Patent ID: 7700348

Claim:
A biochip comprising a substrate containing a reflecting main surface, wherein the main surface presents localized sites covered by a transparent layer to enhance fluorescence, whereby the sites are made sensitive to fluorescence detection of fluorescent light emitted by target molecules marked by a fluorescent material that is deposited over the transparent layer, wherein the transparent layer has an optical thickness of (2k+1)λ/4 where k is a positive integer or zero and where λ designates a wavelength lying in the range from a wavelength λ 0 at which fluorescence of the fluorescent material is excited to a wavelength λ 1 at which the fluorescence of the fluorescent material is emitted, and further wherein, outside the sensitive sites, the main surface of the substrate is covered in a transparent layer of thickness different than that of the transparent layer of the sensitive sites, the thickness outside the sensitive sites being of mλ′/2 where m is a positive integer and λ′ designates a wavelength lying in the range λ 0 to λ 1 .