Patent ID: 7733491

Claim:
A sensor device for detecting a target substance based on a change in optical properties of a vicinity of a sensor medium comprising: the sensor medium comprising a substrate, and a metal film having a plurality of slit openings formed on the substrate; a light source unit that irradiates polarized light having a wavelength toward the sensor medium; and a light detecting unit that detects light by way of the sensor medium, wherein the plurality of slit openings are arranged periodically in a first direction in the metal film, a length of each of the plurality of slit openings in the first direction and an interval between the slit openings in the first direction are equal to or less than the wavelength of the light, wherein each of the plurality of slit openings extends in a second direction orthogonal to the first direction and has a length in the second direction that is greater than the length in the first direction, and wherein a localized plasmon resonance generated in the sensor medium by the polarized light having an electric field parallel to the first direction causes a change of a spectrum or an intensity of light detected by the light detecting unit, and the change in optical properties caused by a presence of the target substance in the vicinity of the sensor medium is detected based on the change of the spectrum or the intensity of light.