A microfluidic device for controlling sample introduction in microcolumn separation techniques, more particularly in capillary electrophoresis, where a sample is injected as a sample plug into a sampling device which comprises at least a channel for the electrolyte buffer and a supply and drain channel for the sample. When a call is received at a switch and an announcement is required, the announcement is played to the caller by an announcement device if the particular announcement file is stored locally. The invention also relates to inflatable airship apparatus and to a launch station for launching inflatable airship apparatus. One dependent claim, two illustrations. The first end point is closer to the feeder slot than the second end point.