High-efficiency dielectrophoretic ratchet
2012 (English)In: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, ISSN 1539-3755, E-ISSN 1550-2376, Vol. 86, no 4, 041106Article in journal (Refereed) Published
Brownian ratchets enable the use of thermal motion in performing useful work. They typically employ spatial asymmetry to rectify nondirected external forces that drive the system out of equilibrium (cf. running marbles on a shaking washboard). The major application foreseen for Brownian ratchets is high-selectivity fractionation of particle or molecule distributions. Here, we investigate the functioning of an important model system, the on/off ratchet forwater-suspended particles, in which interdigitated finger electrodes can be switched on and off to create a time-dependent, spatially periodic but asymmetric potential. Surprisingly, we find that mainly dielectrophoretic rather than electrophoretic forces are responsible for the ratchet effect. This has major implications for the (a) symmetry of the ratchet potential and the settings needed for optimal performance. We demonstrate that by applying a potential offset the ratchet can be optimized such that its particle displacement efficiency reaches the theoretical upper limit corresponding to the electrode geometry and particle size. Efficient fractionation based on size selectivity is therefore not only possible for charged species, but also for uncharged ones, which greatly expands the applicability range of this type of Brownian ratchet.
Place, publisher, year, edition, pages
American Physical Society , 2012. Vol. 86, no 4, 041106
Other Physics Topics
IdentifiersURN: urn:nbn:se:liu:diva-118139DOI: 10.1103/PhysRevE.86.041106ISI: 000309387200003OAI: oai:DiVA.org:liu-118139DiVA: diva2:813743
Funding Agencies|Dutch Organisation for Scientific Research NWO [VDI7575]2015-05-252015-05-222015-06-04