Toshitsugu Ueda

A novel lift off process and its application for capacitive tilt sensor

This paper presents a novel bi-layer (top image resist Shipley S1808 and bottom liftoff resist LOL2000) lift off process for patterning 3D devices. Resists are coated and patterned with an overhang profile on substrate before it is etched and before the film deposition. The key feature of the new lift off process is to create a resist undercut profile, which should be deep enough to reduce step coverage and durable to aggressive substrate etchant. Two-step development method was demonstrated effective. The resist profile is optimized by development time in the two step development process. Proposed lift off process was successively used for fabricating quartz based capacitive tilt sensor.

PBG Fiber Low Concentration Gas Sensor

The photonic bandgap fiber for a high-sensitivity, compact set-up, which enables the precise measurement of low concentration of gas was designed. Fiber was used instead the traditional glass gas cell during the spectroscopic measurements. Ar ion beam was proposed among the other methods to process the inlet and outlet surface of fiber and adjust it to the required parameters. The gas flow inside PBF fiber and its optical properties were investigated.

Sensing of Gas Concentration Using Photonic Bandgap Fiber

Photonic bandgap (PBG) fiber was developed for a new gas-sensing device. The micro-capillary gas flow inside fiber and light guiding parameters were estimated in order to develop a high-sensitivity gas concentration measuring system. Darcy-Weisbach equation for non-compressible flow and quasi-Panhandle equation for compressible gas flow were used for the calculation of gas velocity. Core diameters of fibers ranged from 10.9 to 700 mum. The results of numerical simulations were compared with experimental results. Attenuation was calculated and concentrations of ammonia and CO2 were measured.

Application of Photonic Bandgap Fiber in Gas Concentration Measurement

An idea of high-sensitivity gas concentration measuring system basing on photonic bandgap fiber (PBG fiber) was studied. Several types of PBG fibres of various parameters were designed. Core diameters ranged from 10.9 to 26 mum. Capillary gas flow rate within the fiber was simulated and measured. Attenuation of newly produced fibres was investigated and concentration of ammonia gas was measured using the new type sensing system

Evaluation of Laser-Induced Breakdown Spectroscopy Quantitative Sensing Performance Using a Micro-Droplet Ejection System

A new and reliable evaluating method for a laser induced breakdown spectroscopy (LIBS) quantitative measurement using a micro-droplet sample ejection system is introduced. LIBS has been investigated extensively to establish proper chemical analysis of specimens. There is an indefinable boundary which is ablated or not when laser focusing on the sample. Generating micro-droplets from concentration tuned solution, and leading to the correct beam spot area are important for determining the total amount of media in a droplet. The LIBS measures the sodium chloride concentration of a micro-droplet as a quantitative measurement by recording intensity from the sample plasma. As a result, LIBS with the micro-drop ejection system produced greater intensities than the old technique of bulk-liquid measurement based on data from 100 laser pulse shots.

Study of laser-induced breakdown spectroscopy from micro-droplet of NaCl Solution

The laser-induced breakdown spectroscopy (LIBS) using micro-droplet sodium chloride solution is presented. Micronizing the sample made possible that whole volume of a sample was confined in the laser beam spot area and was separated from its surrounding condition. If the samples physical state was liquid, the density of solution could be controlled as needed. Originally designed ink-jet system for sampling procedure was presented. According to the new method, improved calibration curves for the LIBS quantitative measurement were obtained.

Simulation of particle size measurement with LIBS

The problem of small solid particle size and material detection is important for industrial and environmental applications. Previous investigations have shown the possibility of using the laser breakdown method to address the first issue; the sensitivity of this method is a thousand times higher than that of conventional methods. However, for small particle sizes, the damage threshold of the solid target in this case is very close to the breakdown point of pure gas. After breakdown, there is a small volume of dense hot plasma that emits radiation. We analyzed this radiation especially at the late stage using an analytical model and simulation code, and found that the emission intensity varied depending on the laser type and plasma parameters including initial particle size