Abstract: The invention concerns a device and a method for ultrasensitive detection comprising an electrically inert porous sheet sandwiched between two positively charged fine electrodes. The invention uses the capacity of the electrodes, resulting from their powerful electrostatic properties, for sensing marked antibody complexes related to antigens detected in the sample, and to leave marked antibodies non-complexed with said antigens free. The method consists in depositing a sample droplet on the porous material sheet upstream of the electrodes and in detecting downstream of the electrodes, in a signal-zone, the possible presence of an antigen-antibody complex which has diffused in the porous material. The invention is useful for detecting some millipicogrammes of antigen per milliliter of sample.

Abstract: A device for detecting the presence of substances, particularly biological materials, contained in a liquid sample is formed of a series of layers of film materials. A first film has a cut-out which forms an upper reservoir for receiving the liquid sample. A first reagent is provided in the upper reservoir capable of reacting with a substance possibly contained in the liquid sample. A first membrane is situated at the base of the upper reservoir and is made of a material which is temporarily impermeable so that the liquid sample is temporarily retained in the upper reservoir in contact with the first reagent, but after awhile the membrane becomes permeable and allows the liquid to pass. A second film has a cut-out which forms a median reservoir positioned for receiving the liquid passing through the first membrane. A second reagent is provided in the median reservoir capable of reacting with a predetermined substance.

Abstract: A device for the rapid qualitative and quantitative determination of the presence of a reactive ligand in a fluid.This device comprises a first reaction zone in which there is an at least temporarily impermeable membrane designed to receive a sample of test fluid and to be associated with at least one labeled reagent; a second reaction zone which is bounded on the one hand by the said membrane and on the other by a second at least temporarily impermeable membrane comprising a solid phase containing a reference reagent; and a third reaction zone which contains means for developing the reaction.A method for the rapid qualitative and quantitative determination of the presence of a reactive ligand in a fluid.Applications to the detection of the presence, in a biological fluid, of antibodies or antigens in particular.