The present invention relates to a process for producing a microfluidic device which involves providing a substrate with a surface and writing a first flowable material on the surface of the substrate. The positioning mechanism includes a receiving member, a positioning member received in the receiving member, and a cover rotatable connected to the receiving member. The invention also includes an inking unit of a printing machine, which has the combination as well as a printing press having the combination. Another embodiment includes applying a lower program voltage to program memory cells of the last word line to select physical states.