Resumen
[0001] The present invention is an interferometric detection method which allows improving the limit of detection and taking interferometric measurements with a much higher degree of sensitivity than that allowed by interferometric devices known in the state of the art. The invention is characterized by the use of two interferometric measurements, a first reference measurement in a wavelength range and a second measurement on the observation region in at least the same wavelength range in which it is to be determined whether or not there are changes, where a quotient function, which is the function to be analyzed for establishing parameters determining the change experienced in the observation region with a high degree of sensitivity, is constructed from said measurements.
Reivindicaciones
1. An interferometric detection method comprising the following steps: a) taking a first interferometric measurement by means of an interferometer in turn comprising an observation region, where said interferometer is suitable for receiving an input light beam and provides an output beam resulting from interrogating the observation region, where said first interferometric measurement is taken by exciting the interferometer with a light beam which is at least in a wavelength range [λ<1> ,λ<2> ], b) characterizing the observation region of the interferometer by means of a function I ref Interferometric λ 1 λ 2 , <img class="EMIRef" id="467962570-ib0078" /> which represents the measured intensity modulated by the reference interferometer, or in other words, which represents the output of the interferometer as a function of the exciting light beam wavelength, c) conducting an experiment susceptible to modifying the observation region or on the observation region of the interferometer used in the first measurement or on a second observation region interferometrically equivalent to the first observation region, d) taking a second interferometric measurement by characterizing the modified observation region of the interferometer during the experiment by means of a function I out Interferometric λ 1 λ 2 , <img class="EMIRef" id="467962570-ib0079" /> which represents the measured intensity modulated by the interferometer at the output of the interferometer as a function of the exciting light beam wavelength, where in this second interferometric measurement the exciting light beam shows the same spectrum as the exciting light used in the first measurement in at least the wavelength range [λ<1> ,λ<2> ], e) constructing a transduction functionftrans resulting from the quotient f trans λ 1 λ 2 = I out Interferometric λ 1 λ 2 I ref Interferometric λ 1 λ 2 <img class="EMIRef" id="467962570-ib0080" /> f) establishing a measurement parameter on functionftrans to determine the degree of modification of the observation region, preferably among the following: ○ the amplitude of one of the peaks of functionftrans , preferably corresponding to the smaller wavelength, ○ the amplitude between two consecutive peaks of functionftrans , ○ the change in slope in functionftrans by a pre-established wavelength value; or, ○ the variation of the area under the curveftrans [λa , λb ], where the range [λa , λb ] is a sub-range of [λ<1> ,λ<2> ], g) providing the value of the measurement parameter measured on functionftrans obtained in step f). 2. The method according to claim 1, characterized in that : • there is provided one or more second interferometers in turn comprising an observation region suitable for receiving an input light beam and providing an output beam resulting from interrogating the observation region carrying out an interference process, where this second interferometer and its observation region is equivalent to the first, i.e., given the same light beam conditions for exciting the interferometer and the same observation region conditions provides the same wavelength-dependent intensity as the first interferometer, • the characterization of the observation region of the interferometer by means of a function I ref Interferometric λ 1 λ 2 <img class="EMIRef" id="467962570-ib0081" /> according to step c) is carried out in the first interferometer, • the experiment on the observation region of the interferometer susceptible to modifying the surface of the observation region according to step d) is conducted in each of the second interferometers, the observation region being characterized in these same second interferometers according to step d) after the experiment by means of function I out Interferometric λ 1 λ 2 , <img class="EMIRef" id="467962570-ib0082" /> which represents the intensity measured at the output of each of the second interferometers depending on the wavelength of the exciting light beam, • steps f) and g) are carried out for each second interferometer. 3. The method according to claim 1 or 2, characterized in that the measurement parameter measured on functionftrans [λ<1> ,λ<2> ] uses an auxiliary functionF (x) such that said parameter takes measurements on composition of functions F ° f trans λ = F f trans λ <img class="EMIRef" id="467962570-ib0083" /> 4. The method according to claim 3, characterized in that composition of functionsF (ftrans (λ)) is F f trans λ = I out Interferometric λ f trans λ - 1 2 f trans λ + 1 <img class="EMIRef" id="467962570-ib0084" /> which can also be expressed as F f trans λ = 1 + I out Interferometric λ - I ref Interferometric λ 2 I ref Interferometric λ <img class="EMIRef" id="467962570-ib0085" /> 5. The method according to claim 1 or 2, characterized in that the interferometer or the interferometers are resonators. 6. The method according to any of the preceding claims, wherein the interferometer comprises: • a lens with a large aperture suitable so that the incident light beam interrogating the observation region does it simultaneously at a specific inclination range, • an image sensor suitable for capturing in different points of the sensor the light coming from the beam, after passing through the observation region, depending on the incident angle in the observation region; where • there is provided a functionI (θ) by measuring the intensity in the sensor corresponding to each value of the inclination of incidence in the observation region, • there is established a bijection λ=λ(θ) linking λ and θ, • functions I ref Interferometric θ <img class="EMIRef" id="467962570-ib0086" /> and I out Interferometric θ <img class="EMIRef" id="467962570-ib0087" /> are expressed as I ref Interferometric λ <img class="EMIRef" id="467962570-ib0088" /> and I out Interferometric λ <img class="EMIRef" id="467962570-ib0089" /> for being used in step f). 7. The method according to any of claims 1 to 6, characterized in that the modification of the observation region (R) of the interferometer is a functionalization step for functionalizing the surface of said observation region (R) by incorporating molecular receptors (3), and where the measurement leading to characterization I ref Interferometric λ <img class="EMIRef" id="467962570-ib0090" /> is carried out before functionalization step and the measurement leading to characterization I out Interferometric λ <img class="EMIRef" id="467962570-ib0091" /> is carried out thereafter. 8. The method according to any of claims 1 to 6, characterized in that the modification of the observation region of the interferometer comprises a step of incorporating a sample susceptible to incorporating target molecules (4) on a surface functionalized with molecular receptors (3) susceptible to recognizing said target molecule (4), and, where the measurement leading to characterization I ref Interferometric λ <img class="EMIRef" id="467962570-ib0092" /> is carried out before incorporating the sample in the observation region (R), and the measurement leading to characterization I out Interferometric λ <img class="EMIRef" id="467962570-ib0093" /> is carried out after incorporating a sample susceptible to incorporating molecules (4) corresponding to the molecular receptors (3). 9. A device comprises: • an interferometer comprising at least one observation region (R), • a light emitter suitable for emitting a light beam striking the observation region (R), • reading means for reading the output light beam of the interferometer suitable for providing the interferometric signalI (λ), • storage means for storing the interferometric signal in a wavelength range, • a central processing unit suitable for carrying out a method according to any of the preceding claims. 10. The device according to claim 9, characterized in that it has one or more second interferometers wherein each of them comprises at least one second observation region (R) equivalent to the first. 11. The device according to claims 9 or 10, characterized in that the reading means have filters for limiting the wavelength range of the light received. 12. The device according to any of claims 10 to 11, characterized in that it has a movable support suitable for placing either the first interferometer or the second interferometer under the light beam from the light emitter. 13. The device according to any of the preceding claims, characterized in that it additionally comprises: • a lens with a high numerical aperture the focus of which is located on the observation region (R), • the light beam is suitable for striking in a range of lens diameters which are in turn deviated towards the observation region according to different incident angles; and where the output light beams pass through the lens to reach the reading means, • the reading means for reading the output light beam of the interferometer is suitable for receiving the output light corresponding to different incident angles on the observation region (R) in a differentiated manner.
