Micro-chamber filling experiments for validation of macro models with applications in capillary driven microfluidics

Abstract

Prediction of bubble formation during filling of microchambers is often critical for determining the efficacy of microfluidic devices in various applications. In this study experimental validation is performed to verify the predictions from a previously developed numerical model using lumped analyses for simulating bubble formation during the filling of microchambers. The lumped model is used to predict bubble formation in a micro-chamber as a function of the chamber geometry, fluid properties (i.e. viscosity and surface tension), surface condition (contact angle, surface roughness) and operational parameters (e.g., flow rate) as user defined inputs. Several microchambers with different geometries and surface properties were microfabricated. Experiments were performed to fill the microchambers with different liquids (e.g., water and alcohol) at various flow rates to study the conditions for bubble formation inside the microchambers. The experimental data are compared with numerical predictions to identify the limitations of the numerical model. Also, the comparison of the experimental data with the numerical results provides additional insight into the physics of the micro/nano-scale flow phenomena. The results indicate that contact angle plays a significant role on properties of fluids confined within small geometries, such as in microfluidic devices.