This paper presented the method to detect the degradation level of insulation oil for transformer. Degradation of insulation oil for transformer is due to both mechanical and chemical deterioration. Metallic particle and organic material such as a dust are known as the main reason of mechanical deterioration. According to degradation and oxidation of insulation oil for the time of transformer operation, total acid number (TAN) will be increased, sludge will be appeared, and finally conductivity will be decreased. Designed sensor, which is an inter-digit capacitive type, was fabricated by using MEMS technology. Size of sensor is 9 mm (length) x 7 mm (width) x 1 mm (thickness). From the tested result, when the oil is aged, the capacitance increases and the impedance decreases. And the result shows the good proportionality with time.
The fabricated system is advantageous due to its low cost and simple structure. This is possible because it replaces many optical lenses and expensive equipment with optical fibers. We tested various optical fibers to select a suitable fiber for effective micro flow cell cytometry. In order to align between micro nozzle and optical fibers, a guide channel was fabricated by Si wafer etching with MEMS (Micro Electro-Mechanical System) technology. The micro flow cell cytometry using optical science and MEMS technology. The optical science using multi mode optical fiber and He-Ne laser (20mW, 658nm). The guide channel was fabricated by MEMS technology. The output voltage was as high as about 300 mV, so we are going to use a light source which has relatively small output power. By injecting various cells, we were able to detect cells. In addition, we can use the micro flow cell cytometry for analyzing cells (1, 2). We have no doubt that this micro flow cell cytometry can contribute to the development of biological engineering and clinical testing and it can be practically used in diagnoses of particular diseases and biological symptoms and invitro diagnostics (7, 8).
This research is about a thermal flow sensor, suggesting a new structure to improve the detection of airflow directions in any flow direction as well as to realize its interface circuit with simple OP amp circuits. A flow direction sensor was fabricated using MEMS technology. Pt was used as resistive material because of its very stable physical properties. The structure of the sensor, consisting of one heater at the center and four detectors surrounding the heater,
is a symmetrical circular-type to generate uniform output regardless of various flow directions. The designed sensor operates based on the relative output difference of the four detectors in response to temperature variations induced by airflow. Therefore, flow directions can be easily detected by amplifying and calculating each output signal of the four detectors. As a result, the interface circuit could be realized with simple circuits. It was designed with popular
instrumentation amplifiers and OP amps and integrated into ASIC chips using CMOS technology. The fabricated sensors were tested at 5 m/s and 10 m/s. The response time was some ten seconds and the maximum angle difference compared to flow angle was 5°. The results demonstrate that the suggested structure of sensors could be applied to the detection of flow directions and the test results could be obtained with a simple interface circuit.
The proper exchange of automobile engine oil leads to the saving of resources as well as the safe maintenance of automobile engine. In this paper, we designed the capacitive sensor to monitor changes in the dielectric constant of the engine oil and we fabricated the sensor by using semiconductor fabrication technology. Experiments have been carried out with the fabricated sensor equipped on oil chamber using a typical fully-formulated oil. The capacitance of sensor increased at about 3 percent per 1,000km.