The current study presents experiments for the initial stages of fluidization induced by a localized fluid injection. The process was studied by recording high-speed videos in a 2-D-region far from the boundaries using Planar Laser Induced Fluorescence and Refractive Index Matching. The experimental setup allowed for several parameters to be systematically studied including particle sizes, initial bed heights, and injection port diameters. The results show that the critical flow rate required for fluidization is primarily dependent on the initial height of the granular bed. However, this dependence is not a linear relation but progressively plateaus for larger heights. Conversely, the diameter of the chimney relates only slightly to the injection port diameter and significantly more to the diameter of the particles. (c) are average of the video sequence; (d), (e), and (f) are standard deviations of the video sequence. (a) and (d) are of a static bed, (b) and (e) show a bed with a fluidized cavity and pictures (c) and (f) show a chimney. Figure (d) is solid black indicating no movement and resulting zero standard deviation. Image processing done by ImageJ. 37 Solid symbols are for the injection port of D 5 10 mm and open symbols are for D 5 40 mm. Symbols are as follow: Circles, 3 mm particles; squares, 5 mm; triangles, 7 mm; hexagon, 10 mm. [Color figure can be viewed at wileyonlinelibrary.com]

A continuous microfluidic viscometer is used to measure blood coagulation. The viscometer operates by flowing oil and blood into a cross section where droplets are generated. At a set pressure, the length of the droplets is inversely proportional to the viscosity of the blood sample being delivered. Because blood viscosity increases during coagulation as the blood changes from a liquid to a solid gel, the device allows to monitor coagulation by simply measuring the drop length. Experiments with swine blood were carried out in its native state and with the addition of coagulation activators and inhibitors. The microfluidic viscometer detected an earlier initiation of the coagulation process with the activator and a later initiation with the inhibitor compared to their corresponding controls. The results from the viscometer were also compared with the clinical method of thromboelastography (TEG), which was performed concurrently for the same samples. The time to initiation of coagulation in the microfluidic viscometer was correlated with the reaction time in TEG. Additionally, the total time for the measurement of clot strengthening in TEG correlated with the time for the maximum viscosity observed in the microfluidic viscometer. The microfluidic viscometer measured changes in viscosity due to coagulation faster than TEG detected the clot formation. The present viscometer is a simple technology that can be used to further study the entire coagulation process.

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A unique glass etching process creates variable height channels capable of separating particles or cells by size or deformability.