A sensor is disclosed. The sensor comprises a first substrate; a second substrate positioned relative to the first substrate; a first electrode located between the first substrate and the second substrate, the first electrode formed on the second substrate; a sensing portion covering at least a part of the first electrode and further covering at least a portion of the second substrate; a pad electrode located between the first substrate and the second substrate, wherein the pad electrode is formed on the second substrate and is electrically coupled to the first electrode; and a bonding pad located between the first substrate and the second substrate, wherein the bonding pad is formed on the first substrate and is electrically coupled to the pad electrode.