A single-channel microparticle sieve based on Brownian ratchetsElectronic supplementary information (ESI) available: Video of the separation of 3.0 m/4.3 m colloids, Materials and Methods, Fig. S1S3. See DOI: 10.1039/c2lc21089d

We present a novel device for the separation of microparticles in a single channel, which is made of inversely asymmetric Brownian ratchets. It enables separation into two different fractions with an adjustable threshold and can be modeled with good agreement. This device serves as proof of concept for an extremely compact class of microsieves. We present a ratchet-based device for particle separation in a single channel, which serves as proof of concept for a new class of compact microsieves to miniaturize analytic tasks in a wide range of applications.