A simple laminated paper-based sensor for temperature sensing and imaging

We describe a low cost optical temperature sensor that is simple to manufacture. The sensor is constructed by simple soaking of paper in a solution of the temperature sensitive luminescent indicator Ru(phen)(3) and subsequent lamination of the dried paper. Lamination prevents O-2 diffusion to the indicator and thus eliminates O-2 cross-sensitivity. The temperature sensitivity was up to -2% change in luminescence lifetime per K, a t(90) response time of 10 s. Besides luminescence lifetime based measurements, the sensor is well suited for ratiometric imaging with simple RGB cameras, where the temperature dependent red luminescence can be referenced by the blue luminescence of the optical brightener in the paper. (C) 2014 Elsevier B.V. All rights reserved.