The microfluidic device has a plurality of ejector elements. Each ejector element includes a first region, accommodating a first fluid flow channel and an actuator chamber; a second region, accommodating a fluid containment chamber; and a third region, accommodating a second fluid flow channel. The fluid containment chamber is fluidically coupled to the first and to the second fluid flow channels. The second region is formed from a membrane layer, from a membrane definition layer, mechanically coupled to the membrane layer and having a membrane definition opening, and a fluid chamber defining body, mechanically coupled to the membrane definition layer and having a chamber defining opening, with a width greater than the width of the membrane definition opening. The width of the membrane is thus defined by the width of the chamber defining opening.