Target substance capturing device

A target substance capturing device that captures a target substance with a biosensor using a photonic crystal including a reflection surface that reflects irradiated light, and having a plurality of non-flat portions arrayed on the reflection surface, wherein

• each of the non-flat portions belongs to one of a plurality of unit arrays in which the non-flat portions are arranged such that a center of each of the non-flat portions superposes a position of a vertex of a regular triangle, each unit array of the unit arrays being a respective unit triangle of a plurality of unit triangles, the plurality of unit triangles forming a lattice pattern, the unit arrays are arranged in such a manner that:
• the non-flat portions belonging to the one of the unit arrays are different from the non-flat portions belonging to the unit arrays adjacent to the one of the unit arrays;
• each unit triangle has a g-center that is a center of gravity that superposes an intersection of the lattice pattern, the lattices intersecting with each other at an angle of 60°;
• the lattice pattern has a lattice cycle of a distance that is a distance between the g-centers adjacent each other;
• the non-flat portions are not arranged in flat-center positions, each of which is a center of gravity of a triangle that is made by connecting the g-centers of adjacent three of the unit triangles having sides that are parallel to straight lines included in the lattice pattern;
• each of the flat-center positions are adjacent to and surrounded by three pairs of the non-flat portions, each pair of the three pairs of non-flat portions belonging to a respective one of the unit arrays;
• and
• the non-flat portions are arranged in at least two pairs of adjacent rows on the reflection surface, each pair of the adjacent rows comprising a first row and a second row, wherein the second row has two times as many of the non-flat portions as the first row.