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The lifetime of silicon detectors in I severe radiation environment at CERN LHC depends strongly upon careful detector design and material selection, due to the anticipated radiation-induced damage. We fabricated recently more radiation-tolerant CMS forward pixel sensorsi with new designs of silicon pixel detectors with the n+/n/p+ and doublesided multiguard ring structure. Electrical characterization of such devices was performed before and after irradiation to neutron fluences (1 MeV equivalent) up to 6x1014 n/cm2, measuring leakage current, potential distribution over the guard rings and full depletion voltage. Studies on the radiation hardness using oxygen-enriched silicon substrates are being presented separately [l].