a sensor for detecting changes in a variety of conditions is provided , including temperature , chemical conditions including ph and ion levels , biological antigens , radiation levels , electrical field and pressure applied to the sensor . the sensor body is formed from a material which incorporates an evenly dispersed matrix of light - scattering elements . a light source emits light into the body to form an effective optical cavity in which the light is scattered by the matrix . one or more receivers detects the intensity of scattered or integrated light inside and / or outside of the optical cavity . the matrix and / or the sensor body are composed of materials which reduce or increase the density of light - scattering elements , depending on the conditions applied to the matrix . an increase in the density of the light - scattering elements results in a corresponding increase in the integrated intensity of light received by the receiver , when the receiver is positioned within the optical cavity . at a more distant location , the integrated light intensity at the receiver decreases as the density of scattering elements increases . a processing unit translates the intensity level received by the receiver , into a measure of intensity of the condition detected by the sensor .