A method of producing a radiation diffractive sensor that diffracts radiation according to Bragg's law is disclosed. The sensor is produced by forming an ordered periodic array of particles on a substrate, coating the array of particles with a polymeric matrix, curing the matrix to fix the array of particles within the matrix and contacting the fixed array with an activator, wherein the activator shifts the wavelength of radiation diffracted by the sensor from a first wavelength to a second wavelength.