Fabrication Of Micropatterns Research Articles

Fabrication of Micropatterns on Teflon Surface by Proton Beam Writing and Nitrogen Ion Beam Irradiation

Fabrication of Micropatterns on Teflon Surface by Proton Beam Writing and Nitrogen Ion Beam Irradiation

3D micro patterning on a concave substrate for creating the replica of a cylindrical PDMS stamp

We have developed an alternative soft lithographic method for the fabrication of micro patterns on a concave substrate and fabricated a polydimethylsiloxane (PDMS) cylindrical stamp by utilising a micro patterned concave substrate as a mould. Firstly, we fabricated a flexible PDMS photomask by using two types of self-assembled monolayers to ensure uniform contact between the photomask and the substrate during UV exposure. Next, we fabricated SU-8 micro patterns with a high aspect ratio (greater than 4) on a concave glass substrate using optical soft lithography. We investigated the effectiveness of optical soft lithography on the concave substrate by varying the experimental conditions, including the dimensions and resolutions of patterns. Finally, we fabricated a cylindrical PDMS stamp with converted micro patterns using SU-8 micro patterns as a mould. In addition, we performed rolling micro contact printing and confirmed that micro patterns were successfully transferred to the cylindrical PDMS stamp. Thus, this technique provides us with a novel, quick and easy fabrication technique for 3D micro patterns on curved substrates as well as a cylindrical polymer stamp.

Fabrication of biomolecule-PEG micropattern on titanium surface and its effects on platelet adhesion

Reducing platelet adhesion, controlling platelet distribution and decreasing degree of platelet activation are very important for improving blood compatibility of cardiovascular implants. In this study, the micropattern of heparin and fibronectin mixture (Hep–Fn) embedded within a cell-resistant α-methoxy-poly(ethylene glycol)-ω-succinimidyl carbonate (mPEG-SC) background was fabricated on titanium (Ti) surface. Firstly, the Ti sample was activated by NaOH solution and treated with ethanol solution of (3-aminopropyl)-triethoxysilane (APTE). Secondly, microtransfer molding (μTM) was used to pattern mPEG-SC for resisting protein absorption and platelet adhesion on silanized Ti surface. Finally, Hep–Fn mixture was absorbed on the areas uncovered by mPEG-SC to form a surface for selective adhesion of platelet. Scanning electron microscopy (SEM) showed the surface morphology of the patterned Ti, Fourier transform infrared spectroscopy (FTIR) demonstrated the existence of Hep–Fn and mPEG-SC on the modified Ti surface. The platelet adhesion test was used to evaluate adhesion, activation and distribution of platelets on the bare Ti samples with or without biomolecule micropattern. The results indicated that the patterned samples could effectively reduce platelet adhesion, control platelet distribution and influence platelet activation compared with the non-patterned pure Ti sample. The micropattern sample, P25/10 with a geometry of 25μm mPEG-SC (ridges) and 10μm Hep–Fn (grooves), presented better blood compatibility.

Fabrication of micro patterns using a drawing system with an air-pulse-type dispenser

Fabrication of micro patterns using a drawing system with an air-pulse-type dispenser

Fabrication of 3D Micro Patterns on Concave Substrate and Its Application for the Fabrication of Cylindrical Polymer Stamps

Fabrication of 3D Micro Patterns on Concave Substrate and Its Application for the Fabrication of Cylindrical Polymer Stamps

Metal removal by Acidithiobacillus ferrooxidans through cells and extra-cellular culture supernatant in biomachining

This study explores an innovative metal machining process by using bacteria. Acidithiobacillus ferrooxidans (At. ferrooxidans) was used to remove metal. The bacteria first carried out the oxidation of Fe2+ to Fe3+. The produced Fe3+ then oxidized the metals. The machining of copper, nickel and aluminum was experimentally investigated using both the cells and the culture supernatant of At. ferrooxidans. The material removal rates of these three metals were 2.0, 1.6, 0.55 and 5.5, 4.2 and 0.7mg/hcm2 by using cells and culture supernatant, respectively. Higher metal removal rate was achieved for copper by using the culture supernatant. A microbe-based fabrication of micropattern is thus feasible applying the current principle.

Papillary networks in the dermal–epidermal junction of skin: A biomechanical model

Complex networks of finger-like protrusions characterize the dermal–epidermal junction of human skin. Although formed during the foetal development, such dermal papillae evolve in adulthood, often in response to a pathological condition. The aim of this work is to investigate the emergence of biaxial papillary networks in skin from a mechanical perspective. For this purpose, we define a biomechanical model taking into account the volumetric growth and the microstructural properties of the dermis and the epidermis. A scalar stream function is introduced to generate incompressible transformations, and used to define a variational formulation of the boundary value elastic problem. We demonstrate that incompatible growth of the layers can induce a bifurcation of the elastic stability driving the formation of dermal papillae. Such an interfacial instability is found to depend both on the geometrical constraints and on the mechanical properties of the skin components. The results provide a mechanical interpretation of skin morphogenesis, with possible applications for micropattern fabrication in soft layered materials.

Fabrication of protein micropatterns using a functional substrate with convertible protein-adsorption surface properties

A functional substrate capable of regulating protein adsorption was prepared using a crosslinked albumin (cl-albumin) film for use in the fabrication of protein micropatterns. The adsorption of proteins with different characteristics onto cl-albumin film, including serum proteins, serum albumin, and lysozyme, was investigated using a quartz crystal microbalance. The results showed that surfaces coated with cl-albumin film are highly resistant to protein adsorption, regardless of protein charge and rigidity. In addition, this adsorption-resistance property can be easily converted to promote protein adsorption by exposing the cl-albumin film to a charged polymer solution. By combining the convertible surface property of cl-albumin film and inkjet printing techniques, a precise protein micropattern was successfully fabricated on the substrate. Protein adsorption onto the wall surface of microchannels could also be suppressed or promoted by coating the surface with cl-albumin film. This approach will aid in the development of biomaterials carrying protein micropatterns, such as biosensors, biochips, and cellular scaffolds.

Development of machining technology for micropatterns with large surface area

With increasing demand for micropatterns such as V-shaped microgrooves and the trend of large surface areas in developing technologies, precision machining technology for micropatterns with large surface areas is expected to play an increasingly important role in today's manufacturing technology. In large-surface micromachining, machining time is much longer than that in general pattern machining and it is not easy to achieve uniform machining accuracy in the entire machined areas because of various factors. Therefore, systematic machining processes and technical development for achieving precision in each process are essential prerequisites to reduce the errors. In this study, we focused on developing machining technologies, which include a machine vision system for precise tool setting, an on-machine measurement system for large-area measurement, and software for tool path generation and simulation, for the fabrication of large-surface micropatterns in an electroless nickel-plated workpiece with single-crystal diamond tools and a 32-in., 675 × 450-mm mold with tens of V-and pyramid-shaped micropatterns.

Direct fabrication and morphology of metallic micropatterns by pulsed jet nanoelectrospraying of silver nano-ink

A pulsed jet nanoelectrospray technique was applied to direct fabrication of silver micropatterns. The deposition of a commercial organic silver nano-ink was performed in a fully voltage-controlled fashion by voltage pulses ranging from 550 to 800 V with variable durations. By using 15 μm nozzles, patterns with 100-μm-sized features were locally freeformed on a silicon substrate with a spraying distance of 250 μm. An energy-dispersive X-ray spectrum confirmed metallic silver was developed in all the patterns after heat treatment at 220°C. The size and microstructural evolution of silver films was observed to strongly depend on the deposition volume and material flow over substrate surface. A good linear relationship between the deposition volume and pulse duration was exhibited over the applied voltage range in the cone-jet mode, demonstrating a drop-on-demand capability. By fitting, the deposition volume rate was estimated to be in the range of 0.38–0.59 pL/ms and was shown to increase with the applied voltage.

Nanoscale biomimetics studies of Salvinia molesta for micropattern fabrication

The emerging field of biomimetics allows one to take inspiration from nature and mimic it in order to create various products, devices and structures. There are a large number of objects, including bacteria, plants, land and aquatic animals and seashells, with properties of commercial interest. The subject of interest for this research is the water fern Salvinia molesta because of its ability to trap air. Air-retaining surfaces are of technological interest due to their ability to reduce drag when used for fluid transport, ship coatings and other submersible industrial products in which drag is a concern. The purpose of this research is to mimic the air trapping ability of S. molesta in order to prove that a structure can be created in the lab that can mimic the behavior of the fern as well as demonstrate microfabrication techniques that can be utilized in industry to produce such materials. In this work, a novel methodology for the fabrication of microstructures that mimic the water-pinning and air-trapping ability of S. molesta is introduced. Water contact angle, water roll angle and adhesive force of the new microstructure and water fern are investigated.

Directing Human Chondrocytes Cell Behavior by Fabrication of Protein Micropattern on Polystyrene Surfaces

In the present study, three BMP-2 (bone morphogenetic protein-2) micropatterns were produced on polystyrene (PS) surface by microcontact printing in order to investigate the effect of protein micropattern on biomaterials surface on human chondrocytes behavior. The excellent BMP-2 micropatterns from fluorescent observation were successfully obtained. Cell adhesion and immunohistochemical assay were utilized to explore cell behavior. The results indicated that the protein micropatterns have significant influence on cell adhesion, spread, alignment and protein expression. The cells preferentially adhered on protein micropattern zones. The cells tend to spread towards micropattern direction, leading to better spread. The spread cells could excreted more type II and VI collagen than that of non-spread or poor-spread cells. The results of this paper suggested that extracellular matrix (ECM) protein micropatterns can effectively regulate human chondrocytes behavior, which may be helpful for development of new cartilage tissue.

Computational and experimental studies of electrospray deposition process in pharmaceutical micro-pattern formation

Electrospray deposition on a substrate through a mask is a simple (single-step) yet versatile and robust approach to generate biodegradable polymeric particle patterns. Different methods including photolithography, soft lithography and ink jetting have been employed for automated micro-pattern fabrication; however, most of them are limited to the investigation of material properties of substrates with high-cost and complex procedures. In the present work, two slightly different experimental setups were used to investigate the effect of different operational parameters in electrospray particle deposition on both mask and substrate. The sample consists of an aqueous solution of polymer, solvent and drug. In addition to the experimental section, a mathematical model was developed to track the particle trajectories and focusing effect in electrospray deposition process on the substrate. The final results confirm that the clearest particle pattern and the best focusing effect on the substrate can be achieved with long distance between the nozzle and the substrate, high voltage difference between the nozzle and the mask, short process time and low solution flow rate. On the contrary, a smooth and integrated layer on the mask can be formed with a short distance between the nozzle and substrate in which no clear pattern can be recognized. Furthermore, micro-fibers can be observed on the mask when the voltage difference between the nozzle and substrate is not high.

Fabrication of Micropatterns on Silica Glass by a Room-Temperature Imprinting Method

A nanocomposite was prepared from fumed silica and PVA. Investigation of the morphology of the composite by TEM and electron energy-loss spectroscopy reveals that the nanocomposite consists of homogeneously dispersed SiO2 nanoparticles and PVA. Micropatterns on the nanocomposite were fabricated by room-temperature imprinting. Micropatterned silica glass was obtained by sintering the nanocomposite at 1100°C in air.

Spontaneously reactive plasma polymer micropatterns

A combination of spontaneous reactive chemical domains bounded by non-fouling zones provides a means to covalently immobilize biomolecules in structured, spatially defined arrays. These arrays have application in a wide range of biotechnologies including tissue engineering, proteomics, and diagnostics. In this paper, we describe the fabrication of multi-chemistry micropatterns from plasma polymers. X-ray photoelectron spectroscopy (XPS), together with Time-of-Flight Static Secondary Ion Mass Spectrometry (ToF-SSIMS) and confocal imaging has been utilized to confirm the reactivity and integrity of micropatterns fabricated from amine-reactive maleic anhydride (ppMA) on non-fouling tetraglyme (ppTg). The covalent immobilization of antibodies via the formation of amide linkages with the anhydride groups occurs only in the ppMA domains, while antibody activity is confirmed via their ability to attract specific fluorescent antigens. These micropatterns therefore provide a convenient and effective platform for covalently immobilizing biomolecules in spatially defined areas without the need for multiple step wet chemical immobilization strategies.

Fabrication of micropatterns on the sidewalls of a thermal shape memory polystyrene block

Substrate sidewalls in the current microsystems have not been well used in building devices. On the other hand, the patterns generated on these sidewalls could serve as vertical interconnects or electronic components in 3D circuits. Since existing lithographic approaches could only generate patterns of limited shapes on the sidewalls, a new approach was developed in this work to fabricate various sidewall patterns via strain-recovery deformations of a polystyrene film. The fabrication procedure consisted of three basic steps: first strain recovery, pressing and second strain recovery. The deformations that the polystyrene experienced during the fabrication were first investigated with the help of mm-scaled lines marked on the samples. We found that pressing, instead of lateral stretching, transferred part of side surface of a polystyrene block into part of the top surface, and that the heating after the pressing was capable of transferring the same part of the top surface to the sidewall. The effects of temperature and recovery times on the deformations of the polystyrene were then investigated. We determined how the dimensions of a polystyrene block changed with the temperature. We also examined how many pressing-recovery cycles a polystyrene block could properly experience at 120 °C and 160 °C, respectively. Finally, the developed approach has been applied to generate Ag 50 × 50 µm2 dots, 150 µm wide lines and serpentine-shaped microresistors on both top and side surfaces of polystyrene blocks, followed by the characterization of these products, including shrinking and pressing deformations, surface roughness, wrinkling deformations and resistance changes. We found: (i) the shrinking deformations could be roughly considered as the recovery of the pressing deformations, although the two types of deformations were not identical in magnitudes due to different configurations (i.e. the shrinking deformations were affected by surface patterns, while the pressing deformations were not), and (ii) wrinkles might arise in surface patterns when the polystyrene blocks had large shrinking deformations, which might affect the functionality of the surface patterns and cause, for example, the decrease in their resistances.

Micromold fabrication for flexible display application

Uniform size, height and poreless micropattern fabrication on a flexible substrate becomes an important factor for electronic paper development. Recently, thin and flexible display has been a main target in display industry. Therefore, for the future industrial application, non-petroleum based and environmentally friendly thin and flexible micromold development is an essential technology for flexible display application. For this application, existence of micro or nanopores is drawback due to the reduction of transmittance by light scattering and leak of carrier solvent. The liquid–liquid demixing process made porous structure of the cellulose acetate (CA) film. The resulting CA films were optically turbid due to the light scattering by the pores. Single solvent process provides optically transparent and smooth surface films. Line, honeycomb, and square shapes of photoresist patterns were fabricated on the silicon wafer with different heights (2 μm and 20 μm). The replicas of the CA-patterns have about the same sizes and heights with respect to those of the photoresist patterns. The cross-sectional field emission scanning electron microscope images exhibit the pore-free CA mold.

Research on the technology of femtosecond laser micromachining based on image edge tracing

Aiming at fabrication of complex microstructures and micro-patterns, a kind of femtosecond laser micromachining technology based on the BMP image edge tracing was proposed. We introduced the general principle of this technology and discussed the implementation of the machining paths extraction, optimization, tracing and the feedback of the machining procession in detail. On the basis of this technology, control software for femtosecond laser micromachining was developed. Furthermore, we have accomplished the fabrication of complicated two-dimensional (2D) micro-patterns on a copper thin film. The results indicate that this technology can be used for digital control micromachining of complex patterns or microstructures at micron and submicron scales by femtosecond laser.

Electric field controlled electrospray deposition for precise particle pattern and cell pattern formation

AbstractPhotolithography, soft lithography, and ink jetting have been used for automated micropattern fabrication. However, most of the methods for microfabrication of surface pattern are limited to the investigation of material properties of substrates with high‐cost and complex procedures. In the present study, we show a simple (single‐step) yet versatile and robust approach to generate biodegradable polymeric particle patterns on a substrate using electrospray deposition through a mask. Various particle patterns including patterned dots, circles, squares, and bands can be easily formed and the features of particle patterns could also be tailored using different masks and electrostatic focusing effects. Furthermore, cell patterns can be achieved on the surface of particle patterns by blocking the areas without particle deposition on the substrate and culturing cells on the substrate. Polymeric particle patterns and cell patterns developed in this study could be used in the high throughput screening of sustained release formulations, cell‐based sensing, and drug discovery. In addition to experimental results, an analysis of the associated electric field is used to investigate quantitatively the nature of focusing effect. Scaling analysis is also applied to obtain the dominate terms in electrospray deposition process. © 2010 American Institute of Chemical Engineers AIChE J, 2010

Fabrication of Micropatterns by Laser Direct Writing Using Nanomaterials

Fabrication of Micropatterns by Laser Direct Writing Using Nanomaterials