Separation of Chiral Particles in Micro- or Nanofluidic Channels

We propose a method to separate enantiomers in microfluidic or nanofluidic channels. It requires flow profiles that break chiral symmetry and have regions with high local shear. Such profiles can be generated in channels confined by walls with different hydrodynamic boundary conditions (e.g., slip lengths). Because of a nonlinear hydrodynamic effect, particles with different chirality migrate at different speeds and can be separated. The mechanism is demonstrated by computer simulations. We investigate the influence of thermal fluctuations (i.e., the Peclet number) and show that the effect disappears in the linear response regime. The details of the microscopic flow are important and determine which volume forces are necessary to achieve separation.