FIG. 1.

A proposed microfluidic-based measurement method to detect the elevated erythrocyte aggregation of diabetic blood. (a) Schematic of the measurement system composed of a microscope equipped with CMOS camera, microfluidic device, and LED illumination system. A delay generator synchronizes the trigger signals of the CMOS camera and the LED system. (b) Data processing procedure. A micro-particle image velocimetry (PIV) technique is applied to four consecutive flow images acquired at a high frame rate (Δt_Frame = 0.2 ms) to measure velocity fields. By adjusting trigger signals, the image acquisition process is repeated with a frequency of 2 Hz (Δt_Triger = 0.5 s) for a total time (t_F) of 180 s. Time-averaged mean velocity field and intensity map are used to minimize adverse errors. (c) Procedure to calculate the average size of speckles in an image of 128 × 128 pixels in size. The horizontal and vertical profiles are calculated by using the normalized autocovariance function (f_Auto). The full width at half maximum of f_Auto provides the size of speckle pattern. The average speckle area (A_Speckle) is evaluated by multiplying the horizontal and vertical speckle sizes. (d) Temporal variation of light intensity along the channel width. Speckle patterns are clearly appeared in the channel with the lapse of time. (e) Variations of A_Speckle and the injection flow rate (Q) of the syringe pump. The flow rate is decreased from 1 to 0 ml/h to induce EA formation.