Patent ID: 8277750

Claim:
A detector for use in a chemical sensor apparatus, the detector detecting a measurement-target substance in a medium by detecting adsorption of the measurement-target substance on a detection surface of the detector, the detector comprising: (i) an adsorption layer on the detection surface for detecting the substance, the adsorption layer including an element-substituted apatite, (ii) a crystal plate or a substrate, (iii) a metal electrode, the chemical sensor apparatus employing a quartz crystal microbalance method or a surface plasmon resonance method, wherein the element-substituted apatite is a hydroxyapatite including both Ca and a phosphate group, part of whose elements is substituted with Na, wherein the adsorption layer and the metal electrode are provided on opposing sides of the crystal plate or the substrate, such that the adsorption layer and the metal electrode face each other with the crystal plate or the substrate disposed between the adsorption layer and the metal electrode.