Abstract: A new type of piezoelectric crystal sensor detector is designed. The reference wafer and the sensitive wafer are in touch with the detected gases directly at the same time. The mercury vapor response and the interference influence of moisture are tested using the piezoelectric crystal mercury sensor with a double wafer.Results show that in a wide range mercury vapor detection is not influenced by the sensor,when the reference wafer touches the detected gases. Moreover the interference of moisture or any other gas can be greatly decreased.

Key words: piezoelectric crystal, sensitive water, reference wafer, mercury sensor