Patent ID: 6923216

Claim:
A microfluidic device comprising: a body having at least one microscopic fluid flow channel therein, the microscopic fluid flow channel being defined by a channel wall having a fluid contact surface portion, said fluid contact surface portion comprising a substrate with a multiplicity of substantially uniformly shaped and dimensioned asperities thereon, said asperities arranged in a substantially uniform pattern, each asperity having a cross-sectional dimension and an asperity rise angle relative to the substrate, the asperities spaced apart by a substantially uniform spacing dimension and positioned so that the surface has a contact line density measured in meters of contact line per square meter of surface area equal to or greater than a critical contact line density value “Λ L ” determined according to the formula: Λ L = - P γ ⁢ ⁢ cos ⁢ ⁢ ( θ a , 0 + ω - 90 ⁢ ° ) where P is a predetermined maximum expected fluid pressure value within the fluid flow channel, γ is the surface tension of the liquid, θ a,0 is the experimentally measured true advancing contact angle of the liquid on the asperity material in degrees, and ω is the asperity rise angle; and wherein the ratio of the cross-sectional dimension of the asperities to the spacing dimension of the asperities is less than or equal to 0.1.