Papers by Author: Yang Ju

Abstract: Using the microwave atomic force microscope (M-AFM) measuring system, the sample of Au nanowires arranged on glass wafer was sensed with three kinds of scanning speed. As the results shown, the spatial resolution of topographies is increased with the decrease of scanning speed. However, the precision of microwave images is not changed much with decreasing the scanning speed. Since M-AFM with the compact microwave instrument can always implement the real time measurement, the variation of scanning speed will not affect the microwave measurement.

Abstract: A technique to detect delamination in composite materials by noncontact, rapid and high sensitive microwave reflectometry with a focusing mirror sensor was proposed. The focusing mirror sensor, which has high sensitivity and resolution, is expected to detect delamination sensitively. In this paper, the ability of microwave inspection to detect delamination in glass fiber reinforced plastic (GFRP) and carbon fiber reinforced plastic (CFRP) was verified. As the results, the existences of 100 μm thick delamination in 3 mm thick GFRP laminate and 2 mm thick CFRP laminate were detected.

Abstract: Many studies have focused on the fabrication of Cu nanowires, because of their potential applications in diverse fields such as nanoelectronics and gene delivery. In this study, we successfully fabricated Cu nanowires by electrochemical deposition method. Cu nanowires was synthesized by electroplating from a 0.4M CuSO₄ bath, and the current was 0.005A. The length of nanowires can be controlled via deposition time and current. After depositing for 60 minutes, the length of the nanowires is approximately 10 µm. Serum coated and non-coated nanowires with the concentration of 10², 10³, 10⁴ and 10⁵ were added to 96-well cell culture plate in which mesenchymal stem cells were pre-seeded. After incubating for 3 days, cytotoxicity of nanowires was measured with MTT assay method. Results indicated that cytotoxicity increased as the increase of nanowires concentration. Serum coated nanowires had higher cell viability as compared with the non-coated group.

Abstract: To confirm the sensitivity in the measurement of electrical properties affected by the nano structure of microwave AFM (M-AFM) probe, three kinds of M-AFM probe with a nano-slit on its tip in different width (75 nm, 120 nm and 160 nm) were investigated. Au and glass samples were measured by the probes working at a non-contact AFM mode. The M-AFM probe with the nano-slit having the width of 75 nm, by which the difference of the measured voltage between Au and glass samples is 55.1 mV, shows the highest sensitivity for detecting electrical properties of materials. As the result illustrated, the M-AFM probe with smaller width nano-slit on the tip can be considered to be an ideal nano structure.

Abstract: Migration of atoms is presented to be utilized for fabrication of metallic micro/nanomaterials by controlling the phenomenon. Two kinds of migration phenomena are treated; one is electromigration and the other is stress migration. In addition to the formation of micro/nanomaterials, some achievements in enhancing their functions are demonstrated. One is a technique to fabricate nanocoils from the formed Cu nanowires. The others are techniques to weld or cut the micro/nanowires by using Joule heating. Finally, regarding evaluation of mechanical and electrical properties of the micro/nanomaterials, the concentrated-mass cantilever technique in atomic force acoustic microscopy and the four-point atomic force microscope technique are shown to be powerful tools, respectively.