A polymeric hollow nanoshell or nanosphere for release of an agent is described, wherein the hollow nanosphere comprises at least one biodegradable polymer, characterised in that the polymer is cross-linked. This makes it possible to shorten the rise time of an output voltage and to reduce the maximum current at start-up. Fuel injection arrangement with a coupling device and an injection valve which is coupled to the coupling device. The top and bottom electrodes may be TiNTi, PtTiNTi, InTiNTi, PtRhOx compounds, or PtIrOx compounds.