Patent ID: 9632031
Date: 2017-04-25
CPC Classifications: G01N

Claim:
1. A system for the in vitro detection and/or quantification by fluorometry of at least one analyte in a sample of fluid, the system comprising: a radiation source emitting a main beam in a given wavelength called emission wavelength; an optical splitter arranged at the output of the radiation source for splitting the main beam into a first sample-energizing beam and a second reference beam; a first photodetector designed for providing a first analog detection signal in response to detecting a fluorescence ray emitted by the sample, in a so-called fluorescence wavelength as a result of the excitation induced by the first energizing beam; a second photodectector designed for providing at the output a second analog detection signal in response to a detection of the second reference beam; a generator outputting a sinusoidal carrier signal at a predefined frequency called carrier frequency, and at least one digital demodulation signal at this same carrier frequency, wherein the sinusoidal carrier signal is in the form of a set of several periodic sinusoidal iterations at the carrier frequency, a time difference between two consecutive iterations being higher than a period of sinusoidal iterations, and wherein a first iteration of the sinusoidal carrier signal is used to check if the first analog detection signal is above a predefined minimum threshold; a digital/analog converter connected to the generator for converting the sinusoidal carrier signal into an analog modulation signal at the carrier frequency, wherein if said first analog detection signal is below said minimum threshold, a return loop is provided for reducing said analog modulation signal; an amplitude modulator connected to the digital/analog converter and to the radiation source to modulate in amplitude the main beam at the carrier frequency by applying the analog modulation signal on said radiation source; an analog/digital converter connected to the photodetectors to convert the first analog detection signal into a first digital fluorescence signal and the second analog detection signal into a second digital reference signal; digital processing means connected to the generator and to the analog/digital converter, designed, on the one hand to process the first digital fluorescence signal by demodulation at the carrier frequency in order to calculate a first so-called fluorescence value characteristic of the amplitude of the fluorescence ray and, on the other hand, process the second digital reference signal by demodulation at the carrier frequency in order to calculate a second so-called reference value characteristic of the amplitude of the reference beam; and a means for comparing the first fluorescence value and the second reference value to calculate a final result for establishing the detection and/or quantification of the analyte.