Bubble-free priming of blind channels

Capillary liquid transport is an enormously powerful tool and is commonly used for directing fluids without need for any external actuation. In blind channels air pockets prevent complete capillary filling, because air cannot escape out of the channel. In this paper we present for the first time a 2-level microchannel structure, which allows complete capillary filling of blind channels without trapping air. Filling of 29 different designs with different liquids was systematically investigated by an extensive test procedure. Each design was tested at least 400 times. Certain designs showed bubble-free, successful fillings in all experiments (100% yield).