1. Laboratory of Biochip Technology, School of Mechanical Engineering, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul 120-749, South Korea, and Emerging Center, SAIT, Samsung Electronics Co., Ltd., Mt. 14-1, Nongseo-dong, Giheung-gu, Yongin-si Gyunggi-do 446-712, South Korea