The present invention discloses a microstructured discrimination device for separating hydrophobic-hydrophilic fluidic composites comprising particulate and/or fluids in a fluid flow. The discrimination is the result of surface energy gradients obtained by physically varying a textured surface and/or by varying surface chemical properties, both of which are spatially graded. Such surfaces discriminate and spatially separate particulate and/or fluids without external energy input. The device of the present invention comprises a platform having bifurcating microchannels arranged radially. The lumenal surfaces of the microchannels may have a surface energy gradient created by varying the periodicity of hierarchically arranged microstructures along a dimension. The surface energy gradient is varied in two regions. In one pre-bifurcation region the surface energy gradient generates a fluid flow. In the other post-bifurcation region, there is a difference in surface energy proximal to the bifurcation such that different flow fractions are divided into separate channels in response to different surface energy gradients in each of the post-bifurcation channels. Accordingly, fluids of different hydrophobicity and/or particulate of different hydrophobicity are driven into separate channels by a global minimization of the fluid system energy.
