Quantifying Brownian Motion in the Presence of Simple Shear Flow with Particle Diffusometry

Abstract

Particle Diffusometry, a technology derived from particle image velocimetry, quantifies the Brownian motion of particles suspended in a quiescent solution by computing the diffusion coefficient. Particle Diffusometry has been used for pathogen detection by measuring the change in solution viscosity due to the presence of amplified DNA from a specific gene target. However, Particle Diffusometry fails to calculate accurate measurements at elevated temperatures and in the presence of fluid flow. Therefore, these two current limitations hinder the potential application where Particle Diffusometry can further be used.In this work, we expanded the usability of Particle Diffusometry to be applied to fluid samples with the simple shear flow and at various temperatures. A range of diffusion coefficient videos is created to simulate the Brownian motion of particles under flow and temperature conditions. From our updated Particle Diffusometry analysis, a correction equation is formed under three different polynomial degrees of shear flow with varying flow rates and temperatures between 25 and 65 degrees. A model experiment involving the syringe pump and rectangular channel geometry provided a uniform flow for analyzing the modified algorithm. In simulation analysis, the modified algorithm successfully computes the diffusion coefficients with ± 10% error for shear rates as large as 8 pixel/Δt on all three flow types. Complementary experiments confirm the simulation results.