A tapered electrooptic polymer waveguide interconnection structure coupling an EO polymer waveguide and a passive polymer waveguide and a method of fabricating the same. The displacer has a work piston which divides the cylinder into two work spaces. For example, fluids can be sequentially run past down a main channel to a detection zone of the microfluidic device in order to analyze the fluids. A benzothiazepine or benzothiepine compound represented by the following formula having a thioamide bond and a quaternary ammonium substitutent:.