The interfacing of a on-chip microreactor with the external world is investigated from the microfluidic point of view. A method for coupling of input and output capillaries perpendicular on the micro-reactor plane is presented. The micro-reactor consists of a planar array of 7× 7 metallic electrodes covered by a borofloat® glass reservoir provided with openings for the input and output capillaries having and internal diameter in the range of 220–500 µm on a chip of 12× 13 mm2. The reservoir has a volume of 60 µl and was manufactured by means of wet etching using a lithographically patterned Au/Cr mask. The capillaries are vertically inserted in the reservoir's openings and leaned by means of silicone rings with cylindrical and respectively conical shape, the larger of them being glued with a silicone based adhesive. The key process steps were: cutting the rings with appropriate …