A multi-stage sensor is situated on the head transducer and configured to interact with a magnetic recording medium. The device enriches ions utilizing the following characteristic: compound ions with specific ion mobility maintain a dynamic balance for a period of time in a flow field under the combination of a carrier gas and a suitable electrical field against the direction of the carrier gas. , 2) allowing the melted polylactic acid to cool down to solidify at an ordinary or a lower temperature, 3) pulverizing the solidified polylactic acid at an ordinary temperature into powder, and 4) compressing the powder or a mixture powder prepared by addition of another ingredient, e. The connecting line is connected to the first contact hole at one end, as described above, extends directly above a capacitor line in the Y direction, and is connected to the capacitor line via a second contact hole at this position.