“Fluid Mechanics of Thin Liquid Films: From Viscosity Measurement to Biomedical Devices”

Speaker: Mahesh S Tirumkudulu, Ph.D.

Abstract

We describe a unique method to measure the viscosity of liquids based on the fluid mechanics of thin films. A drop of the sample is spread over a substrate by contacting the drop with a blade and moving the blade across the substrate. The film thickness is determined by the capillary number, which measures the competition between the viscous force that smears the liquid over the glass slide and the surface tension that resists the deformation of the interface. We show that the smear length for a fixed sample volume is also determined by the capillary number and can serve as a reliable measure of fluid viscosity. The technique is rapid, requires only a drop of sample, and can measure over a wide range of viscosities (1-10,000 cP). We apply the technique to measure blood viscosity and show that viscosity below a threshold, due to low hematocrit, indicates severe anemia, while a significant increase in viscosity, due to red blood cell stiffening upon blood deoxygenation, is a marker for sickle cell disease (SCD). Our method exhibits exceptional sensitivity in detecting severe anemia and SCD based on smear lengths, rivaling that of commercial screening devices. A decrease in viscosity in SCD patients undergoing drug therapy enables effective monitoring and personalized medicine, a feature unique to the proposed test.

Speaker Bio

Mahesh S Tirumkudulu is the Larsen & Toubro Chair Professor and Chair of the Department of Chemical Engineering at the Indian Institute of Technology Bombay in Mumbai. He obtained his Bachelor's degree in Technology from IIT Madras in 1995 and his PhD (with Dr. Andreas Acrivos) from the City University of New York, USA, in 2001. He joined IIT Bombay in 2003 after a Postdoctoral stint at Princeton University (with Dr. William Russel). Prof Tirumkudulu works in the area of fluid mechanics and colloids & interfaces with a focus on research problems related to paints & coatings, atomization with applications to combustion and sprays, and biomedical devices. The research from his lab has recently been commercialized through a startup, Rheoheme Private Limited (https://www.rheoheme.com/), which specializes in biomedical and materials characterization.