Imprint Time Research Articles

Simple Isopropanol-Assisted Direct Soft Imprint Lithography for Residue-Free Microstructure Patterning.

A direct soft imprint lithography was proposed to realize the direct fabrication of residue-free, well-shaped functional patterns through a single step. This imprint method requires only a simply prepared isopropanol-treated polydimethylsiloxane (PDMS) stamp without any additional resists. Residue-free Ag patterns were successfully fabricated on different substrates by directly imprinting the Ag ink with the isopropanol-treated PDMS stamp. Furthermore, the coffee-ring effect of the imprinting Ag patterns can be eliminated by optimizing the imprinting time, isopropanol-treating time, and imprinting temperatures. Studies show that the residual Ag ink in the contact region can be absorbed by the isopropanol-treated PDMS stamp due to the "like dissolves like" principle. Finally, this method was employed to fabricate the Ag electrodes for the thin-film transistors, attaining a mobility of ∼8 cm2 V-1 s-1, which is comparable to those with vacuum-processed electrodes. This process provides a simple, low-cost, residue-free, coffee-ring-free, and fast patterning method in the field of microelectronics.

CMOS-compatible electrochemical nanoimprint: High throughput fabrication of ordered microstructures on semiconductor wafer by using a glassy carbon mold

Metal assisted chemical etching (MACE), as an emerging wet chemical etching method for fabricating semiconductor micro/nano-structures (MNS), has attracted wide attentions because of the advantages of simple processes, high accuracy and no damages. However, the conventionally used noble metal catalysts (such as Au, Pt,) trapped in the micro/nano-structures are difficult to be removed or reused, not only harming the electronic performances of the CMOS devices but also increasing the fabrication cost. Here, we propose an electrochemical nanoimprint strategy by using a glassy carbon (GC) imprint mold. To overcome the poor electrocatalytic activity of GC, the GC imprint mold was connected to a Pt sheet in the cathodic chamber. To avoid the contaminations of metal and metallic cations in the fabricated MNS, the cathodic chamber was separated from the anodic one by a proton exchange membrane. By optimizing the technical parameters, including the contact pressure between GC imprint mold and GaAs wafer, the concentration of electron acceptor in the cathodic chamber, the imprinting time, etc., a remarkable corrosion rate of about 130 nm/min was achieved, comparable with that of platinum electrocatalyst. Furthermore, by using a GC imprint mold in the spatially separated corrosion cell, the contaminations caused by both the metal catalysts and metallic ions can be eliminated. Thus, this work provides a potential approach to the high throughput fabrication of CMOS-compatible semiconductor microdevices.

Polarization retention dependence of imprint time within LiNbO3 single-crystal domain wall devices

Ferroelectric LiNbO3 single crystals have wide applications in surface acoustic wave filters, pyroelectric sensors, and electro-optic modulators. Large-area LiNbO3 single-crystal thin films integrated on silicon are promising for high density integration of ferroelectric domain-wall resistance switching memories and transistors. However, the short-time operation of the memory often suffers from poor polarization retention due to the built-in imprint voltage. Here, we observed the strong polarization orientation-dependent imprint effect within either out-of-plane or in-plane LiNbO3 thin-film capacitors. The imprint effect can shift domain switching hysteresis loops toward positive/negative voltages seriously with written negative/positive polarizations that occur within a characteristic imprint time of 5.1 ms–360 s. Once the write time of the memory is shorter than the imprint time, the inverted domain is unstable and switches back into its previous orientation automatically after the termination of a write operation. However, the write failure can be avoided if the write time is longer than the imprint time, and the written domain can be deeply protected by the imprint field. A model of polarization-dependent charge injection at the interface is developed to explain the time-dependent imprint effect. For a mesa-like LiNbO3 memory cell in contact with two side electrodes fabricated at the film surface, the imprint time can be greatly shortened below 30 ns with the extension of one side electrode over the cell surface to screen the tail of the switched domain, enabling ferroelectric domain-wall resistance switching devices in excellent retention and high operation speeds.

High Mannose-Specific Aptamers for Broad-Spectrum Virus Inhibition and Cancer Targeting

High Mannose-Specific Aptamers for Broad-Spectrum Virus Inhibition and Cancer Targeting

PH-Responsive epitope-imprinted magnetic nanoparticles for selective separation and extraction of chlorogenic acid and caffeic acid in traditional Chinese medicines.

Chlorogenic acid and caffeic acid often coexist in traditional Chinese medicines (TCMs) and play roles as antioxidation, antiviral, antitumor and anti-inflammatory agents. Due to their low content and the presence of structural analogues, they cannot be effectively separated by conventional extraction methods. Molecularly imprinted polymers, as synthesized receptors with antibody-like binding properties, have significant advantages in separating structural analogues. However, the harsh imprinting conditions easily induced the degradation of chlorogenic acid. Therefore, caffeic acid was used as an epitope template to replace chlorogenic acid for imprinting. Boronic acid-functionalized magnetic nanoparticles (MNPs) were selected as substrates, which could not only facilitate the immobilization and removal of the templates by pH regulation, but also achieve rapid separation under an external magnetic field. Tetraethyl orthosilicate was selected as an imprinting monomer which allowed for precise control of the thickness of the imprinting layer by adjusting the imprinting time. The prepared epitope-imprinted MNPs showed excellent specificity, in combination with high performance liquid chromatography, have been successfully applied to the selective separation and detection of chlorogenic acid and caffeic acid in TCMs.

Diagnostics of psychological readiness of high school students for research activities in mathematics in the design context of a hybrid intellectual learning environment

Introduction. The problem of improving the process of organizing and supporting the project and research activities of schoolchildren through intelligent management for the purpose of self-organization of the individual, understanding and comprehending complex mathematical knowledge as a principle of personal development is relevant and far from solved. Intelligent systems provide the process of individualization of learning, the establishment of personalized and computerized feedback of cognitive and creative processes. The purpose of the article is to assess the student's readiness for research activities in the context of designing a hybrid intelligent learning environment. Materials and methods. The assessment of the student's psychological readiness for research activities in the conditions of using a hybrid intellectual environment was carried out on an experimental representative sample of students of 1-2 courses of secondary vocational education (n1=42) and students of the senior classes of secondary schools (n2=30). The diagnosis was carried out using the intelligence structure test of R. Amthauer, the creativity questionnaire of D. Johnson, the test "Individual styles of thinking" by A. Alekseev, L. Gromova, the methods of value orientations by M. Rokich, etc. The significance of the differences was established by means of Student's t-test, Fisher's angular transformation, χ2-test. The results of the study. The assessment of psychological readiness for research activities in mathematics was carried out on the basis of the developed nine parameters of scientific potential. The presented results allow us to pre-set the framework of boundary conditions in order to minimize the imprinting time of a hybrid intelligent system (including the selection of the neural network topology). For all three groups of criteria, differences by gender were established, for example, by the parameter "value orientations" (temp = 2.26 > tcr = 2.02); by the parameter "creativity" (χemp2 = 6,02 ≥ χcr2 (0,05;2) = 5,99). And also by the type of educational institution, for example, by the parameter “motivation to achieve the result” (φemp = 0,186 > φcr = 1,64). Conclusion. The results of the research are of practical value, as they serve as a technological basis for establishing the boundaries and boundary conditions of the most significant parameters for the effective realization of scientific potential, expressed in the work of a specialized web interface created with the student's personal account.

The effect of early experiences in barn owl (Tyto alba) behaviour. Acquisition-expression time of neophobia and filial imprinting. Implications for management and conservation

In birds, early experiences determine the later behavioural phenotype of individuals and their way of adapting to the challenges they encounter in their environment. We investigated how the degree of exposure of barn owl chicks to humans and their biological parents influenced their behavioural response to humans and different environments. Only the treatment groups raised by human beings, or those that remained for less time with their biological parents (15 days posthatching), learned to fly towards their trainer. However, the two groups of chicks that were raised the longest by their biological parents (20 and 25 days) never flew towards their trainer. In these last groups, the filial imprint was shown not to be able to be reversed. Neophobia was estimated to emerge between 17 and 19 days of age, as barn owls were able to recognize the environment in which they were habituated, showing fear of a new environment.Birds were able to recognize the person who raised them and objects with which they had been raised. The results obtained in this work can help to establish breeding protocols in this and other species of birds of prey, which improve their adaptability to the environment where they will live, whether in captivity or in the wild.

Laser-assisted thermal imprinting of glass guided mode resonant (GMR) optical filter

Laser-assisted thermal imprinting of glass nanostructures is demonstrated. Compare to the existing thermal imprinting, this method significantly reduced the contact imprinting time. The quality of the replicated glass nanostructures revealed by field emission scanning electron microscope ( SEM) and atomic force microscope ( AFM) exhibited a very smooth surface finish that closely matched the profile of the silicon mold. As proof-of-concept, the utility of laser-assisted, imprinted glass nanostructures as guided-mode resonant (GMR ) optical filter was evaluated. The peak spectral values obtained were satisfactory; which yielded an average FWHM and PWV of 4.6 nm and 691.39 nm respectively.

Minimizing filling time for ultraviolet nanoimprint lithography with templates with multiple structures

Optimizing the locations and sizes of droplets is the key to reducing defects and increasing throughput of ultraviolet nanoimprint lithography. In practice the templates are composed of regions with different structures. The interface between structures will generate complicated fluid flow behavior that will slow the filling time. Here, we explore several strategies through simulations to distribute resist material according to a nonuniform pattern to reduce filling time and ultimately increase throughput. In order to mimic the complexity of a template, the interface between different pairs of template structures is considered and the spreading and merging of droplets are simulated. From these simulations, it is found that the volume and arrangement of droplets underneath strongly affect the imprint time. By distributing the correct amount of resist underneath the template, one can remove the unnecessary fluid transferring step in droplet spreading and reduce the total filling time. Furthermore, by optimally placing the resist droplets, one can delay merging events and accelerate the spreading speed. Finally, the advantage of hexagonal arrangements is explored.

Flexible-templated imprinting for fluorine-free, omniphobic plastics with re-entrant structures

HypothesisCompared to vertical micro-pillars, re-entrant micro-structures exhibited superior omniphobicity for suspending liquids to Cassie-Baxter state. However, the existing re-entrant structures rely on complex multi-step deposition and etching procedures. The conventional, rigid-templated imprinting would instead damage the re-entrant structures. This leads to the question: is it possible to preserve the re-entrant curvatures by a flexible-templated imprinting? ExperimentsWe facilely imprinted the re-entrant structures on a plastic substrate using a flexible nylon-mesh template. The effect of imprinting time (15–35 min), temperature (110–120 °C) and pressure (15–50 Bar) was investigated. To further improve the liquid-repellency and abrasion resistance, the silica nanoparticles (30–650 nm) along with epoxy resin binder (10 mg/mL) were pre-coated. FindingsA one-step imprinting is sufficient to fabricate the re-entrant structures by utilizing flexible nylon-mesh template, without damaging the imprinted structures after the demolding process. The pre-coated silica nanoparticles and epoxy resin (1) improved liquid repellency by introducing hierarchical surface structures (e.g. contact angle hysteresis of olive oil reduced > 10°), and (2) acted as a protective layer against mechanical abrasion (omniphobicity maintained after 25 cycles, ~1.6 kPa sand paper abrasion). Additionally, the fluorine-free post-treatment was sufficient for the omniphobicity on the obtained plastic structures.

Selective extraction of myoglobin from human serum with antibody-biomimetic magnetic nanoparticles

Myoglobin (Mb) is an ideal biochemical marker for the diagnosis of certain diseases caused by damage to heart muscle or skeletal muscle. Nevertheless, serum myoglobin levels are usually very low while the interference components in real sample are extremely abundent. Hence, it is of great clinical significance to establish an effective method for Mb targeting. To obtain desired selectivity, targeting biomolecules like antibody and aptamer are essential to ‘the state of the art’. However, such biomolecules suffer from many disadvantages, such as hard to prepare, susceptible to protease degradation, and high cost. Thus, novel alternatives that can overcome these issues are highly desirable. Herein, we pioneered a template-anchored controllable surface imprinting strategy for selective extraction of Mb from human serum via combining with facile magnetic separation of magnetic nanoparticles (MNPs). Mb-imprinted MNPs, as antibody-biomimetic materials, were prepared using amino group-modified MNPs as substrates and water-soluble self-polymerizable dopamine as imprinting monomer. The optimized imprinting time was 70 min, giving an optimal performance with high practical imprinting efficiency (up to 41%), high imprinting factor (4.2), high binding affinity (Kd=(2.05 ± 0.09) × 10−5 M), as well as excellent recognition selectivity. Moreover, compared to bare MNPs, Mb-imprinted MNPs possessed markedly better pH tolerance. Finally, the selective extraction of Mb from human serum sample by Mb-imprinted MNPs was experimentally confirmed and the recoveries of Mb in spiked serum ranged from (91.12 ± 6.81)% to (107.99 ± 7.76)%, indicating that the Mb-imprinted MNPs could be competent for the selective analysis of Mb in real bio-samples like human serum with high precision and reliability

Impact of Imprint Pressure on Residual Layer Thickness in UV Nanoimprint Lithography

Ultraviolet nanoimprint lithography (UV-NIL) is an important micro/nano fabrication approach. UV-NIL has the advantage of high solution, high throughput and low cost. However, some inner resist flow mechanism is not completely understood by experimental methods. This contribution used the simulation method based on contact mechanics to analyze the impact of imprint pressure on residual layer thickness (RLT). Seven different pressure, from 0.1 MPa to 0.7 MPa, was applied to imprint the same stamp containing grating patterns with various protrusion density. It was found that RLT is not uniform and the areas with high protrusion density has much higher RLT. The average RLT decreases with imprint time and tends to be stable when the imprint process is completed. Both the maximum and minimum RLT decreases with the increase of imprint pressure. These findings can help engineers to design proper stamp pattern distribution and process parameters. Introduction

Investigation on the neighbouring effect of filling micro‐ and nanoscale cavities in ultraviolet nanoimprint lithography

Micro-/nanoscale patterns are popular in many applications, and several techniques to transfer multiscale patterns have been developed. Ultraviolet nanoimprint lithography (UV-NIL) is the most promising method to quickly produce complex structures, and there is a need to understand the resist-flowing and cavity-filling processes because partial cavity filling may cause defects. One crucial element of a stamp is the layout of the multiscale cavities. They can induce some difficulties during the filling process. Five different stamps with various micro-/nanoscale features (one nano feature, one micro feature, one nano feature, and one micro feature, two nano features and one micro feature) were employed in this simulation study. The imprint results show that the neighbouring effect has major issues in the microscale cavity filling and minor issues in the nanoscale. The layout of complex cavities results in poor filling proportions, and longer imprint times and a symmetrical layout were needed to improve the imprint quality. The contact pressure between the stamp and the resist generally declined when the location approached the centre from both sides of the stamp. The overall physical performance of neighbouring micro-/nanoscale cavities was obtained, and this is essential for further understanding and improvements in the UV-NIL process.

Advance in boronate affinity-based controllable orientedsurface imprinting

Biomolecules, like antibody, aptamer and lectin, are still the main force for applications involved in selective separation and recognition. However, these biomolecules are usually suffered from many inevitable problems, such as hard to prepare, high cost, poor stability, as well as limited quantities. Molecular imprinting technique (MIT) as a robust biomimetic molecular recognition strategy to mimic the targeting ability of antibody and enzyme plays a significant role in many areas, including chemical separation, biosensing, catalysis, disease diagnosis, etc. Scientists have pay a lot of attention to developing advanced imprinting approaches to enable MIT adapt many more possible applications. Several user-friendly molecular imprinting methods, such as surface imprinting, epitope imprinting and emulsion imprinting, are hence developed to meet the high analytical requirements. Even so, facile MITs with wide-range versatility and high imprinting efficiency are extremely limited, which restrict the applicability of MIT. Boronate affinity-based controllable oriented surface imprinting (BACOSI) allows for easy and efficient preparation of molecularly imprinted polymers specific to saccharide compounds, which covering glycoproteins, glycopeptides, glycans and monosaccharides. In this paper, the principle, preparation process, applications and recent developments of BACOSI are briefly introduced. Three steps, namely template immobilization, oriented imprinting and template removal, are included in this approach. Template molecules (glycoprotein, glycopeptide, glycan or monosaccharide) immobilized on the surface of boronic-acid-functionalized substrate by virtue of boronate affinity interaction, followed by controllable self-polymerization of biocompatible monomer(s) to form an imprinting layer on the template-anchored substrate with tailored thickness in terms of molecule size of templates, and then the templates are effectively removed under suitable conditions (weak acidic solutions with or without surfactant are often utilized for templates removal). Imprinting in this approach is performed in a precise-controllable manner permitting the thickness of the imprinting layer to be fine-tuned via adjusting the imprinting time. This manner not only simplifies the imprinting procedure but also makes the approach widely applicable to a large range of sugar-containing biomolecules. Most of all, it can provide a guidance for design and preparation of other biomimetic molecular recognition materials, and a new level in methodology of MIT has been promoted by the presentation of this approach. In addition, some issues and future prospects of BACOSI are also presented in this paper based on our previous researches. From the viewpoint of preparation mechanism, template anchoring of BACOSI highly relies on the boronate affinity effect between boronic acid and cis-diol groups, thus it does not work for non- cis-diol -containing compounds. Exploiting some other means for template immobilization or template-anchoring-free imprinting modes is benefit for extending the application scope of BACOSI. Likewise, ideal biocompatibility and the ability of targeting are also significant for biological applications, for instance, cell imaging, clinical diagnosis and therapy. (Nevertheless, available aqueous phase polymerization for BACOSI is very limited, and its non-specific effect is also cannot be ignored when used for clinical analysis. The further study and exploration of imprinting system with negligible non-specific effect and suitable for the biomedical analysis is the key to form practical imprinting technology). In summary, BACOSI strategy just opens the pathway for the research and application based on facile and versatile imprinting technique in the future, there is still a long distance from being ready for use on industrial production and commercialization.

Specific recognition of proteins and peptides via controllable oriented surface imprinting of boronate affinity-anchored epitopes.

Molecularly imprinted polymers (MIPs) are chemically synthesized materials mimicking the recognition of antibodies towards antigens. Epitope imprinting has been an effective strategy, making imprinting of proteins flexible to a great extent. However, so far there is apparently a lack of facile and versatile epitope imprinting approaches. Herein, we present a new method called controllable oriented surface imprinting of boronate affinity-anchored epitopes. In this method, a C-terminus nonapeptide epitope was glycated and anchored as a template onto a boronic acid-functionalized substrate, followed by controllable oriented surface imprinting via the polycondensation of multiple silylating reagents containing functionalities capable of interacting with the epitope. The developed imprinting approach allowed for precise control of the thickness of the imprinting layer through adjusting the imprinting time, generating excellent binding properties. This method was verified to be versatile and efficient. Thus, it could greatly facilitate the preparation of MIPs for specific recognition of proteins and peptides.

Contrivance and Modification of In-house Brinell Hardness Tester for BHN Determination of Soft Materials

The aim of this work was to design and invent Brinell hardness testing machine for in-house testing and used for evaluation of hardness properties of soft materials. In this representation, Coated-Wood-Free (CWF) paper with grammage at 300 grams were used as the sample, whereas, the indenter diameter and the dwell time of imprinting were used at 7.86 mm and 10 seconds, respectively. After that, the hardness values were determined by using the principle of Brinell Hardness Number (BHN). This report presented the mean and the deviation of quantification that measured by this equipment and the focused parameter were included active weight loading, imprinted diameter, and BHN, respectively. Finally, the consequences of this analysis were discussed for development of this apparatus.

In situ Study on the Diffusion Kinetics of Seal Ink by Microinfrared Spectroscopy.

In document examination, it is of great importance to determine the composition of seal ink with different imprint times, and spectroscopic methods are widely used today. In this research, the diffusion of seal inks from three different brands on the same type of paper is monitored insitu by microinfrared spectroscopy and microinfrared imaging technology. The area of the absorption peak at 1743cm-1 gradually decreases with increasing diffusion time. The diffusion kinetics of seal ink on paper are also studied by analyzing the infrared spectra of seal inks at the same measuring point with different diffusion times. The research provides a basic study in understanding the diffusion behavior of seal ink on paper over short time spans.

Transfer durability and fidelity of hard release-agent-free replica mold by repetition of ultraviolet nanoimprint lithography

Ultraviolet nanoimprint lithography provides a high-throughput and cost-effective method to fabricate nanopatterns. However, the master mold deteriorates owing to the adhesion of resin and the occurrence of defects. Prompted by the need to prevent deterioration of the master mold, we developed a new release-agent-free replica mold with high toughness and high hardness. We evaluated the durability, error rate, and fidelity of the transfer patterns of the newly developed release-agent-free replica molds of hard pillar- and hole-shaped patterns. As a result, the developed replica mold with pillar-shaped patterns exposed to UV radiation at 50J/cm2 has the best release properties, and the replica mold with hole-shaped patterns can transfer up to 7000 imprint times under the same conditions.

Preparation of molecularly imprinted polymers specific to glycoproteins, glycans and monosaccharides via boronate affinity controllable-oriented surface imprinting.

Molecularly imprinted polymers (MIPs) are materials that are designed to be receptors for a template molecule (e.g., a protein). They are made by polymerizing the polymerizable reagents in the presence of the template; when the template is removed, the material can be used for many applications that would traditionally use antibodies. Thus, MIPs are biomimetic of antibodies and in this capacity have found wide applications, such as sensing, separation and diagnosis. However, many imprinting approaches are uncontrollable, and facile imprinting approaches widely applicable to a large variety of templates remain limited. We developed an approach called boronate affinity controllable-oriented surface imprinting, which allows for easy and efficient preparation of MIPs specific to glycoproteins, glycans and monosaccharides. This approach relies on immobilization of a template (glycoprotein, glycan or monosaccharide) on a boronic-acid-functionalized substrate through boronate affinity interaction, followed by self-polymerization of biocompatible monomer(s) to form an imprinting layer on the substrate with appropriate thickness. Imprinting in this approach is performed in a controllable manner, permitting the thickness of the imprinting layer to be fine-tuned according to the molecular size of the template by adjusting the imprinting time. This not only simplifies the imprinting procedure but also makes the approach widely applicable to a large range of sugar-containing biomolecules. MIPs prepared by this approach exhibit excellent binding properties and can be applied to complex real samples. The MIPs prepared by this protocol have been used in affinity separation, disease diagnosis and bioimaging. The entire protocol, including preparation, property characterization and performance evaluation, takes ∼3-8 d, depending on the type of substrate and template used.

Various Types of Lipases Immobilized on Dendrimer-Functionalized Magnetic Nanocomposite and Application in Biodiesel Preparation

Three sub-group lipases of Burkholderia cepacia lipase (BCL), Rhizomucor miehei lipase (RML), and Candida rugosa lipase (CRL) were covalently immobilized on dendrimer functionalized magnetic carbon nanotube and used as catalysts to catalyze biodiesel production. The effects of imprinting molecule, organic solvent, water, methanol, temperature and time interval of methanol addition on the yield of biodiesel were optimized. The results showed that bioimprinting could greatly enhance catalytic performances of the three immobilized lipases. The obtained lipases were then employed to catalyze biodiesel production, and the achieved optimum conditions were: for BCL, water content 5 wt. %, reaction temperature 35°C, and with t-butanol as reaction medium, methanol : oil molar ratio 4:1, its highest biodiesel yield attained 96.4%; for RML, water content 10 wt. %, reaction temperature 50 °C, n-octane as the reaction medium, methanol : oil molar ratio of 5:1, the utmost biodiesel conversion rate was up to 96.2%; and ...