A device for sampling a plurality of separate quantities of liquid carrying an analyte and for concentrating the analyte, the device comprising a base comprising a lower main surface and an upper main surface separated from the lower main surface by a base thickness (Tb) measured along a normal direction perpendicular to a reference plane, a plurality of discrete protrusions made of silicon jut out of the upper main surface over a protrusion height (Hp) measured along the normal direction, • wherein each discrete protrusion is topped by a porous layer comprising a top surface comprised in the reference plane, wherein, ∘ the top surface is joined to the upper main surface by peripheral walls defining the protrusion height (Hp), and ∘ the porous layer of each discrete protrusion has a porous height (hp) measured along the normal direction, which is smaller than the protrusion height (Hp) and which is preferably comprised between 5 and 90 % of the protrusion height (Hp), and • wherein the discrete protrusions are rigidly coupled to and distributed over the upper main surface, such that the top surfaces of the discrete protrusions are separated from one another by a distance (d1, d2,...) measured on the reference plane, preferably of at least 0.3 mm, and wherein • an area of each of the top surfaces is comprised between 0.25 and 50 mm 2, preferably between 1 and 35 mm 2, more preferably between 3 and 8 mm 2 and wherein, • the porous layer, ∘ comprises open pores opening at the top surface having an average pore diameter (Dp) at the top surface measured on a circle of the reference plane inscribed in each pore comprised between 1 and 5000 nm, preferably between 5 and 50 nm, more preferably 20 ± 5 nm, and ∘ has an open void volume fraction (w) defined as a volume fraction of the open pores comprised between 30 and 90 vol.%. • wherein each discrete protrusion is topped by a porous layer comprising a top surface comprised in the reference plane, wherein, ∘ the top surface is joined to the upper main surface by peripheral walls defining the protrusion height (Hp), and ∘ the porous layer of each discrete protrusion has a porous height (hp) measured along the normal direction, which is smaller than the protrusion height (Hp) and which is preferably comprised between 5 and 90 % of the protrusion height (Hp), and ∘ the top surface is joined to the upper main surface by peripheral walls defining the protrusion height (Hp), and ∘ the porous layer of each discrete protrusion has a porous height (hp) measured along the normal direction, which is smaller than the protrusion height (Hp) and which is preferably comprised between 5 and 90 % of the protrusion height (Hp), and • wherein the discrete protrusions are rigidly coupled to and distributed over the upper main surface, such that the top surfaces of the discrete protrusions are separated from one another by a distance (d1, d2,...) measured on the reference plane, preferably of at least 0.3 mm, and wherein • an area of each of the top surfaces is comprised between 0.25 and 50 mm 2, preferably between 1 and 35 mm 2, more preferably between 3 and 8 mm 2 and wherein, • the porous layer, ∘ comprises open pores opening at the top surface having an average pore diameter (Dp) at the top surface measured on a circle of the reference plane inscribed in each pore comprised between 1 and 5000 nm, preferably between 5 and 50 nm, more preferably 20 ± 5 nm, and ∘ has an open void volume fraction (w) defined as a volume fraction of the open pores comprised between 30 and 90 vol.%. ∘ comprises open pores opening at the top surface having an average pore diameter (Dp) at the top surface measured on a circle of the reference plane inscribed in each pore comprised between 1 and 5000 nm, preferably between 5 and 50 nm, more preferably 20 ± 5 nm, and ∘ has an open void volume fraction (w) defined as a volume fraction of the open pores comprised between 30 and 90 vol.%.