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A droplet manipulation is one application of a surface acoustic wave (SAW) device. In this paper, a novel digital microfluidic system using SAW device is described. The system which is called micro-laboratory consists of sensor plate/matching layer/ piezoelectric substrate. The piezoelectric substrate is used for generating the SAW. At the piezoelectric substrate and matching layer interface, the SAW radiates a longitudinal wave into the layer. When the longitudinal wave reflects at the sensor plate and matching layer interface, a bulk acoustic wave (BAW) is generated into the plate. The BAW is used to manipulate a droplet on the sensor plate. For detecting droplet characteristics, an interdigital electrode (IDE) is fabricated on the sensor plate. Using the IDE, impedance change due to a urease catalytic reaction is measured. The results indicate that the proposed system is able to use a detector of urea concentration.