ABSTRACT
Structural colors based on nanostructured surfaces are an environmentally friendly alternative to dyes and pigments. In this study, structural colors were produced by spherical silica nanoparticles. By controlling the size of the spherical silica nanoparticles, the changes in color were controlled. The sizes of the nanoparticles were controlled by adjusting the ammonia content in the conventional Stöber method. Spherical silica nanoparticle powders were obtained using a centrifuge and an ultrasonic grinder oven, which were subsequently dispersed in deionized water and alcohol for dip coating. The particle sizes of the samples increased with increase in the amount of ammonia used in the synthesis process and were not affected by the dip coating. Spherical silica nanoparticles were uniformly arranged on the surface of the glass slides for all the samples studied. Thus, the structural colors produced by the spherical silica nanoparticles changed according to the particle size, which can be controlled by the ammonia content during synthesis.
Subject(s)
Nanoparticles , Silicon Dioxide , Biomimetics , Particle Size , WaterABSTRACT
In this paper, surface characteristics of 3D printed structures fractured at low temperature environments are analyzed. The samples are fabricated by using ABS (acrylonitrile butadiene styrene copolymer) material, and the structures are constructed by the well-known honeycomb models using a FDM-Type 3D printer. To analyze the fracture surface of the samples constructed uniquely by using the 3D printer, the bending loads are applied to the samples at 30, -10 and -50 °C, respectively. The characteristics of the fracture surfaces of the 3D samples are also observed by the FE-SEM (field emission scanning electron microscope) equipment. From this experiment, it is evaluated that the fractured surface of the 3D sample is very rough at 30 °C, while it is smooth at a relatively low temperature. Also, several unique features of the fracture surface of a 3D printed sample structured by honeycomb models are also examined.
ABSTRACT
There are limitations on the shape of models that can be measured with commonly used temperature sensors. These disadvantages are difficult to measure temperatures of the curved surface. To overcome the shortcomings, a smart paint for temperature measurement is proposed in this work. A polymer solution was prepared for viscosity of the paint and dispersion of materials. The BaTiO3 and Ag nanopaste are used for PTC characteristics and conductivity of the paint, respectively. Smart paint were analyzed the arrangement and shape of particles according to the processes and production methods. Also, the change of resistance was measured while increasing the temperature. The results show that resistance increased as the temperature increased. The performance of the manufactured smart paint was confirmed as a surface temperature sensor.
ABSTRACT
In this paper, a mechanism of sensors for micro crack detection is proposed according to circuit disconnection. In order to detect micro cracks, sensitive sensors based on micropatterning using a electrohydrodynamic (EHD) technology are necessary. For EHD printing, it is essential to find an optimum condition between ink materials and environmental parameters. Therefore, the distribution of the jetting mode between the flow rate and the voltage is confirmed through experiments. Metal-grid was patterned and resistance of each circuit by crack occurrence was measured. The resistance changes are occurred at the position where the crack is generated, and the crack position can be estimated with grid type sensors. The resistance in the cracked circuits are relatively larger than it in non-cracked circuits. It was confirmed that micro cracks were well detected by using the proposed crack sensors and mechanisms.
ABSTRACT
Novel gradient focal point (GFP) methods by use of the gradient curvature cylindrical lens, the gradient thickness cylindrical lens and a tilted imaging sensor are proposed for the optical profiler. With the employed simple idea that the different divergence angle of an input beam to the lens generates the different focal position, the height information of one point can be obtained just in a single-shot by GFP approaches. The feasibility of the proposed system is demonstrated to be an alternative to optical profilers.
