Hyperspectral imaging thermometry assisted by upconverting nanoparticles: Experimental artifacts and accuracy

We combined the sensing capabilities of Er3+-doped upconverting nanoparticles (UCNPs) with hyperspectral microscopy to construct thermal images on thermally active nanostructures. Here, we studied the heat dissipation of a percolating network of silver nanowires under controlled electric current flow. We quantified the electrothermal action by analyzing the hyperspectral data and constructing 2D maps for the emission intensity, the signal-to-noise ratio, and the thermometric parameter. By studying selected clusters in the network, we concluded that the temperature is quite uniform across the film without any significant thermal gradients. Nonetheless, the thermal evolution was clearly sensed by the UCNPs when the heat dissipation due to the Joule effect was turned on and off, validating the use of this method for studying slow-dynamic thermal processes. Finally, we discuss the accuracy of the thermal readings and the systematic limitations of the proposed method.