Biomedical Sensors and Subsystems

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Microrheometers for Simple and Complex Fluids
Eric Livak-Dahl and Mark A. Burns
New (left) and old (right) designs for microfluidic viscometers
New (left) and old (right) designs for microfluidic viscometers

The rheological properties of blood, such as viscosity and viscoelasticity, have been associated with a number of adverse cardiovascular conditions including stroke and hypertension. Other biological fluids such as protein solutions, sputum, nasal and cervical mucus, and synovial fluid can also be analyzed on the basis of their viscosity. While devices exist to measure these properties, most are bench-top instruments that can only be used in a laboratory setting. A microfabricated device, which could be used by a medical practitioner as a point-of-care device to quickly and easily measure the viscous and viscoelastic properties of the patient’s blood or other samples would be a very useful tool. We have already developed microscale devices to measure the viscosity of Newtonian fluids and the parameters of the power law model. We are presently working on developing devices that would measure the viscoelastic properties of samples, as well as nanoliter-volume droplet-based devices for probing samples over a wide range of shear rates, concentrations, and temperatures.

Updated 06/13/2011