Woo-Suk Chong

Basic Study to Develop Biosensors Using Surface Acoustic Waves

In this paper, we present a study of the bonding between piezoelectric substrates and semiconductor materials. We have studied [O. S. Wolfbesis: Fiber Optic Chemical Sensors and Biosensors, 1st ed. (CRC Press, Boca Raton, 1991) p. 21.] the surface state (hydrophilic) of GaAs, LiNbO3 and quartz substrates after different treatments methods [R. Hughes, A. Ricco, M. Butler and S. Martin: Science 254 (1991) 74.], the effects of migration of water molecules out of bonding surfaces induced by microwave and laser radiation. When Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) is used as a piezoelectric material, we have evaluated if PMN-PT can be made practically available for a new surface acoustic wave (SAW) biosensor detecting protein. The experimental results clarified that improvements in the bonding process are effective in obtaining a stronger bonding interface between the piezoelectric substrate and semiconductor materials. The frequency filtering of the central frequency of the PMN-PT substrate is also superior to that of the LiTaO3 substrate, but the result was not completely satisfactory. However, the electromechanical coupling coefficient of the PMN-PT substrate is excellent, therefore it will be used as a SAW sensor, in the near future, provided that new interdigital transducer (IDT) design will also be available to increase the frequency of filtering.

Development of biosensor using surface acoustic wave

In this research, in using a piezoelectric material of Pb(Mg/sub 1/3/Nb/sub 2/3/)O/sub 3/-PbTiO/sub 3/ (PMN-PT), which has a high electromechanical coupling coefficient, we have tried to see if the material can be practically available as a new surface acoustic wave (SAW) biosensor to detect protein. As the results, the frequency filtering of the central frequency of the PMN-PT substrate is a superior result to that of the LiTaO/sub 3/ (LT) substrate, but the result was not completely satisfactory. We know there is a problem in the design of inter-digital transducer (IDT) pattern. The waves transferred through the input terminal forms SAW which is sure to be transferred to the direction of the output terminal and the backward direction of the input terminal. This reflected wave is reiterated with SAW, which is transferred to the output direction, and so the frequency filtering gives a not good result. The electromechanical coupling coefficient of the PMN-PT substrate is excellent, and as such we can use it as a SAW sensor, in the near future, provided that there is a new IDT design to increase the frequency filtering.

A quantitative evaluation of golf swing

The purpose of this study was quantitatively evaluate golf swing. This was performed by comparing the physiological and kinematical factors of the experts and beginners. A system for measuring impact was built to acquire a club head trace. The results obtained showed that the club head speed of experts appeared to have values about 8.6% over that of beginners, and the speed with club3 showed was about 7.9% higher than that of a club7. In the case of beginners, an increase of club length did not cause an increase in club head speed. In terms of address time, experts were shorter by about 20.6% than beginners, but there were no significant differences among types of irons used for both experts and beginners. Dominant /spl alpha/ waves when static case mean that a golfer maintains a stable mental state, /spl beta/ and /spl beta/II waves were larger in the right hemisphere than in left, and /spl alpha/ wave are lower in the right hemisphere. During the swing, /spl beta/ and /spl beta/II waves are dominated high strong concentration, /spl alpha/ waves were dominant and /spl beta/. /spl beta/ll waves attenuated in the right hemisphere.

Design of the Implantable Artificial Lung using Computational Fluid Dynamics

An artificial implantable lung would be a useful device to support ARDS patients awaiting lung transplantation. In this study, the characteristic of fluid flow in the new type lung assist devices has been established using CFD. According to the modeling, it is believed that the tangential type module would be more beneficial to the fluid flow, and 2 ports would influence better than 1 port. However, such results are simple modeling by CFD, and therefore need to be confirmed by actual experiments.

Development of viscosity sensor using surface acoustic wave

The purpose of this study is to materialize the viscosity sensor by using the SH-SAW sensor of which the center frequency is operated at higher than 50 MHz. In order to measure the viscosity, SAW sensor of which the center frequency is operated at 100 MHz is developed. By using the developed sensor, phase shift, delay time, insertion loss, and frequency variation are measured at different viscosity. The result shows that the phase shift difference between the viscosity variations is such that the difference between the distilled water and the 100 % glycerol solution is approximately , the change of the insertion loss is approximately 9 dB, and the difference of frequency variation is approximately 5.9 MHz. Therefore, it is shown that viscosity of unknown solution can be measured with the surface acoustic wave sensor.

Study on the Bonding Process between Thin film and Piezoelectric Materials

The purpose of this study is to obtain strong bond strength at the interface between piezoelectric substrates and semiconductor thin films to be applied for the manufacture of high-performance acoustic wave semiconductor coupled device. For this purpose, we have compared and examined the effects of different surface treatment methods on hydrophile properties at the surface of the piezoelectric substrates. Moreover, we have observed the effect of microwave and laser on the elimination of water molecules at the interface. As for the piezoelectric substrates, dry method for surface treatment was found to be superior in the control of hydrophilicity of the surface compared to wet method. On the other hand, both microwave and laser were found to be effective in the elimination of water molecules in the interface.