This award by the Particulate and Multiphase Processes (PMP) program in the Division of Chemical, Bioengineering, Environmental, and Transport Systems (CBET, Engineering Directorate), is co-funded by the Instrument Development for Biological Research (IDBR) program in the Division of Biological Infrastructure (BIO Directorate).

Measuring the physical and mechanical properties of biological materials and other complex fluids such as polymeric liquids poses special challenges for scientists and engineers. The properties of these materials can change owing to the contact between the material and solid walls, such as the walls of a container holding the material. This collaborative project involves the development of a new device and new method to measure the rheological properties of fluids or solids that avoid contact between the sample and solid walls. The method is called acoustic tweezing rheometry, and it uses acoustic levitation to hold a small sample freely suspended in air or water while applying a force on the material that causes it to deform. The device then reads the response of the material by recording changes in the shape of the sample as a function of time. By comparing the shape of the sample with computer simulations carried out as part of the project, the rheological properties of the material can be deduced. This new instrument will find applications in a diverse array of science and engineering disciplines.

Acoustic tweezing rheometry will be used to measure properties of active polymeric and biological fluids and soft tissue without artifacts such as contamination, biological activation or gelation due to contact with solid walls. A model will be developed for noncontact measurement of material constants through analytical studies and computational simulation. The acoustic tweezing technique will be developed and validated for measurement of material properties of viscoelastic fluids. The method will be applied to biological fluids and soft tissue, including whole blood during coagulation and collagen gel. Results will be disseminated broadly, including outreach to the biological communities that could benefit from the new method.

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Tulane University
New Orleans
United States
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