The research interests of the Mills group are wide and varied including: dye and semiconductor photochemistry, redox catalysis (in particular, oxygen catalysis), solar energy conversion (in particular artificial photosynthesis) and colour and fluorescence based indicators and smart inks and plastic films.
The group has created a smart, oxygen sensitive ink, which is activated (photobleached) upon a short exposure to UVA light. In the absence of oxygen the ink stays bleached, but in its presence it recovers its original colour at a rate which is proportional to the ambient level of oxygen. The attached movie (http://www.youtube.com/watch?v=uhWog0X-C0E) shows such an ink being photobleached in air and then recovering its original colour. In the second movie (http://www.youtube.com/watch?v=EJhGTf0UEuM) a piece of tape has been attached on the ink to ensure the absence of the oxygen and to show that the indicator stays photobleached in such an environment. Currently, Lucie Nemcova is exploring exploring ways to alter the response time of this indicator from a few hundred seconds to days, by varying the encapslatiing medium. Such indicators have potential in any application where the presence or absence of oxygen is essential, such as in modified atmosphere packaging.
S-K. Lee, A. Mills and A. Lepre. An Intelligence Ink For Oxygen, Chem. Commun., 1912-1913, 2004.
During a recent trip to Prague to attend the SP4 meeting on semiconductor photochemistry we found we had run out of time and needed to produce a 3 min movie for an imminent pitch for funding our photocatalyst work through InkIntelligence. So, during the conference AM went out with Christopher O’Rourke and David Hazafy and filmed various parts, in the pouring rain, in different parts of Prague. This movie was filmed on an iPhone and the sound was recoded on a separate iPhone, in AM’s top pocket; Chris O’Rourke put it all together. Needless to say – we were all soaked at the end – but we did get through to the next round!
Mills group member Katherine Lawrie visited a research group at the University of Cadiz, Spain, as part of a collaboration aimed at creating a colourimetric UV dosimeter for solar water disinfection (SODIS). We want to develop a device which tells users of the SODIS method (typically those in third world countries) when a bottle has been exposed to sufficient amounts of sunshine and the water is safe for drinking.