A microfluidic device, including a microfluidic network, including: a) two parallel plates each including one or more electrodes, b) at least one channel, arranged between the two plates, made from a material obtained by solidification or hardening of a material of a first fluid, and c) a mechanism varying a physical parameter of the material constituting walls of the channel so as to cause the material to pass at least from the liquid state to the solid state.