Microrheology with Optical Tweezers: Measuring the solutions' relative   viscosity at a glance
  We present a straightforward method for measuring the fluids' relative viscosity via a simple graphical analysis of the normalised position autocorrelation function of an optically trapped bead, without the need of embarking on laborious calculations. The advantages of the proposed microrheology method become evident, for instance, when it is adopted for measuring the molecular weight of rare or precious materials by means of their intrinsic viscosity. The proposed method has been validated by direct comparison with conventional bulk rheology methods. 
Francesco Del Giudice, Andrew Glidle, Francesco Greco, Paolo Antonio   Netti, Pier Luca Maffettone, Jonathan M. Cooper and M...
physics.flu-dyn