TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Fibres: The fibres have a diameter of 10 nm to 1 micron, a dielectric constant of below 4 and an outer wall which is preferably multi-layered. They also have a core, especially made from inorganic compounds, ceramic fibres, carbon fibres, polymers and/or metals, which is spaced 10-300 nm from the outer wall. The outer wall is made from various polymers, a metal or (glass) ceramics.Preferred Process: The degradable material is removed by a thermal, chemical, biological, ray-induced or photochemical method or using plasma, ultrasound or solvent extraction.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - The outer wall of the hollow fibres is made from a metal of Group Ia, Ib, IIa, IIb, IIIa, IIIb, IVa, IVb, Vb, VIb, VIIb and/or VIIIb (as such or as an alloy) or from SiOx, perovskite, aluminum oxides or zirconium oxides. The core present in the hollow fibres is made from inorganic compounds, carbon fibres and/or metals.    TECHNOLOGY FOCUS - POLYMERS - The outer wall of the hollow fibres is made from poly(p-xylene, polyacrylamide, polyimides, polyesters, polyolefins, polycarbonates, polyamides, polyethers, polyphenylene, polysilanes, polysiloxanes, polybenzimidazoles, polybenzthiazoles, polyoxazoles, polysulfides, polyester amides, polyarylenevinylenes, polylactides, polyether ketones, polyurethanes, polysulfones, ormocerene, polyacrylates, silicones, fully aromatic copolyesters, poly-N-vinylpyrrolidone, polyhydroxyethyl or polymethyl methacrylate, polyethylene or polybutylene terephthalate, polymethacrylonitrile, polyacrylonitrile, polyvinyl acetate, neoprene, buna N, polybutadiene, polytetrafluoroethylene, modified or non-modified cellulose, alginates or collages or their homo- or copolymerisates and/or blends. The core present in the hollow fibres is made from polymers.    TECHNOLOGY FOCUS - CERAMICS AND GLASS - The outer wall of the hollow fibres is made from glass, glass ceramics or ceramics. The core present in the hollow fibres is made from ceramic fibres. EXAMPLE - A 5% solution of poly-L-lactide in CH2Cl2 was spun in a 35 kV electrospin apparatus (diameter of cannula tips = 0.3 mm; distance from glass substrate plate = 10 cm). The resulting polylactide template fibres were placed in a gas phase separator and (2.2)paracyclophane (230 mg) was introduced as a vapor at 2200 C/1 mbar and then pyrolyzed at 800 degrees C to form poly(p-xylylene). The poly(p-xylylene)/polylactide composite obtained was heated at 275 degrees C/0.01 bar for 8 hours to give poly(p-xylylene) hollow fibres with an internal diameter of 0.1-2 micron and a density of 0.15 g/cm3.