The colour change reaction that darkens Reactolite glasses has been applied to optically sensing amino acids and metals by chemists at Dublin City University, Ireland. 

A research team led by Dermot Diamond have developed a re-useable optical sensor, by coating a support surface with optically sensitive molecules, spiropyrans. The sensor can be switched on by exposure to UV light, allowing metal cations or amino acids to bind to its surface. In this state, the spiropyran is purple and optical measurements can be taken. The sensor is switched off by exposure to visible light, which returns the spiropyran to its original state.

Having established a basic, yet highly reproducible chemical sensor, the team say they intend to widen their sensing capabilities to more complex molecules and greater sensitivities.

Merlin Fox