TECHNOLOGY FOCUS - BIOLOGY - Preferred Microbes: The microbes are Pseudomonas sp. or Zymomonas sp.. The microbes maintain viability for one week at 4 degrees C, and further capable of producing metabolites (preferably ethanol). In the method (M3), the microbes comprise members of the genus Shewanella. In the method (M4), the microbe is selected from strains of the genera Lactobacillus (preferably Lactobacillus acidophilus, Lactobacillus casei and Lactobacillus bulgaricus), Bifidobacterium, Streptococcus thermophilus and Saccharomyces boulardii.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: In (M1), the redox system comprises persulfate salt (preferably ammonium persulfate), ferrous sulfate and ascorbic acid.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: In (M1), the liquid polyol is glycerol or sugar alcohol (preferably xylitol, mannitol or lactitol).    TECHNOLOGY FOCUS - POLYMERS - Preferred Fiber: The crosslinked electrospun hydrogel fibers comprise polyethers. The polyethers comprise polyethylene and/or polypropylene oxide, co-polymers (preferably triblock copolymer of polyethylene oxide-polypropylene oxide-polyethylene oxide)), triblock copolymer and/or polyethylene oxide, F127-DMA (RTM: polyoxyethylene-polyoxypropylene-polyoxyethylene triblockpolymer) and/or polyethylene oxide, glycosaminoglycans (preferably functionalized hyaluronic acid) or proteins, where the polyethers are functionalized with terminal acrylate or methacrylate groups, and have diameters of 0.6-5 microns. Preferred Method: In the method (M1), the electrospun hydrogel fibers are crosslinked by contacting the electrospun hydrogel fibers with a crosslinking agent in a liquid polyol, where the liquid polyol (70%, preferably 60%, especially 30%) is replaced with water, and the electrospun hydrogel fibers are crosslinked by contacting the electrospun hydrogel fibers with redox system that produces a free radical inhibitor in a solvent that comprises a liquid polyol and optionally water. In the method (M2), the act of crosslinking comprises treating the electrospun fibers with redox system, where the liquid polyol (70%) is replaced with water. Preferred Biosensor: In the biosensor (B1), the signal is an electric signal. EXAMPLE - No suitable example given.