An apparatus and method to segregate particles suspended in a fluid with an obstacle field in the flow path of the fluid. The particles may be dispersed after an interaction with obstacles in the obstacle field. The obstacle-particle interactions may result in an asymmetrical particle shift or bump in which the particles are differentially dispersed relative to the obstacle and the fluid flow. Individual obstacles having properties that are asymmetrical are arranged creating asymmetrical gaps between adjacent pairs of obstacles to separate particles flowing through the device.