Method and device for the marker-free detection of an analyte

A method for label-free detection of an analyte in a fluid, comprising:

• (a) providing at least one dielectric microsensor in a container, the at least one microsensor comprising a microresonator and an adsorbate layer applied to the microresonator for binding an analyte, wherein the microresonator consists of a particle, a dielectric material, and a fluorescent marker, the microresonator having a greater optical refractive index than the optical refractive index of a fluid to be analyzed, wherein the microresonator is suitable for allowing more than one resonance mode to be expressed in an interior of the microresonator when a fluorescence of the fluorescence marker is excited;
• (b) contacting the at least one microsensor with a fluid to be analyzed that could contain an analyte;
• (c) irradiating light onto the at least one microsensor in the fluid, the light having a wavelength suitable for exciting the fluorescent marker of the at least one microsensor to fluoresce;
• (d) detecting at least two optical resonance modes of the at least one microsensor from a detected fluorescent light of the at least one microsensor;
• (e) determining an optical thickness of the adsorbate layer of the at least one microsensor in the fluid from spectral positions of the at least two detected resonance modes via numerical algorithms;
• and
• (f) determining, based on the previously determined optical thickness of the adsorbate layer of the at least one microsensor, the extent to which an analyte in the fluid has bound to the at least one microsensor.

A device for the label-free detection of an analyte in a fluid, comprising:

• (a) a container containing at least one dielectric microsensor, at least one microsensor comprising a microresonator and an adsorbate layer applied to the microresonator for binding an analyte, wherein the microresonator consists of a particle containing a dielectric material and a fluorescent marker, the microresonator having a greater optical refractive index than the optical refractive index of a fluid to be analyzed, wherein the microresonator is suitable for allowing more than one resonance mode to be expressed in an interior of the microresonator when a fluorescence of the fluorescence marker is excited;
• (b) a light source for irradiating light onto the at least one microsensor, the light having a wavelength which is suitable for exciting the fluorescent marker of the at least one microsensor to fluoresce,
• (c) a spectral analysis unit configured to detect at least two optical resonance modes of the at least one microsensor from a detected fluorescent light;
• (d) an algorithmic unit configured to determine an optical thickness of the adsorbate layer of the at least one microsensor from spectral positions of the at least two detected resonance modes via numerical algorithms;
• and
• (e) an analysis unit which is configured to determine, based on the determined optical thickness of the adsorbate layer of the at least one microsensor, the extent to which an analyte has bound to the at least one microsensor.