Abstract: A switch device includes a switch to be tested with a first terminal and a second terminal as well as a control terminal for controlling a resistance between the first terminal and the second terminal. Furthermore, the switch device includes a resistor as well as means for providing a measuring current across the resistor into the first terminal of the switch to be tested, wherein the control terminal and the first terminal of the switch to be tested are coupled in electrically conductive manner. Furthermore, the switch device includes means for sensing a voltage present due to the measuring current between the control terminal and the second terminal of the switch to be tested, wherein the voltage refers to an operability of the switch to be tested. With the switch device, in particular a greater number of potentially occurring errors of the switch to be tested can be detected as opposed to conventional switch devices.

Abstract: The invention relates to an electrochemical sensor with interdigital micro-electrodes (1) with structure widths in the sub-.mu.m range. With a twin or multi-pair array of the interdigital micro-electrodes on a substrate (8), the electrochemical detection of molecules with high sensitivity is made possible and further uses for the detection of chemical reaction cycles are made available. The electrodes may be arranged in a micro-channel applied to the substrate having a constant small volume of a few nanoliters. The electrochemical sensor of the invention is suitable for the multiple measurement of the same species of molecule or as a multi-sensitive sensor in chemical analysis and process control in various fields such as biotechnology, environmental protection or health.