A simple method for making an optical temperature sensor has been developed by chemists at Strathclyde University, UK.

The team led by Andrew Mills made their sensor from a luminescent polymer film incorporating ruthenium(II) diimine which is the active species in the device.

The active species must not be sensitive to oxygen or this can interfere with temperature readings. Although the ruthenium complex used here can be affected by oxygen, this is overcome by use of poly(acrylonitrile) beads. Oxygen cannot penetrate these polymer beads and so the ruthenium complex can accurately measure temperature.

Mills says that their sensor is 'incredibly simple' to make and that it 'addresses the need for a reliable optical sensor for temperature.' Optical sensors are cheaper than more traditional electrical ones and allow remote multianalyte analysis through the use of fibre optics.

According to Mills the challenges for the future in the area of optical sensors are the need to improve selectivity and sensitivity. He says that there is a need to generate good colorimetric as well as fluorometric sensors as colorimetric sensors could be used on food packaging in supermarkets to monitor quality and allow the public to get the very best, freshest produce.  

Helen Lunn