps for low-cost microfluidic device manufacturing have been well established.

P22 Fabrication methodologies for antimicrobial polypropylene surfaces with leachable and non-leachable antimicrobial agents

Abstract Objectives Develop a methodology for the fabrication of antimicrobial polypropylene (PP) surfaces with (i) leachable copper (II) chloride dihydrate (CuCl2·2H2O) and (ii) non-leachable magnesium hydroxide (Mg (OH)2) biocides. Methods and results Two methodologies are used to develop antimicrobial PP surfaces. One method involves melt blending and subsequent injection moulding, where the biocide additives were compounded with PP and subsequently injection moulded. The other method involves the thermal embossing of antimicrobial agents on the surface of a PP substrate. The obtained biocide-bearing PP surfaces were evaluated against Escherichia coli K-12 MG1655 for 0, 4 and 24 h to evaluate their antimicrobial properties. The injection-moulded PP bearing 5% CuCl2·2H2O showed a 6-log reduction of E. coli K-12 MG1655 after 24 h, while only 1 log reduction was observed for PP bearing 5% Mg (OH)2. The thermally embossed PP surfaces bearing CuCl2·2H2O and Mg (OH)2 particles (at a concentration of 10 mg/mL) showed 3 log and 4 log reduction, respectively, against E. coli K-12 MG1655 after 24 h. Conclusions The results clearly demonstrate that CuCl2·2H2O conferred antimicrobial properties to PP surfaces that were prepared by both injection moulding and thermal embossing approaches owing to the presence of leachable copper ions. In contrast, the non-leachable Mg (OH)2 imparted antimicrobial properties only to the surface prepared via the thermal embossing technique. Significance and impact Plastics with leachable biocides are effective antimicrobial surfaces, but their toxicity is a major concern. This study provides a fabrication methodology for non-leachable PP-based antimicrobial surfaces that are potentially safer. In addition, this strategy can be extended to many other plastic substrates.

Multiplexed detection of biomarkers using a microfluidic chip integrated with mass-producible micropillar array electrodes

Quantifying multiple biomarkers with high sensitivity in tiny biological samples is essential to meet the growing demand for point-of-care testing. This paper reports the development of a novel microfluidic device integrated with mass-producible micropillar array electrodes (μAEs) for multiple biomarker detections. The μAE are mass-fabricated by soft lithography and hot embossing technique. Pt–Pd bimetallic nanoclusters (BNC) are modified on the surface of μAEs by constant potential (CP)/multi-potential step (MPS) electrodeposition strategies to improve the electroanalytical performance. The experimental result displays that Pt–Pd BNC/μAEs have good sensitivity enhancement compared with bare planar electrodes and bare μAEs, the enhancement being 56.5 and 9.5 times respectively, from the results of the H2O2 detection. Furthermore, glucose, uric acid and sarcosine were used as model biomarkers to show the biosensing capability with high sensitivity. The linear range and LOD of the glucose, uric acid and sarcosine detection are 0.1 mM–12 mM, 10 μM–800 μM and 2.5 μM–100 μM, 58.5, 3.4 and 0.4 μM, respectively. In particular, biosensing chips show wide linear ranges covering required detection ranges of glucose, uric acid and sarcosine in human serum, indicating the developed device has great potential in self-health management and clinical requirements.

An enhanced triboelectric nanogenerator with micro-grid patterned PDMS for self-powered sensing and music playback

In latest years, TENGs are used in a wide range of fields. However, the low output performance of TENGs prevents them from continuously supplying power to devices, which motivates us to reduce this limitation. Currently, several studies have been conducted to improve the output performance of TENG by increasing the specific surface area of friction materials through plasma treatment, photolithography, and other methods. Yet the common methods are too cumbersome and expensive. In this work, we proposed a triboelectric nanogenerator with micro-grid patterned PDMS(X-TENG) using a metal woven test sieve as a mold and a modified thermal embossing technique, which is low-cost, easy-to-make, mass-produced. The micro-grid pattern is roughly square and the side lengths d of the pattern is 5000 μm, 500 μm, 50 μm, and 5 μm, respectively. As d gradually decreases, the specific surface area SS increases, the charge density on the surface (σ) increases, moreover, the performance is improved. When d is 5 μm, X-TENG has the optimal capability with 1.5 times the short-circuit current and 2.3 times the open-circuit voltage of a TENG composed of smooth PDMS film (S-TENG). In addition, X-TENG serves as a self-powered sensing to monitor human health for application. X-TENG also acts as a self-powered control device, which implements the state change of the Linux-based Raspberry Pi 4B pressurized music player. Hence, the X-TENG holds great promise for intelligent sensing and self-powered supply.

Embossing of silicon with an ultrashort laser pulse diffracted by a bubble in liquid

Laser-assisted nanostructuring of silicon interfaces provides a unique procedure for leading-edge technologies. We report on a new embossing technique with tightly focused Gaussian-shaped ultrashort laser pulses near the ablation threshold in liquid. We take advantage of a primary microbubble for controllable spatial-modulation of light intensity of succeeding pulses. Such a bubble, generated in liquid near the molten silicon surface by the first pulse, serves as an obstacle for the second pulse following with a sub-millisecond time delay, to produce a diffraction ring pattern. Variation of laser intensity can be utilized to guide the diffraction patterns. Thus the various annular patterns deeply embossed up to hundreds nanometers on the surface are produced with high reproducibility. Morphology of modified surface layer is investigated in detail using atomic-force microscopy, as well as scanning and transmission electron microscopies. Full-wave EM modeling of laser beam diffraction by the bubbles with various radii and shapes shows that the peak intensity in silicon is up to 1.7 times higher than in bubble-free liquid. Atomistic simulation of ultrafast heating with such a diffraction peak reveals that an annular microdimple surrounded by rims is formed by high-gradient pressure in molten silicon to be frozen after several nanoseconds.

Enhanced mechanical properties and improving wetting ability of polypropylene/cassava pulp composites

Natural cassava pulp was selected as a bio-based reinforcement in plastic polymer composites to enhance mechanical and wetting properties as an eco-friendly product. This study developed reinforced polypropylene (PP) composites with cassava pulp (CP) to improve mechanical properties and wetting ability. The PP/CP specimens were fabricated via twin screw extrusion and injection molding. Tensile and flexural testing were performed using a universal testing machine, with wetting properties characterized by a contact angle goniometer. Incorporation of 10 wt% cassava pulp showed enhanced tensile strength (4.85%), Young’s modulus (14.38%) and flexural modulus (23.30%) compared with neat polypropylene, indicating higher stiffness of natural fiber-filled composites. Micropatterns were formed on the composite surfaces using the hot embossing technique. A superhydrophobic surface was achieved by designing micropattern geometry. Water contact angle of micropatterned neat polypropylene and polypropylene/cassava pulp composites increased compared to material with no pattern. Micropatterns on PP/CP composite surfaces can be used to develop new functional materials with high mechanical and superhydrophobic properties.

Optically tunable metal-dielectric diffractive structures

Hybrid metal-polymer micropillar arrays are elaborated by solvent-assisted embossing techniques and subsequent gold deposition. The polymer is poly(methyl methacrylate) (PMMA) grafted with Disperse Red 1 (DR1) azobenzene derivatives. This photochromic material exhibits spectacular photomechanical properties. Under off-normal $p$-polarized illumination in the absorption band of the DR1, the metal-polymer hybrid micropillars bend in a direction determined by the light polarization. The deformation remains stable when the light excitation is turned off. The optically driven modification of the pillar shape allows us to tune the optical properties of the pillar arrays. Very large intensity changes are measured in the diffraction spectra at zero order (specular reflection), first order, and second order, with almost on and off switching of the diffraction efficiency. The photoinduced bending of the micropillars can be fully reversed by switching the linear light polarization to the orthogonal $s$-polarization state. This allows us to restore the initial optical properties of the pillar array. The polarization-controlled reversibility of the pillar deformation suggests a complex photoinduced deformation mechanism involving stress and stress release assisted by the change in the viscoelastic properties of the polymer under illumination in the absorption band of the DR1 chromophore.

Mid-infrared ZBLAN glass optical components made by hot embossing technique

We demonstrate the successful development of refractive lenses made of ZBLAN fluoride glass using the hot embossing technique. Synthesized in-house ZrF4-BaF2-LaF3-AlF3-NaF glass is thermally stable and has high transmission in the range of 0.4–8.0 µm. A lens was formed with a brass stamp inside a resistant furnace under standard atmosphere conditions. No mechanical or chemical postprocessing is used to obtain the optical quality of the lens surface. As a proof-of-concept, we have developed plano-convex lenses with a diameter of 10 mm and f#=3. The tested lenses have good imaging properties with a resolution of 23 pl/mm and 8 pl/mm for 1.5 µm laser and broadband thermal source emitting in the mid-infrared range, respectively.

A Co-Printed Nanoslit Surface Plasmon Resonance Structure in Microfluidic Device for LMP-1 Detection.

This paper reports a novel micro/nanostructure co-hot embossing technique. Gold-capped nanostructures were used as localized surface plasmon resonance (SPR) sensors and were integrated into a microfluidic channel. The advantage of the co-hot embossing technique is that the SPR sensors do not need to be aligned with the microfluidic channel while bonding to it. The integrated SPR sensor and microfluidic channel were first characterized, and the sensitivity of the SPR sensor to the refractive index was found using different concentrations of glycerol solutions. The SPR sensor was also used to quantify latent membrane protein (LMP-1) when modifying anti-LMP-1 at the surface of the SPR sensor. Different concentrations of LMP-1 samples were used to build a calibration curve.

Large-scale hot embossing of 1 µm high-aspect-ratio textures on ABS polymer

Hot embossing is the most promising method for surface micropatterning of low-value-added products made of cheap polymers such as acrylonitrile butadiene styrene (ABS). In hot embossing, a polymeric part is compressed with a micropatterned mold at a temperature slightly above the glass transition temperature (Tg), held at this temperature for some time, and then cooled below Tg for demolding. However, through this study, we demonstrate that using this conventional strategy to replicate 1 µm structures on a large area on ABS results in defective replicas or damaged molds. We propose a viscous embossing strategy, wherein the polymer is embossed far above its Tg and demolded shortly thereafter in the viscous state. The absence of cooling is the key for damage-less demolding of 1 µm structures on a large area. Yet, an excessive increase of the temperature and time results in the formation of a thermally-induced tensile skin on the polymer surface, as evidenced by the experimental and theoretical analyses performed in this study. In this study, 100 million 1–6 µm wide high-aspect-ratio (1–4) holes were embossed on a smartphone-sized area on the ABS polymer in a few seconds. This proposed strategy exhibits several advantages such as highly precise and more productive replication, which are not observed in the conventional hot embossing technique.

A simple electrochemical immunosensor based on a gold nanoparticle monolayer electrode for neutrophil gelatinase-associated lipocalin detection

An electrochemical immunosensor for the accurate detection of cat neutrophil gelatinase-associated lipocalin (NGAL) in urine samples based on an electrode with a monolayer of gold nanoparticles (AuNPs) was proposed in this study. To fabricate the sensing electrode, a nickel mold with concave micron hemisphere array was prepared and then used to transfer the micron hemispherical structure onto a polyethylene terephthalate (PET) film using the hot embossing technique. A gold thin film was sputtered onto the micron hemispherical structure array, after which 1,6-hexanedithol and AuNPs were uniformly deposited on the PET membrane to form a sensing electrode. The NGAL concentrations were measured by electrochemical impedance spectroscopy after attaching the anti-NGAL. Results revealed that the proposed sensing scheme exhibited a wide dynamic detection range from 1 to 100 ng/mL, which is far enough to distinguish the healthy (NGAL concentration <10 ng/mL) from the damaged kidney. A low limit of detection and high sensitivity of 0.47 ng/mL and 10261.8 Ω ng−1mL, respectively, were also measured. After performing real sample detection using urine samples from cats collected at a veterinary hospital, the results confirmed that the proposed NGAL detection approach in this research could accurately detect the concentration of NGAL in cat urine samples.

СЕРЕБРЯНЫЙ ОКЛАД ЕВАНГЕЛИЯ ИЗ СОЛЬВЫЧЕГОДСКОГО БЛАГОВЕЩЕНСКОГО СОБОРА И АНАЛОГИЧНЫЕ ПРОИЗВЕДЕНИЯ СТРОГАНОВСКИХ МАСТЕРОВ

The article examines the silver oklad of the Holy Gospel from the Moscow Kremlin Museums, made by using the embossing technique (basma). This oklad was previously dated from mid to late 16 th century and attributed to silversmiths of the Russian North. Based on a comprehensive study of this work and similar items it was proved that this piece was made by Stroganov craftsmen at the beginning of the 17th century, on the instructions of Nikita Stroganov, as a contribution to the Solvychegodsk Cathedral of the Annunciation. This attribu- tion is confirmed by archival documents. The form and decoration of the silver Gospel oklad, created in Solvychegodsk by order of Nikita Stroganov, copied the best creations of Moscow silversmiths, but the Stroganov works in silver, while similar to those in Moscow, have their own special features and originality.

Measurement and Analysis of Optical Properties of Polymer Films with Triangular Pyramid Optical Functional Texture

A poly (vinyl chloride) film with triangular pyramid array structure was designed and fabricated. In this paper, a plane to plane hot embossing technique is used to fabricate a triangular pyramid antireflection film on the surface of single crystal silicon solar cells. By testing the optical properties of optical functional textured films, it is found that the reflectivity of triangular pyramid textured films obtained by hot embossing is significantly lower than that of smooth flat films; The absorption and antireflection of high light on the film surface are obvious; The photoelectric conversion efficiency of the solar cell is further improved. Triangular pyramid optical functional structure has great potential in improving the performance of silicon solar cells, which can be applied to different types of solar cells. These improvements are of great significance to the commercialization of silicon solar cell devices.