Nanointerstice-driven microflow patterns in physical interrupts

The nanointerstices (NIs) at the sidewalls of a microfluidic channel impose a strong driving force on the main flow and render the flow less dependent on the surface contact angle of the microfluidic channel. NIs facilitate rapid and stable filling of aqueous solutions in plastic microfluidic channels and have been widely applied to many commercial applications. However, the air–liquid interface in an NI-driven microflow can be disrupted by small defects in the NIs, and bubbles can form around the defects. Here, we analyze the effects of the heterogeneous contact angle and the structural interrupts on the NI-driven microflow. We also formulated a mathematical model that precisely calculated the interrupted NI-driven microflow profile. From this study, the NI-driven microflow is anticipated to further facilitate commercial applications by providing reliable microfluidic channels and offering robust NI-driven microflow with perfect initial filling, a symmetric front meniscus, and the avoidance of bubble generation.