Temperature sensitivity of capillary-driven flow: application to age monitoring devices

The effects of time-dependent temperature fluctuations on surface-tension driven fluid flow inside a capillary are modeled using classical hydrodynamics. To begin, Newton's second law is evoked to derive a nondimensional equation of motion that describes the time-evolution of the fluid front position and velocity as a function of system geometry, fluid properties, and fluid temperature. This model is used to examine how temperature excursions affect the instantaneous and long-term position and velocity of the fluid front inside the capillary. Next, the effects of orientation on the movement of high viscosity fluids through a capillary are examined. From these findings, a procedure is developed for designing non-powered time-temperature integration devices for recording the cumulative temperature exposure history of an environment.