A device and a method for sensing the conductivity of a fluid

A device and a method for sensing the electrolytic conductivity of a fluid are disclosed. The device comprises a battery (1) having an oxidizing electrode (2) and a reducing electrode (3) connected by a hydrophilic and/or a porous material or an empty receptacle (4) providing a microfluidic cavity for a fluid (10), said battery (1) being activated upon the addition of said fluid (10) therein and providing electrical energy while the fluid (10) impregnates by capillarity said microfluidic cavity; and at least one instrument (5) connected to the battery (1). The instrument (5) has an equivalent impedance that makes the battery (1) work at a specific operating point allowing determining or discriminating among values of electrolytic conductivity of the fluid (10) and includes means for quantifying the electrolytic conductivity of the fluid (10), thereby inferring the conductivity of the fluid (10) from the performance of the battery (1).