Procter and Gamble Co. 1 article published in JoVE Engineering Combining Microfluidics and Microrheology to Determine Rheological Properties of Soft Matter during Repeated Phase Transitions Matthew D. Wehrman1, Melissa J. Milstrey1, Seth Lindberg2, Kelly M. Schultz1 1Department of Chemical and Biomolecular Engineering, Lehigh University, 2Process and Engineering Development, Procter & Gamble Co. We demonstrate the fabrication and use of a microfluidic device that enables multiple particle tracking microrheology measurements to study the rheological effects of repeated phase transitions on soft matter.