Provided herein is a surface acoustic wave (“SAW”) sensor device including an isolation component of a target biomolecule. A sample containing the target biomolecule is separated by its size using electrophoresis, and sequentially reacts with a SAW sensor. In other words, the device is capable of detecting the target biomolecule by separating biomolecules using electrophoresis, and applying the separated biomolecules to the SAW sensor.