1,721,578 research outputs found
VIBRATION CONTROL OF A LAMINATED PLATE WITH PIEZOELECTRIC SENSOR/ACTUATOR : ACTIVE AND PASSIVE CONTROL METHODS
No full text11scopu
Measurement of frictional forces in atomic force microscopy
No full textA new calibration method of frictional forces in atomic force microscopy (AFM) is suggested. An angle conversion factor is defined using the relationship between torsional angle and frictional signal. When the factor is measured, the slopes of the torsional angle and the frictional signal as a function of the normal force are used to eliminate the effect of the adhesive force. Moment balance equations on the flat surface and the top edge of a commercial step grating are used to obtain the angle conversion factor. After the factor is obtained from an AFM system, it can be applied to all cantilevers without additional experiments.11sciescopu
Facile stamp patterning method for superhydrophilic/superhydrophobic surfaces
No full textPatterning techniques are essential to many research fields such as chemistry, biology, medicine, and micro-electromechanical systems. In this letter, we report a simple, fast, and low-cost superhydrophobic patterning method using a superhydrophilic template. The technique is based on the contact stamping of the surface during hydrophobic dip coating. Surface characteristics were measured using scanning electron microscopy and energy-dispersive X-ray spectroscopic analysis. The results showed that the hydrophilic template, which was contacted with the stamp, was not affected by the hydrophobic solution. The resolution study was conducted using a stripe shaped stamp. The patterned line was linearly proportional to the width of the stamp line with a constant narrowing effect. A surface with regions of four different types of wetting was fabricated to demonstrate the patterning performance. (C) 2015 AIP Publishing LLC.1121sciescopu
A facile fabrication method for corrosion-resistant micro/nanostructures on stainless steel surfaces with tunable wettability
No full textSuperhydrophilic surfaces were fabricated on stainless steel surfaces via simple etching and oxidation processes and were modified by a self-assembled monolayer to provide superhydrophobic surfaces. The micro/nanostructure and reconstructed passivation layer of the stainless steel surfaces exhibited good mechanical durability and long-term stability. The corrosion resistance of the surfaces was investigated using sea water. The test results indicate that the reconstructed passivation layer of the surfaces provides excellent corrosion resistivity. The successful fabrication of large-area superhydrophilic/superhydrophobic surfaces offers the possibility of providing stainless steel surfaces with unique wetting characteristics for various industrial applications. (C) 2015 Elsevier Ltd. All rights reserved.1184sciescopu
Selective superhydrophilic/phobic coating using capillary pressure for positive-displacement nanoliter dispensing
No full textOwing to the fact that liquid-dispensing devices are used in a wide variety of scientific fields, including chemistry, biology, pharmacology, and mechanics, droplet dispensing has come to be regarded as a key technology with respect to micro/nanoengineering. Positive-placement dispensing technology is being used widely because it allows for a high degree of controllability without requiring a complex dispensing system; however, adhesion and slip-related issues limit the performance of this technology. In this letter, we report a technique for the fabrication of selective superhydrophilic/phobic coatings in syringe-type positive-displacement dispensing nozzle tips. The superhydrophilic capillary in the nozzle tip was coated selectively with superhydrophobic materials by exploiting the difference in the capillary pressure. The surface of the front part of the capillary was made superhydrophobic; it thus allowed the liquid to flow without adhesion. In contrast, the back part was made superhydrophilic; it retarded the flow of the liquid, holding it in place. Together, the two surfaces minimized the volume of the dispensed droplets. High-speed images of the dispensed liquid were taken to compare the two droplet-dispensation processes. It was found that the volume of the water droplets dispensed from the selectively coated nozzle tip was as low as 27 nL and much smaller than that of the droplets dispensed from the superhydrophobic nozzle tip. (C) 2015 Elsevier B.V. All rights reserved.110sciescopu
Wettability modified aluminum surface for a potential antifungal surface
No full textCirculation of contaminated air by air conditioning equipment promotes infection, notably bronchial diseases and the development of allergies. The evaporator of the air conditioning system has a key influence because its interior provides a favorable environment for growth of microbes. Most of the evaporator is manufactured from aluminum because of its mechanical properties, but it is poor at preventing contamination and growth of microorganisms. To overcome these problems, we use a non-wetting aluminum surface to retard microbial growth. This paper reports the extent of fungal growth on a superhydrophobic surface based on aluminum in comparison with superhydrophilic, weakly hydrophobic, and hydrophobic surfaces. Three common airborne fungi were used: Penicillium, Cladosporium, and Aspergillus. Separate experiments were performed direct and indirect contamination. In the direct contamination experiment, only the superhydrophobic surface was not contaminated. In the indirect contamination experiment, fungal contamination occurred on the superhydrophilic, weakly hydrophobic, and hydrophobic surfaces. There was a small amount of contamination on the superhydrophobic surface, but little spread. It is concluded that only the superhydrophobic surface is effective as an antifungal surface. (C) 2015 Elsevier B.V. All rights reserved.1166sciescopu
Exploiting the silicon content of aluminum alloys to create a superhydrophobic surface using the sol-gel process
No full textA superhydrophobic surface was fabricated on aluminum-silicon alloy (Al/Si alloy) by using a sol-gel process to first create an evenly distributed superhydrophilic silica gel layer from the silicon contained within the alloy itself. The elevated surface energy of this silica gel layer was then used to achieve a superhydrophobic surface through the subsequent application of a monomolecular silane coating. Evaluation of this surface confirmed an average water contact angle of 166.04 and a sliding angle of 8.86. The simplicity, low cost and low environmental impact of this fabrication method offers great potential for creating superhydrophobic Al/Si alloy surfaces on a commercial scale, thereby setting the foundations for a new field of industrial Al/Si alloy applications. (C) 2016 Elsevier B.V. All rights reserved.112218sciescopu
Facile method for preparing superoleophobic surfaces with hierarchical microcubic/nanowire structures
No full textTo facilitate the fabrication of superoleophobic surfaces having hierarchical microcubic/nanowire structures (HMNS), even for low surface tension liquids including octane (surface tension = 21.1 mN m(-1)), and to understand the influences of surface structures on the oleophobicity, we developed a convenient method to achieve superoleophobic surfaces on aluminum substrates using chemical acid etching, anodization and fluorination treatment. The liquid repellency of the structured surface was validated through observable experimental results;. the contact and sliding angle measurements. The etching condition required to ensure high surface roughness was established, and an optimal anodizing condition was determined, as a critical parameter. in building the superoleophobicity. The microcubic structures formed by acid etching are essential for achieving the formation of the hierarchical structure, and therefore, the nanowire structures formed by anodization lead to an enhancement of the superoleophobicity for low surface tension liquids. Under optimized morphology by microcubic/nanowire structures with fluorination treatment, the contact angle over 150 degrees and the sliding angle less than 10 degrees are achieved even for octane.11108sciescopu
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