A mixer apparatus for use with a vessel centered about a longitudinal axis is disclosed. First and second internal data signals complementary to each other are supplied to a level shifter, thereby third and fourth internal data signals complementary to each other are generated by changing amplitude values of the first and second internal data signals. The one dimensional sensor layer includes plural sensing cells which correspond to the key areas, and respective cells are electrically connected to a capacitance sensing circuit. Each semiconductor chip has bonding pads.