Medical engineering is one example in which graphite materials constitute the material of choice not on account of their high temperature stability or because of their tribological properties. In dialysis measuring cells graphites are used as impermeable electrodes which are characterized by their physiological purity which is due to their good chemical stability and inertness in addition to their high purity and impermeability for ions. Moreover, the electrical conductivity of these materials can be adjusted well and over a long period of operation.