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Abstract:
During the formulation of food, cosmetic, and pharmaceutical products, hydrocolloids are widely used to achieve desired rheological properties. The objective of this project is to develop a microfluidic system capable of (i) mixing formulations with different rheological properties at the microscale, and (ii) performing on-chip characterization of non-linear rheological properties at high shear rates while using small sample volumes. This approach allows the construction of ternary diagrams linking composition to rheological properties.
A theoretical framework was established to relate the volumetric flow rate and pressure drop in a straight rectangular microchannel to the viscosity of Non-Newtonian fluids, considering the Weissenberg-Rabinowitsch-Mooney correction.
The microfluidic system is fabricated using Digital Light Processing (DLP) 3D printing or Poly(methyl methacrylate) (PMMA) micromilling, pressure sensors based on technology of the Micro-ElectroMechanical Systems (MEMS) are embedded in the microchannel in order to quantify the pressure drop. Several experimental tests were conducted using this microfluidic rheometer, showing good agreement with conventional rheometry measurements.
Following validation of the system, ternary diagrams correlating composition with rheological properties were generated for starch suspension in acqueous-glycerol solutions.
Keywords: rheometry, microfluidic, mixing, hydrocolloids