The present disclosure relates to an arrangement for providing information about a flow rate of a fluid, comprising: a fluid inlet opening, at least one flow channel, and at least one porous zone located above the at least one flow channel, wherein the surface size and position of the at least one porous zone relative to the fluid inlet opening defines the evaporation rate of a fluid, arranged such that when a fluid is injected through the fluid inlet opening the fluid flows via hydraulic pressure through the at least one flow channel and then through the respective at least one porous zone.