Abstract: A microfluidics valve comprises at least two substrates (1) between which there is at least a microchannel (5). It additionally comprises at least a barrier (4) of a meltable material, placed in the microchannel. The valve further comprises at least an optical heater (6) placed in correspondence with the barrier (4) and at least a section of one of the substrates (1), in correspondence with the optical heater (6), is transparent. The optical heater is a colored line that, when is illuminated with a light source, is heated and releases the heat to the barrier (4) thus melting the part of it that is closer to the line.