Brownian motion: absolute negative particle mobility.
Noise effects in technological applications, far from being a nuisance, can be exploited with advantage - for example, unavoidable thermal fluctuations have found application in the transport and sorting of colloidal particles and biomolecules. Here we use a microfluidic system to demonstrate a paradoxical migration mechanism in which particles always move in a direction opposite to the net acting force ('absolute negative mobility') as a result of an interplay between thermal noise, a periodic and symmetric microstructure, and a biased alternating-current electric field. This counterintuitive phenomenon could be used for bioanalytical purposes, for example in the separation and fractionation of colloids, biological molecules and cells.
Ros
Alexandra
A
Experimental Biophysics & Applied Nanosciences, Bielefeld University, 33501 Bielefeld, Germany. dra.ros@physik.uni-bielefeld.de
Eichhorn
Ralf
R
Regtmeier
Jan
J
Duong
Thanh Tu
TT
Reimann
Peter
P
Anselmetti
Dario
D