Malm A V, Harrison A W, Waigh T A
School of Physics and Astronomy, University of Manchester, Oxford Rd, Manchester, M13 9PL, UK.
Soft Matter. 2014 Nov 7;10(41):8210-5. doi: 10.1039/c4sm01111b.
Optical coherence tomography velocimetry combined with a rheometer and optical modulation techniques provides increased sensitivity to the low shear rate motion of complex fluid systems. Optical modulation coupled with a new interferometer design yields improved signal to noise ratios and is demonstrated with optically opaque colloidal suspensions. Thus the measurable range of shear velocities with complex fluids can be as low as ∼40 μm s(-1), more than an order of magnitude improvement on the previous lower limit of ∼700 μm s(-1). Furthermore the apparatus demonstrates improved sensitivity to the measurement of velocity. The instrument was used to study two hard sphere colloidal systems, sterically stabilized PVP spheres of 1 μm radius and sterically stabilized polystyrene spheres of 600 nm radius, which display shear banding behavior due to shear induced concentration gradients. OCT velocimetry also allows the velocity fluctuations of the system to be quantified as a function of the distance across the rheometer gap to help classify underlying unsteady or turbulent phenomena.
光学相干断层扫描测速技术与流变仪及光学调制技术相结合，可提高对复杂流体系统低剪切速率运动的灵敏度。光学调制与新型干涉仪设计相结合，可提高信噪比，并在光学不透明的胶体悬浮液中得到了验证。因此，复杂流体的可测量剪切速度范围可低至约40μm s⁻¹，比之前约700μm s⁻¹的下限提高了一个多数量级。此外，该装置在速度测量方面表现出更高的灵敏度。该仪器用于研究两种硬球胶体系统，半径为1μm的空间稳定化聚乙烯吡咯烷酮（PVP）球和半径为600nm的空间稳定化聚苯乙烯球，它们由于剪切诱导的浓度梯度而表现出剪切带行为。光学相干断层扫描测速技术还可将系统的速度波动量化为横跨流变仪间隙距离的函数，以帮助对潜在的非稳态或湍流现象进行分类。
