Lipid bilayer at vertically aligned nanoliter droplets generated by two-layered microfluidic channels

We propose a microfluidic device for observable lipid bilayer formation between a pair of vertically aligned aqueous droplets. The device feature includes visibility of the bilayer and variable volume of the droplets, together with sub-microliter volumes of droplets and time-course observation. Referring the metering and storage modules that we recently reported, a pair of droplets was generated in symmetrical two-layered (top and bottom) channels; the droplets then moved into the storage well and contacted with each other from the top and the bottom layers. We demonstrated a bilayer formation using the device and observed crystallization of potassium ferricyanide, which was probably attributed to water permeation through the bilayer.