Abstract: A device for measuring the turbidity of cerebrospinal fluid includes, a source of a light signal comprising having one or more wavelength(s), such that at least part of the emitted light signal passes through the cerebrospinal fluid; a flow element including an inlet and an outlet, the flow element being suitable for allowing cerebrospinal fluid to flow between the inlet and the outlet; an opaque element, arranged to absorb at least part of the emitted light signal after it has passed through the cerebrospinal fluid, and to allow another part of the emitted light signal to be reflected after it has passed through the cerebrospinal fluid; and an optical detector configured to detect the light signal after it has passed through the cerebrospinal fluid.