The present invention refers to medical devices comprising a modified Co-Polymer and the modified Co-Polymer itself having high flexibility and high stress resistance, especially tensile strength or tear resistance, in addition to the good physical characteristics of the known Block-Co-Polymers of a polyamide and a polyether, either polyether diol or polyether diamine. The present invention utilizes a filler insert preferably occupying a small portion of the volume of the fuel cartridge, so that the fuel cartridge may hold more fuel to ensure a long life of the fuel cartridge. Once the main supply voltage is turned off, the baseband starts a countdown period. The conducting thin film electrode is surroundsencompasses the functional layer.