A multiple-layer fiber-optic sensor is described with dual Bragg gratings in layers of different materials, so that the known temperature and strain response properties of each material may be utilized to simultaneously correct the sensor output for temperature and strain effects. A non-aqueous electrolyte containing a lithium salt, a solvent and an aliphatic mono-nitrile compound, and an electrochemical device comprising the electrolyte are also disclosed. The switch units are arranged in a matrix having multiple rows and multiple columns and may comprise instantaneous or latent space switches.