Javier Alvarez, Nicolas1; Jeppesen, Claus3; Yvind, Kresten3; Mortensen, N. Asger6; Hassager, Ole1
1 Department of Chemical and Biochemical Engineering, Technical University of Denmark2 The Danish Polymer Centre, Department of Chemical and Biochemical Engineering, Technical University of Denmark3 Department of Photonics Engineering, Technical University of Denmark4 Structured Electromagnetic Materials, Department of Photonics Engineering, Technical University of Denmark5 Nanophotonic Devices, Department of Photonics Engineering, Technical University of Denmark6 Center for Nanostructured Graphene, Center, Technical University of Denmark
We introduce a new field-flow fractionation (FFF) technique, whereby molecules are separated based on their differential interaction (dielectrophoresis (DEP)) with optical electric fields, i.e. electric fields with frequencies in the visible and near-infrared range. The results show that a parallel array of axially non-uniform optical fields yielding an attractive potential (positive-DEP-FFF) is advantageous for the separation of polymers, biomolecules, and nanoparticles over very short distances. Furthermore, positive-DEP-FFF yields superior selectivity and resolution compared to conventional separation techniques, which do not lend themselves to miniaturization. A wide range of parameters are considered and the results are presented considering traditional chromatography parameters: the retention ratio and resolution. A simple analytical model is introduced which captures the trends for small normalized decay lengths and will be useful in the design of experimental separation platforms.