Cartridge for optically analyzing a biological liquid, comprising a liquid pour opening emptying into an array of channels (4, 4') which fluidly connects the opening to a plurality of vents and in which the liquid seeps by capillary action, the opening, the vents and the array of channels (4, 4') defining a plurality of analysis paths each comprising an analysis chamber, the array of channels (4, 4') comprising for each analysis path an upstream channel for fluidly connecting the opening to the analysis chamber, and a vent channel for fluidly connecting the analysis chamber to a vent, the cartridge being formed of a support having a main surface and an upper cover formed at least in part of a transparent material and also having a main surface, the upper cover and the support being assembled to one another by their main surface, at least part of the array of channels (4, 4') consisting of complementary recesses formed in part on the main surface of the support and in part on the main surface of the upper cover, each channel then being defined by a channel wall referred to as a "structured wall" provided by the support and by an opposite channel wall provided by the upper cover, the two walls facing each other and defining a channel height, the structured wall having a step, for defining either side of the step: - a first segment of the channel, in which the structured wall has a first surface energy and a first elevation defining a first height of the channel; - a second segment of the channel, in which the structured wall has a second surface energy and a second elevation defining a second height of the channel; the first height of the channel and the first surface energy of the structured wall being greater than the second height of the channel and the second surface energy, respectively; the support further comprising: - a rigid substrate having the first surface energy, the substrate incorporating a magnetic layer arranged under a non-magnetic film covering the magnetic layer; - an interlayer film having the second surface energy, said film being arranged on the substrate, the interlayer film defining part of the fluid array of the cartridge and having a cutout pattern for forming the recesses of the support and uncovering an exposed surface of the substrate, the main surface of the support consisting then of an exposed surface of the interlayer film having the second surface energy and the exposed surface of the substrate having the first surface energy. - a first segment of the channel, in which the structured wall has a first surface energy and a first elevation defining a first height of the channel; - a second segment of the channel, in which the structured wall has a second surface energy and a second elevation defining a second height of the channel; the first height of the channel and the first surface energy of the structured wall being greater than the second height of the channel and the second surface energy, respectively; the support further comprising: - a rigid substrate having the first surface energy, the substrate incorporating a magnetic layer arranged under a non-magnetic film covering the magnetic layer; - an interlayer film having the second surface energy, said film being arranged on the substrate, the interlayer film defining part of the fluid array of the cartridge and having a cutout pattern for forming the recesses of the support and uncovering an exposed surface of the substrate, - a rigid substrate having the first surface energy, the substrate incorporating a magnetic layer arranged under a non-magnetic film covering the magnetic layer; - an interlayer film having the second surface energy, said film being arranged on the substrate, the interlayer film defining part of the fluid array of the cartridge and having a cutout pattern for forming the recesses of the support and uncovering an exposed surface of the substrate, the main surface of the support consisting then of an exposed surface of the interlayer film having the second surface energy and the exposed surface of the substrate having the first surface energy.