Method and device for analysing a sample, implementing a resonant support

A method for detecting an analyte within a sample, the sample lying on a resonant holder, the resonant holder comprising a surface on which lie a plurality of photonic crystals, which are separate from one another, such that the sample lies between a light source and the photonic crystals, the photonic crystals being such that:

• at least two of the photonic crystals are configured to make contact with the same analyte,
• one resonant wavelength is associated with each photonic crystal, the resonant wavelength varying as a function of an amount of analyte in contact with each photonic crystal, the resonant wavelengths of the photonic crystals defining a resonance spectral band lying between 200 nm and 1500 nm;
• and
• transmission or reflection of light by each photonic crystal is maximum at the associated resonant wavelength;
• the method comprising:
• a) illuminating the resonant holder with the light source in an illumination spectral band that at least partially covers the resonance spectral band, such that a plurality of photonic crystals addressing the analyte are simultaneously illuminated and an illumination intensity is variable, in the resonance spectral band, according to a spectral illumination function;
• b) acquiring, with an image sensor, a measurement image of the resonant holder, the measurement image comprising different regions of interest, each region of interest being optically coupled to one photonic crystal such that each region of interest represents an intensity transmitted or reflected by each photonic crystal while the resonant holder is illuminated;
• c) using a reference image, the reference image being representative of an image acquired by the image sensor, when the resonant holder is illuminated in the illumination spectral band in a reference configuration, in the absence of analyte;
• d) comparing the measurement image, acquired in b), with the reference image;
• and
• e) based on the comparison, determining whether the analyte is present in the sample,
• wherein
• each photonic crystal comprises:
• first holes formed in a thin layer and having a first dimension, the first dimension being a radius or a diagonal, the first holes defining a first periodic pattern;
• and
• second holes formed in the thin layer and having a second dimension, the second dimension being strictly smaller than the first dimension, the second holes defining a second periodic pattern;
• the second pattern and the first pattern are offset with respect to each other, parallel to the surface of the resonant holder by a spatial offset, the spatial offset being variable between at least two different photonic crystals;
• and
• the resonant wavelength associated with each photonic crystal depends on the first dimension, on the second dimension, and on the spatial offset.