Alternatively, a thin-film deposition of metal by sputtering or evaporation through a shadow mask has been carried out. Figure 4 shows a schematic drawing of the chip including al relevant dimensions, Fig. 5 an actual photograph of the chips, the top chip with carbon electrodes, the lower one with silver electrodes. The separation channel has the dimensions 50 μm width and 50 μm in height, with a separation length of 75 mm. The electrodes have a design width of 200 μm with an electrode gap for measuring of 250 μm. A microscopy image of screen-printed electrodes can be seen in Fig. 6a, an equivalent image of the thin-film electrodes is shown in Fig. 6b. It is important to notice that despite the purely manual optical alignment of the chip and the cover lid containing the electrodes with alignment marks, the alignment accuracy is of the order of 10 μm. Furthermore, despite of the comparatively large thickness of the screenprinted electrodes (4-5 μm), the cover lid could be sealed completely without voids on top of the channel.