TECHNICAL FIELD OF THE INVENTION

The present invention relates to a microfluidic system, more particularly to the architecture of a chamber located in a device of the system and intended for the implementation of an amplification reaction.

RELATED ART

The qPCR reaction consists of amplification of a targeted DNA or RNA sequence (representative of a particular organism) coupled to an intercalator or a probe producing a fluorescence that can be detected by an optical apparatus if this sequence is amplified. Thus, an increase in fluorescence means that the amplification reaction is taking place and that the DNA or RNA of the target organism was in fact present. If there is no reaction, however, it must be clear that this is due to the absence of the target organism and not to the inhibition of the amplification reaction, which would result in a false negative. The enzymes responsible for the amplification reaction are indeed sensitive to many inhibitors provided by the sample being tested.

To ensure that the absence of amplification means the absence of the target, internal reaction controls are used. These are most often another DNA target added intentionally to the test that will be amplified simultaneously with the sample of interest. It is then necessary to be able to discriminate between the two reactions. Several strategies are used in the industry:One could be to use part of the sample to carry out the control in parallel, as an independent reaction. This requires splitting the initial sample, resulting in a loss of sensitivity/representativeness of the test. The advantage is that it is possible to use any amplification detection technique for this control (fluorescent DNA intercalation, for example).In order not to split the sample, another strategy consists in performing the control in the same reaction as the target sequence. This solution allows testing of the entire sample but is not compatible with all detection techniques, notably with the use of non-specific intercalating agent, a sequence or any other non-sequence-specific detection mode (colorimetry, pH-metry . . . ).

Patent application EP0586112A2 and U.S. Pat. No. U.S. Pat. No. 6,312,930B1 each describe a detection method for eliminating false negatives, by adding a control target.

The invention therefore aims to provide a microfluidic system equipped with an integrated solution to control the amplification reaction or to identify several targets during the same analysis.

DISCLOSURE OF THE INVENTION

This aim is achieved by a microfluidic system intended for the analysis of a biological sample containing biological species, said system comprising:An optical detection device comprising a source configured to emit an optical signal and at least one sensor having a capture surface defining an optical signal reading zone,A microfluidic device which comprises:A support in which a so-called amplification chamber, in which an amplification reaction can be carried out, is made,An input channel opening into said amplification chamber,The amplification chamber comprising at least one first zone located in the sensor reading zone and at least one protuberance forming a recess intended to receive a compound for internal control of the amplification reaction and arranged to be located outside the sensor reading zone or configured to be opaque to said optical signal.

According to one feature, the amplification chamber comprises a first volume having a first section and a second volume having a second section narrowed with respect to said first section so as to form a protuberance, said protuberance forming said recess.

According to another feature, said support comprises several superimposed strata and said amplification chamber is made by at least two of said superimposed strata, called upper stratum and lower stratum, said recess is made in only one of said two strata.

According to another feature, said protuberance forming said recess is made in the lower stratum.

According to another feature, the amplification chamber comprises a main cavity made in the upper stratum and one or more secondary cavities made in the lower stratum and each forming another recess of said chamber.

According to another feature, the internal reaction control compound contains a known DNA sequence or set of DNA primers targeting a predefined DNA target, allowing its amplification according to the amplification method used.

According to another feature, the first zone of the chamber is transparent to allow an optical signal supplied by a source of the detection device to pass through and the second zone has at least one opaque portion configured not to allow said optical signal to pass through.

The invention also relates to a method for analyzing a biological sample containing biological species, said method being implemented by a system as defined above and consisting in:Placing an internal reaction control compound in the recess of the amplification chamber,Injecting a fluidic sample into the amplification chamber of the microfluidic device,Detecting with the sensor the presence of a target compound contained in said fluidic sample and located in the first zone of the amplification chamber,Detecting, with a time lag, the presence of the internal reaction control compound in the first zone of the amplification chamber.

