中国科学技术大学

0 Abstract 微 流 变 学 研 究 分 散 体 系 和 复 杂 流 体
Abstract
This article explores in detail the laser tweezers technology, basic concepts of microrheology and
microrheology methods by laser tweezers, with specific experiment done in disperse system and
complex fluid. Especially, we have estimated the viscosity of Brownian particle and the
viscoelastic modulus of polymer, which is replaced by water for initial evaluation. We have, in a
creative manner, discussed the interactions of two unequal sized particles, the theory of their
Brownian motion and the measurement of their viscosity.
The power spectral density (PSD) method taken in this article when estimating Brownian particles,
adds to current methods our lab employs and fill the blank of PSD’s application in viscosity
measurement. The multi-methods taken in reducing error has greatly improved experimental
accuracy. Our particularity is the improvement of PSD calculation, which not only leads to correct
estimation that previous reports did not give, but also points out the possible problems in their
estimation. We have also achieved to establish solid ground in the calculation of complex
modulus.
Key Word: Disperse system, Optical tweezers, Complex fluid, Microrheology, Viscoelastic modulus,
Power spectral density, Diffusive coefficient
0 第 一 节 光 镊 技 术 3