As shown in figure 2 the copper-coated polyimide flex board is rolled up to enable the concentric alignment of
the electrodes to the tube shaped measuring cell. Electrodes are inserted into the PMMA alignment block to
guarantee a concentric adjustment of measuring cell and electrodes. In a last step a commercially available silicone
tube (ID = 2.5 mm, WT = 0.2 mm, L = 5 mm) acting as measuring cell is inserted and attached by glue to the
alignment block, whereby the electrodes and the tube are not in contact (see cross section view in fig. 2).