Development of non-contact rheometry for measuring rheological properties of biological fluids - ABSTRACT/SUMMARY
Background: Rheological properties of biological fluids are closely linked with various physiological
processes. For example, disorders of blood viscosity are significantly associated with the progression of
coronary heart disease, peripheral artery diseases, stroke and hyperviscosity syndromes. The surface tension
of mucus is influenced by pathological processes in the lungs. While rheological properties of fluids are
important biomarkers critical to diagnose and evaluate progression of diseases, rheometry instruments have
been primarily developed for industrial applications. Existing rotational-based and tube-based rheometry
devices are not capable of measuring both surface tension and viscosity of fluids. Additionally, there are
various drawbacks of current rheometry instruments for measuring viscosity and methods for measuring
surface tension such as the need for contacting samples, necessitating highly skilled operators, and cleaning
the testing chamber between each sample.
This project aims to address these unmet and critical needs by developing a non-contact rheometry
method for measuring biological fluid surface tension and viscosity using small volume samples (thin-
layer fluid).
Methods: We will utilize ultrasound as an excitation source or “acoustic indenter” to generate a propagating
capillary wave on the surface of the fluid and use optical coherence tomography (OCT) as a measurement
device to precisely record particle displacements of wave motion. With this experimental approach, the sample
in a Petri dish is never in direct contact with any part of the measurement apparatus. Our previous work has
utilized capillary waves in a deep fluid regime to measure surface tension and viscosity. We will build on this
previous work to extend the theoretical model into the thin-layer fluid case, capillary waves in a shallow fluid
regime, in a similar non-contact fashion. We will optimize the proposed rheometry method to achieve
measurements with high accuracy and precision for thin-layer measurements.
To accomplish the goals of this project we propose these Specific Aims:
• Aim 1) Construct and validate the theoretical model for rheological properties in the shallow
fluid case.
• Aim 2) Optimize the rheometry acquisition method and signal processing to yield robust results
in thin fluid layers.
Impact: The proposed technique will carry out measurements with the following advantages including being
non-contact, fully automated, fast, and not needing cleaning between tests, which provides a biology-friendly
environment.
