title: Optothermal molecule trapping by opposing fluid flow with thermophoretic drift.
abstract: Thermophoresis moves molecules along temperature gradients, typically from hot to cold. We superpose fluid flow with thermophoretic molecule flow under well-defined microfluidic conditions, imaged by fluorescence microscopy. DNA is trapped and accumulated 16-fold in regions where both flows oppose each other. Strong 800-fold accumulation is expected, however, with slow trapping kinetics. The experiment is equally described by a three-dimensional and one-dimensional analytical model. As an application, we show how a radially converging temperature field confines short DNA into a 10 microm small spot.
authors.affiliation: Biophysics, Ludwig Maximilians Universität München, Amalienstrasse 54, 80799 München, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Duhr
authors.forename: Dieter
authors.initials: D
authors.lastname: Braun
mesh_terms: D004247:DNA / Q000737:chemistry*; D004586:Electrophoresis / Q000379:methods; D007700:Kinetics; D046210:Microfluidic Analytical Techniques / Q000379:methods*; D008856:Microscopy, Fluorescence / Q000379:methods; D008954:Models, Biological; D013696:Temperature
chemical_list: D004247:DNA