Tobias Thalheim, Marco Braun, and Frank Cichos
Peter Debye Institute for Soft Matter Physics, Leipzig University, Linnéstr. 5, 04013 Leipzig
We report on single DNA molecules in liquids trapped over several minutes applying a feedback-driven dynamic temperature field. The thermophoretically induced drift velocities, which make the trapping of single nano-objects possible, are generated by spatially and temporally varying the temperature at a plasmonic nano-structure. The randomization of the positions and conformations by Brownian motion is prevented with the help of feedback-controlled switching of local temperature fields. A model-free statistical tool called principal-components analysis as introduced by Cohen & Moerner  is employed to assess the distortion of the DNA’s conformation and conformation dynamics.
 A. E. Cohen, and W. E. Moerner, PNAS 104 (31), 12622-12627 (2007). (link)