Preece, D., Warren, R., Evans, R.M.L., Gibson, G.M., Padgett, M.J., Cooper, J., and Tassieri, M. (2011) Optical tweezers: wideband microrheology. Journal of Optics, 13 (4). 04402 . ISSN 2040-8978 (doi:10.1088/2040-8978/13/4/044022)
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Microrheology is a branch of rheology having the same principles as conventional bulk rheology, but working on micron length scales and microlitre volumes.
Optical tweezers have been successfully used with Newtonian fluids for rheological purposes such as determining fluid viscosity. Conversely, when optical tweezers are used to measure the viscoelastic properties of complex fluids the results are either limited to the material's high-frequency response, discarding important information related to the low-frequency behaviour, or they are supplemented by low-frequency measurements performed with different techniques, often without presenting an overlapping region of clear agreement between the sets of results. We present a simple experimental procedure to perform microrheological measurements over the widest frequency range possible with optical tweezers. A generalized Langevin equation is used to relate the frequency-dependent moduli of the complex fluid to the time-dependent trajectory of a probe particle as it flips between two optical traps that alternately switch on and off.
|Glasgow Author(s):||Gibson, Dr Graham and Warren, Ms Rebecca and Padgett, Prof Miles and Cooper, Prof Jonathan and Tassieri, Dr Manlio|
|Authors:||Preece, D., Warren, R., Evans, R.M.L., Gibson, G.M., Padgett, M.J., Cooper, J., and Tassieri, M.|
|College/School:||College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering|
College of Science and Engineering > School of Engineering > Biomedical Engineering
|Journal Name:||Journal of Optics|
|Publisher:||Institute of Physics Publishing Ltd.|