Embossing Technique Research Articles

Influence of Distribution Size of Micro Energy Director Array on Ultrasonic Precise Sealing of Polymer MEMS Device

In order to improve the quality and precision of ultrasonic precision sealing of polymer MEMS device, micro energy director array was proposed on the sealing surface of polymer MEMS device, the influence of the distribution size of micro energy director array to ultrasonic precise sealing was studied. Based on the experiment of PMMA micro-pipe sealing, five kinds of micro energy directors with different distribution sizes were made on the sealing surface by hot embossing technique. The method of ultrasonic precise sealing based on efficiency’s feedback was used and the influence of micro energy director array’s distribution size on the quality of ultrasonic sealing was summarized through the observation on the rule of wetting behavior of micro energy director array.

Self-healing liquid metal composite for reconfigurable and recyclable soft electronics

Soft electronics and robotics are in increasing demand for diverse applications. However, soft devices typically lack rigid enclosures which can increase their susceptibility to damage and lead to failure and premature disposal. This creates a need for soft and stretchable functional materials with resilient and regenerative properties. Here we show a liquid metal-elastomer-plasticizer composite for soft electronics with robust circuitry that is self-healing, reconfigurable, and ultimately recyclable. This is achieved through an embossing technique for on-demand formation of conductive liquid metal networks which can be reprocessed to rewire or completely recycle the soft electronic composite. These skin-like electronics stretch to 1200% strain with minimal change in electrical resistance, sustain numerous damage events under load without losing electrical conductivity, and are recycled to generate new devices at the end of life. These soft composites with adaptive liquid metal microstructures can find broad use for soft electronics and robotics with improved lifetime and recyclability.

Grating-coupled surface-plasmon fluorescence DNA sensor

Genetic analysis is considered to be the ultimate diagnostic approach in many fields, e.g., in medicine for disease detection, in agricultural technology for food and feed authentication, in forensics, to name a few. Consequently, great interest is growing in developing sensitive and reliable analytical tools (biosensors) to identify whole DNA sequences, oligonucleotide fragments, or single-nucleotide polymorphisms (SNPs). In addition, these biosensors are becoming vital tools for clinical diagnosis and point-of-care systems. They need to be of high sensitivity, high specificity, fast response, inexpensive, and easy to use. In this work, we discuss a surface-plasmon fluorescence grating coupler-based biosensor, fabricated on polymer substrates, and with a designed surface binding procedure that offers the direct response required for a sensor to be implemented in a disposable system. These gratings fabricated on polymer substrates using an embossing technique showed excellent and reproducible resonance coupling results. We also present a monitoring protocol for hybridization reactions based on fluorescence resonance energy transfer (FRET) to quench the bulk solution contribution that decreases the sensitivity of the grating biosensors.

Integration of alumina-phosphate glass with cobalt-doped magnesium aluminate structure using a hot embossing technique for microlaser development.

In this work, the technique of hot embossing has been applied for the bonding of alumina-phosphate (PAL) glass with cobalt-doped magnesium aluminate (MALO) crystals. The application of the hot embossing technique for bonding of PAL/MALO is a competitive method, as compared to the existing thermobonding techniques. The obtained PAL/MALO interfaces show high quality, similar to what is currently achievable with other, more expensive traditional methods. The interfaces of the bonded samples have been successfully tested for strength and damage thresholds. The damage threshold is estimated to be around 4.5-7.9kW/cm2. Therefore, microlasers can be developed based on the obtained components.

Structuring of solution processed and thermally evaporated As33S67 thin films by soft stamp hot embossing method

Chalcogenide As33S67 vitreous thin films prepared by thermal evaporation and spin-coating method from n-propylamine and n-hexylamine based solutions were structured using hot embossing technique with soft polydimethylsiloxane (PDMS) stamps. The influence of deposition method and conditions as well as thermal history of the samples was studied. Obtained results gave evidence that solution processed thin films can be structured at significantly lower temperatures in comparison with thermally evaporated thin films, even below Tg of the glass. Theory explaining observed phenomena based on the structural differences of solution processed and thermally evaporated thin films was proposed. Notable decrease in required embossing temperature of solution processed thin films will widen the range of chalcogenide glass compositions that can be structured by soft stamp hot embossing as well as the pool of usable substrates (such as substrates with lower temperature stability).

Evaluation of Warpage and Residual Stress of Precision Glass Micro-Optics Heated by Carbide-Bonded Graphene Coating in Hot Embossing Process.

A newly developed hot embossing technique which uses the localized rapid heating of a thin carbide-bonded graphene (CBG) coating, greatly reduces the energy consumption and promotes the fabrication efficiency. However, because of the non-isothermal heat transfer process, significant geometric deviation and residual stress could be introduced. In this paper, we successfully facilitate the CBG-heating-based hot embossing into the fabrication of microlens array on inorganic glass N-BK7 substrate, where the forming temperature is as high as 800 °C. The embossed microlens array has high replication fidelity, but an obvious geometric warpage along the glass substrate also arises. Thermo-mechanical coupled finite element modelling of the embossing process is conducted and verified by the experimental results. Based on trial and error simulations, an appropriate compensation curvature is determined and adopted to modify the geometrical design of the silicon wafer mold. The warpage of the re-embossed microlens array is significantly decreased using the compensated mold, which demonstrates the feasibility of the simulation-oriented compensation scheme. Our work would contribute to improving the quality of optics embossed by this innovative CBG-heating-based hot embossing technique.

Hot embossing of aspherical Fresnel microlenses: design, process, and characterization

Hot embossing is a technique used to fabricate high-precision and high-quality polymeric components that combines low costs with high aspect ratio fidelity replication. In this study, we manufactured two aspherical Fresnel molds employing the single-point diamond turning process on an electrolytic copper workpiece, one with 10 μm constant height 30 zones and the other with 250 μm constant width 40 zones. The micromachined mold reproduced PMMA convex-plane lens optical quality replicas through the micro hot embossing technique. We used a scanning electron microscope (SEM), spectrophotometry, and non-contact optical profilometer to evaluate the replication fidelity qualitatively: the lens mold and the fine three-dimensional microstructures on the PMMA substrate surfaces. The results of the surface finish of the diamond machined mold sample are in the range of 4.92 nm (areal average surface roughness Sa) and 6.04 nm (areal root-mean-squared roughness Sq), respectively, and the values for the replicas being 4.73 nm and 5.94 nm, respectively. The results demonstrated that the geometry form accuracy obtained of the microfeatures was at the submicron level with little viscoelastic recovery. The surface roughness in the nanometer level got successfully replicated.

Hot Embossing of Micro-Pyramids into Thermoset Thiol-Ene Film.

This paper presents the first attempt to texturize a fully crosslinked thermoset shape memory polymer using a hot embossing technique. UV-cured thiol-ene films were successfully embossed with anisotropically-etched Si (100) stamps at a temperature of 100 °C, which is about 50 °C above the glass transition temperature of the polymer. The low storage modulus of the polymer in a rubbery state allowed us to permanently emboss random micro-pyramidal patterns onto the surface of the film with high fidelity by applying 30 MPa pressure for 1 h. Atomic force microscopy (AFM) investigation showed perfect replication of the stamp micropattern with typical height of the largest inverted pyramids close to 0.7 µm and lateral dimensions in the range of 1–2 µm. Changes in surface roughness parameters of the embossed thiol-ene films after annealing them at 100 °C for 1 h or storing for 2 months in air at standard room conditions were negligible. The achieved results open new perspectives for the simple and inexpensive hot embossing technique to be applied for the micropatterning of prepolymerized thermoset shape memory films as an alternative to micropatterning using UV casting.

Fabrication and Characterization of Curved Compound Eyes Based on Multifocal Microlenses.

Curved compound eyes have generated great interest owing to the wide field of view but the application of devices is hindered for the lack of proper detectors. One-lens curved compound eyes with multi-focal microlenses provide a solution for wide field imaging integrated in a commercial photo-detector. However, it is still a challenge for manufacturing this kind of compound eye. In this paper, a rapid and accurate method is proposed by a combination of photolithography, hot embossing, soft photolithography, and gas-assisted deformation techniques. Microlens arrays with different focal lengths were firstly obtained on a polymer, and then the planar structure was converted to the curved surface. A total of 581 compound eyes with diameters ranging from 152.8 µm to 240.9 µm were successfully obtained on one curved surface within a few hours, and the field of view of the compound eyes exceeded 108°. To verify the characteristics of the fabricated compound eyes, morphology deviation was measured by a probe profile and a scanning electron microscope. The optical performance and imaging capability were also tested and analyzed. As a result, the ommatidia made up of microlenses showed not only high accuracy in morphology, but also imaging uniformity on a focal plane. This flexible massive fabrication of compound eyes indicates great potential for miniaturized imaging systems.

Hot Embossing Process Technology Forming Arbitrary Patterns in Real Time

AbstractWith the development of mobile sensors and biosensors, an ultrafine process technology that can generate ultrafine patterns and has mass production capability has garnered attention recently. Unlike the existing hot embossing techniques, the impact print‐type hot embossing process can generate a microscale pattern that has arbitrary pattern width and depth on a polymer film in real time using a single impact header. For this reason, this process can be applied to various industrial fields that require ultrafine patterns. However, it cannot create intricate patterns due to the limitations of the two‐axis stage control system. Furthermore, its application to a mass production that requires pattern repetition is limited because of the single header system. In this paper, a three‐axis impact print‐type hot embossing system using a multiheader and two algorithms, the impacting coordinate‐based data extraction algorithm and independent driving algorithm, to overcome the limitations of previous systems is proposed. Thanks to the multiheader and control algorithm, this process can generate repetitive patterns in real time, and it can adjust the pattern resolution by controlling the pattern extraction interval. The proposed method is thus expected to be widely applicable to industrial fields that require microscale user‐defined patterns such as mobile sensors and biosensors.

PDMS‐based hot embossing method of fabricating SU‐8 photoresist conical nozzle for inkjet print‐head

This work reports a PDMS-based hot embossing technique. The proposed method enables rapid, low-cost and mass-produced fabrication of SU-8 photoresist conical nozzle for inkjet print-head with soft PDMS moulds. The hydrophobic time for SU-8 master mould treated by trimethyldichlorosilane (TMCS) was determined. And the optimised thickness of SU-8 photoresist before hot embossing was 58.5 ± 1.55 μm corresponding to 3750 r/min of spin coating speed. The imprinting parameters were investigated. The highest replication precision was obtained in the embossed SU-8 conical nozzle processed by an embossing pressure of 2.57 MPa, an embossing temperature of 80°C, and an embossing time of 6 min. Finally, this work presents the fabrication of the SU-8 conical nozzle plate with the large aperture of 40.01 ± 1.24 μm, small aperture of 27.12 ± 1.07 μm, and the nozzle height of 50 ± 1.26 μm.

Influence of the Fabrication Accuracy of Hot-Embossed PCL Scaffolds on Cell Growths.

Polycaprolactone (PCL) is a biocompatible and biodegradable polymer widely used for the realization of 3D scaffold for tissue engineering applications. The hot embossing technique (HE) allows the obtainment of PCL scaffolds with a regular array of micro pillars on their surface. The main drawback affecting this kind of micro fabrication process is that such structural superficial details can be damaged when detaching the replica from the mold. Therefore, the present study has focused on the optimization of the HE processes through the development of an analytical model for the prediction of the demolding force as a function of temperature. This model allowed calculating the minimum demolding force to obtain regular micropillars without defects. We demonstrated that the results obtained by the analytical model agree with the experimental data. To address the importance of controlling accurately the fabricated microstructures, we seeded on the PCL scaffolds human stromal cell line (HS-5) and monocytic leukemia cell line (THP-1) to evaluate how the presence of regular or deformed pillars affect cells viability. In vitro viability results, scanning electron and fluorescence microscope imaging analysis show that the HS-5 preferentially grows on regular microstructured surfaces, while the THP-1 on irregular microstructured ones.

Novel approach to decrease sheet thinning during sheet metal forming by using embossing technique

Embossing technique allows strengthening properties of sheet metal materials to be specifically increased. This increase in strength results from strain hardening and residual stresses, which are induced into the sheet metal material during the embossing process and thus locally influence mechanical properties such as yield and tensile strength. As a result, not only the final properties of sheet metal components can be modified, but also the formability of semi-finished sheet metal products can be influenced. Concretely, the local strengthening can significantly improve the force transmission in sheet metals during deep drawing and thus enlarge the process window. In the FEM study presented in this paper, dual-phase DP600 grade steel sheets having a thickness of 1.2 mm were subjected to near-surface unilateral embossing. Subsequently, these embossed steel sheets were used to investigate the influence of different embossing patterns and embossing depths on the critical areas appearing during deep drawn of a cylindrical cup. In order to evaluate the effects of the focused embossing parameters on the forming behavior, Nakajima tests were additionally performed with embossed sheet specimens. An essential finding of this study is that the local increase in yield strength contributes to preventing premature sheet thinning in the force transmission zones and avoid split formation in early stages of a deep drawing process.

Bosporus. Polychromic Styles of the Late Roman Period

The polychromic style of the Late Roman period is characterized by a combination of the following traits: a stable set of ornamental motifs, specific ornamentation techniques (embossing, stamping, granulating and filigree techniques) and bezel setting of semi-precious stones or jewelry glasses. Altogether, five stylistically distinct groups of polychromic articles can be distinguished in the Late Roman Period. The first stylistic group named Illerup–Kerch consists of objects decorated with thin gold plates embossed with the following designs: granulation, filigree patterns, concentric circles and serpents. They appear as early as the second third of the 3rd century AD and continue to exist up to the middle of the 4th century. The second stylistic group Berkasovo–Kishpek includes objects decorated mainly with thin gilded silver plates embossed with both the same and some new designs such as sidelong crosses, stars, triangles. These objects appear not earlier than the early 4th century and continue to exist during most of this century. The third stylistic group Gorgippia–Loo includes massive gold objects decorated all over with festoon patterns of soldered granulation and filigree, and with turquoise, carnelian and garnet inserts in the center of the girdle. While such objects are particularly common at the Caucasian sites (Armaziskhevi, Kldeeti, Loo) dated to the second half of the 2nd century and the first half of the 3rd century, they are also known in Bosporus (Gorgippia, Panticapaeum) and in the Kuban region (“Golden cemetery”). In addition, some of the Late Roman sites have yielded rare finds of objects executed in a technique similar to the technique of filigree incrustation. These objects constitute the fourth stylistic group Aragvispiri–Tanais. They were found at Komarov II (barrow 8); Adzhimushkai, 1841; burial with the Golden Mask of 1837; Berdyansk barrow; Tanais, 1972, etc. The fifth group Messaksudi–Kerch appears in the second third of the 4th century AD and combines characteristics of the previous two groups: ornaments of the third group (genuine granulation and filigree), but on thin gold plates. The main ornamental motif are granulated triangles which fill all the space between the bezels inserted with semiprecious stones and glasses. Nearly all items included in the third and fifth groups may have analogies among the objects of I.P. Zasetskaya’s stylistic group I of the Hunnic era polychrome products, but precede them and belong to the 3rd – 4th centuries AD.

Carbide-bonded graphene-based Joule heating for embossing fine microstructures on optical glass

This paper reports the fabrication of high-quality microstructures on optical glass via hot embossing using carbide-bonded graphene (CBG) based Joule heating for the first time. In this study, a tailor-made micro hot embossing tool equipped with a modified CBG-based Joule heating system was designed and developed for transferring microstructures (e.g., microlens arrays, MLAs for short) from the CBG-coated silicon mold insert into the optical glass (P-SK57). Initially, the surface topographies of a typical 3 × 3 MLA from a bare silicon mold to an embossed glass replica were compared for evaluating form errors brought in during different preparation stages. The feasibility of the CBG-based Joule heating technique for the non-equilibrium thermal imprinting of optical glass was evaluated by the surface integrity and replication fidelity of the embossed MLA features. Thermally induced residual stress and imaging performance of the embossed glass lens were assessed as well. Experimental results indicate that the proposed CBG-assisted hot embossing technique, in combination with single point diamond turning technology, has the capability of producing high-quality glass MLAs. Moreover, this technique allows notably fine replication of surface shapes at the microscale, as well as roughness information at the nanoscale. Consequently, the embossed MLA replica shows satisfactory imaging performance.

A Wearable Sensory Textile‐Based Clutch with High Blocking Force

A sensory textile‐based clutch (STBC) activated by vacuum is presented. The STBC is an assembly of two inextensible webbings equipped with 2.3 mm wide rigid bumps fabricated directly on them by a hot embossing technique, and two elastic bands, all air sealed by a silicone elastomer cover. While, in passive mode, the clutch provides low resistance to elongation, upon vacuum, the specular rigid bumps interlock and provide a high withstanding force. The embedded capacitive‐based transducer allows encoding the clutch's elongation, with a position resolution reaching 1.15 mm, owing to a real‐time processing algorithm. The STBC (140 mm × 30 mm × 8 mm) sustains up to 419 N force with an activation pressure of −0.5 atm. The small size of the rigid components and a priming strategy (keeping the pressure at −0.01 atm in disengaged mode) enable response times down to 14 ms for a 115 N blocking force. A preliminary demonstration of a fully worn device shows the potential of the STBC approach for enabling the control of the engagement and disengagement of blocking forces, as well as monitoring of typical parameters of human movement such as knee bending angles, for future developments of light and efficient unpowered exoskeletons.

ПРИЖИЗНЕННЫЙ ПОРТРЕТ ИВАНА ГРОЗНОГО: ВИЗУАЛИЗАЦИЯ УГАСШЕГО ПАМЯТНИКА ЕСТЕСТВЕННОНАУЧНЫМИ МЕТОДАМИ

The collections of the State Historical Museum keep a single offering copy of the first-printed Apostle 1564 by Ivan Fedorov with the image of the tsar Ivan the Terrible. This portrait was made in the embossing technique on the cover of the binding and is now almost completely extinct. This extinguished image was investigated using multispectral macro photography and subsequent computer processing. It has allowed visualizing the tsar portrait. This image is the only lifetime portrait of the most famous ruler of Russia, which survived to our time. Embossing specifics on the cover of the binding suggests the use of engraving on metal for the manufacture of this image. This is one of the first example of this technique in Russia. The features of the portrait and the embossing of both covers of the binding corresponded to the Western European standards for the design of an elite book, which came to Russia along with typography. The portrait of the king on the chest of a heraldic eagle accompanied by his titles served as a representation of the royal status of Ivan IV, that had been recognized by the Oriental patriarchs for three years before. A review of the existing portraits of Ivan the Terrible led to the conclusion that the resulting image was the only lifetime portrait of the king, which has close correspondences with the reconstruction of his face on the skull, made by M. M. Gerasimov. The history of the existence of a royal copy of Apostol of 1564 from the moment of its creation to the present day is reconstructed in the article.

Tunable Silver Nanoparticle Arrays by Hot Embossing and Sputter Deposition for Surface-Enhanced Raman Scattering

Surface-enhanced Raman scattering (SERS) spectroscopy has attracted a lot of attention over the past 30 years. Due to its extreme sensitivity and label-free detection capability, it has shown great potential in areas such as analytical chemistry, biochemistry, and environmental science. However, the major challenge is to manufacture large-scale highly SERS active substrates with high controllability, good reproducibility, and low cost. In this study, we report a novel method to fabricate uniform silver nanoparticle arrays with tunable particle sizes and interparticle gaps. Using hot embossing and sputtering techniques, we were able to batch produce the silver nanoparticle arrays SERS active substrate with consistent quality and low cost. We showed that the proposed SERS active substrate has good uniformity and high reproducibility. Experimental results show that the SERS enhancement factor is affected by silver nanoparticles size and interparticle gaps. Furthermore, the enhancement factor of the SERS signal obtained from Rhodamine 6G (R6G) probe molecules was as high as 1.12 × 107. Therefore, the developed method is very promising for use in many SERS applications.

Modeling, analysis and effective improvement of aluminum bowl embossing process through robot simulation tools

Abstract This paper discusses the development of an automated loading and unloading system for aluminum bowl embossing operation on a power press machine. Presently the operation under consideration is manual. The worker manually picks the bowl from the input bin and places it onto a press bed for stamp embossing and after completion, removes the embossed bowl and places it into an output bin. Compared to conventional embossing techniques, bowl embossing includes fewer manufacturing steps and is therefore likely to be better suited for automated production. Automation of the bowl embossing production step is a crucial task in order to lower the manufacturing costs of these aluminum bowls. For studying manual loading/unloading conditions of the worker, a detailed Time and Motion analysis of worker is carried out. On the basis of cycle time analysis results, an alternative to the manual operation, a more sophisticated automated loading/ unloading system is suggested. The viability of the suggested system is checked through simulation and cycle time analysis. A proposed system which uses a robotic manipulator and a feeding system is also developed and tested. The software used for analysis, CAD model development and simulation is Delmia V6. A real case study belonging to aluminum bowls manufacturing scenario is simulated and its embossing process is used as a reference in this paper. From this example, it is shown that considerable production cycle time and manufacturing cost savings can be anticipated compared to manual loading/unloading. The suggested automation method is very flexible. It can be used for the production of aluminum bowls embossed with different shapes, sizes, and with different embossing patterns.

Fabrication of 3D nano-hemispherical cavity array plasmonic substrate for SERS applications

Surface-enhanced Raman scattering (SERS) have numerous applications in areas such as analytical chemistry, biochemistry, and environmental science. However to manufacture SERS active substrates with good reproducibility and low cost is not easy, which hinder the SERS technology from being widespread in various applications. In this study, we developed a batch producible hot embossing 3D nanostructured SERS substrate technology for SERS applications. This study utilized the anodic aluminum oxide (AAO) self-assembled uniform nano-hemispherical array barrier layer as a template to create a durable nanostructured nickel mold. With the hot embossing technique and the durable nanostructured nickel mold, we were able to batch produce the 3D Nanostructured SERS chip with consistent quality and low cost. In addition, according to the SERS experiments, the 3D nano-hemispherical cavity array combined with sub-10-nm-gaps Au NPs showed distinct SERS signals in both Rhodamine 6G and Chlorpyrifos measurements. Therefore, the developed method is good to be used extensively in rapid chemical and biomolecular detection applications.