Optothermal molecule trapping by opposing fluid flow with thermophoretic drift

Stefan Duhr and Dieter Braun

Physical Review Letters
2006 vol: 97 issue: 038103 doi: 10.1103/PhysRevLett.97.038103


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.

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Topics: Monolith – MicroScale Thermophoresis, MST, Proteins, Publications