ИСТИНА

Thermal fluctuations significantly affect the behavior of micro-scale rotating systems, as microvortexes, microbubbles in shear flow, rotating micromotors and other elements of lab-on-a-chip devices1. The influence of Brownian fluctuations on the motion of magnetic microparticles in rotating magnetic field is experimentally determined using optical tweezers technique. Numerical simulation of microparticle rotation in the presence of thermal noise are performed using Monte Carlo method. Experimental results are compared with the results of numerical simulations and the prediction of a general ”non-thermal” theory. The results show that the presence of thermal noise changes the shape of transition between uniform and nonuniform modes of microparticles rotation. In addition the coupling of translation and rotation motion of single particles was founded. This coupling often come out in form of Magnus effect, but this effect was not systematically studied at microscale. In most papers this coupling is assumed to be neglected2, but our experimental results show that this translation-rotation coupling exist and must be considered in theoretical description of microparticle motions.