Paper Number
PO14 

Session
Poster Session

Title
Simultaneous characterization of thermophoresis and fluid properties using multiple particle tracking microrheology

Presentation Date and Time
October 13, 2021 (Wednesday) 6:30

Track / Room
Poster Session / Ballroom 1-2-3-4

Authors (Click on name to view author profile)

  1. Roffin, Maria C. (Lehigh University, Department of Chemical and Biomolecular Engineering)
  2. Cheng, Xuanhong (Lehigh University, Bioengineering, Materials Science & Engineering)
  3. Schultz, Kelly M. (Lehigh University, Chemical and Biomolecular Engineering)
  4. Gilchrist, James F. (Lehigh University, Department of Chemical and Biomolecular Engineering)

Author and Affiliation Lines (in printed abstract book)
Maria C. Roffin1, Xuanhong Cheng2, Kelly M. Schultz1 and James F. Gilchrist1
1Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, PA 18015; 2Bioengineering, Materials Science & Engineering, Lehigh University, Bethlehem, PA 18015

Speaker / Presenter 
Roffin, Maria C.

Keywords
microfluidics; rheology methods

Text of Abstract
Thermophoresis is the phenomenon that particles in a fluid migrate in a temperature gradient. Until now, no agreement has been found on the underlying physics of thermophoresis, however applications utilizing thermophoresis are numerous. A particularly important application is bioseparations. The work presented here characterizes fluids in a microfluidic device to simultaneously measure thermophoresis of dispersed fluorescent tracer particles and rheological properties of the continuous phase using multiple particle tracking microrheology (MPT). MPT measures the Brownian motion of the embedded probe particles and relates this to rheological properties. We develop a method to characterize the unidirectional motion induced by a 1D thermal gradient (parallel to the channel walls) and at the same time, perpendicular to the thermophoretic motion, tracer particles undergo independent Brownian motion, enabling MPT. Using MPT, the one-dimensional particle mean-square displacement is measured enabling the calculation of the diffusion coefficient and the temperature-dependent fluid viscosity. The thermophoretic motion is characterized by quantifying particle velocity and calculating the thermal diffusion coefficient. A better understanding of the relationship between thermophoresis and material properties will allow for optimization of microfluidic devices designed for effective and efficient bioseparations. A timely application is the advancement of devices used for viral diagnostic tools, enabling the implementation of thermophoretic enrichment methods for virus detection.