Patent ID: 8377380
Filing Date: 2013-02-19
Classification: G01N,Y10T

Abstract:
1. A sensing device for sensing a substance to be sensed in a sample fluid based on an oscillation frequency of an oscillation area for measurement and an oscillation area for reference, which are formed on a piezoelectric piece, comprising: the piezoelectric piece; a pair of first excitation electrodes provided on two sides of the piezoelectric piece, so as to form the oscillation area for measurement on the piezoelectric piece; a pair of second excitation electrodes provided on the two sides of the piezoelectric piece so as to form the oscillation area for reference, separated from the oscillation area for measurement, on the piezoelectric piece on which the oscillation area for measurement has been formed; an absorption layer, which absorbs the substance to be sensed in the sample fluid, and which is formed on one excitation electrode, from among the pair of first excitation electrodes that form the oscillation area for measurement, which is located on one of the two sides of the piezoelectric piece; a surrounding member provided, to form a sample fluid supply space common to the oscillation area for measurement and the oscillation area for reference, on one surface side of the piezoelectric piece, to be positioned outside of the first excitation electrodes and the second excitation electrodes, and to surround a first electrode of the pair of first excitation electrodes and a second electrode of the pair of second excitation electrodes in a circular manner; and a holding member holding an outside of the oscillation area for measurement and the oscillation area for reference on the other surface side of the piezoelectric piece; a first lead out electrode, formed on the piezoelectric piece, for connecting the first electrode of the pair of first excitation electrodes to a conductive path provided on the holding member; and a second lead out electrode, formed on the piezoelectric piece, for connecting the second electrode to a conductive path provided on the holding member; wherein the first electrode of the pair of second excitation electrodes and the second electrode are formed on one surface side of the piezoelectric piece, in the following shapes: a. the first electrode and second electrode are formed symmetrically to be separated from each other into left and right with respect to a center of a circle and being a planar shape contoured to the sample fluid supply space to form strip-shaped left side area and right side area extending in a longitudinal direction in a parallel manner, b. each of two corner portions on a left side of the left side area and two corner portions on a right side of the right side area are set to have a size to protrude outside of the circle, and c. the corner portions protruding to the outside are cut to make the left side area and the right side area be positioned inside of the circle, and the first electrode and the second electrode are respectively formed on the left side area and the right side area.