MONITORING SYSTEM BASED ON ETCHING OF METALS Russian patent published in 2014 - IPC G01N33/00 

FIELD: chemistry.

SUBSTANCE: device includes an indicator having a very thin layer of metal (e.g., polyester film having an extremely thin, e.g., about one hundred Angstroms, layer of aluminium) and an activator, e.g., a reactant, such as water, water vapour, an acid, a base, oxidising agent or precursors thereof, which is capable of reacting with said indicator. The indicator retains its opacity and metallic lustre, e.g., silvery white colour, mirror like finish of aluminium layer for a long time. The activator destroys the indicator layer including the naturally formed oxide layer. The indicator layer does not have a matrix (binder). Once the device becomes transparent from being opaque, any colour, message or image printed under it become visible at a predetermined time, thus making the device self reading.

EFFECT: high accuracy and reliability of monitoring such parameters as time, temperature, time-temperature, thawing, freezing, microwave radiation, humidity, ionising radiation, sterilisation and chemicals.

25 cl, 3 tbl, 44 dwg