A medical device or analytical device comprising a fluid-impervious surface comprising a base surface, at least one distinct region of the base surface covered by a mixed monolayer film, the mixed monolayer film comprising a species having a functional group M1 and a species having a functional group M2 where M1 and M2 have different surface energies, the mixed monolayer forming a surface energy gradient wherein at least one of the species used to form the monolayer on the surface comprises a biopolymer-resistant domain.