Microrheological measurement of cellulose solutions using a single particle tracking

The aim of the research was to develop microrheological measurement system to determine the alpha apparent (aapp ) and the complex shear modulus (G*(@) of microcrystalline cellulose (MCC) solutions based on a single particle tracking technique using video microscopy (VM). A micron sized particle acting as a probe in cellulose solution was tracked by a freeware called Tracker. The temporal displacement of the particle was recorded and analyzed in spectrum domain using custom-made program using MATLAB. Videos were recorded at about 30 fps depending on the recording setting resulted in output of radial frequency range from 0.4 rad/s to 10 rad/s. The results from the local measurement in cellulose solutions were compared with the bulk measurement using rheometer. Since the solution is a kind of nonhomogeneous complex material, which contained long chain fiber, the measurements were dependent on the local position of the probe in the solution. To conclude, the microrheological measurement system was successfully developed using a single particle tracking technique for the cellulose solution. The results were comparable to the common measurement using rheometer. The implication of this study suggested that local measurement in complex material solution might not give the same values of the physical quantities compared to bulk material and the local measurement technique was required sample of less than 1?L only. The developed program offers user-friendly calculation of complex shear modulus from local measurements for other kind of materials; homogenous and nonhomogeneous solutions.