Calibration uncertainty of MEMS thermopile imagers for quantitative temperature measurement

This article presents the calibration procedure of three MEMS thermopile imagers from the same manufacturer. We did not find in the literature a study that put the accuracy of these sensors to the test. We divided the methodology into the following parts: data collection, mathematical modeling (radiation heat transfer, non-uniformity correction, and regression models), estimation of uncertainty sources, and expanded uncertainty. The Guide to the Expression of Uncertainty in Measurement was the base of our uncertainty estimations. We considered the flat plate radiator, the radiation heat transfer model, the correction model, and the IR sensors as uncertainty sources. The coefficients ABC (Sakuma-Hattori model) and RBF are considered dependent variables in the regression models (we did not calculate ABC or RBF using the half-width and the operating wavelength range). Results led to a maximum deviation of 0.46 degrees C in the RBF model and 0.49 degrees C in the Sakuma-Hattori model. Uncertainties related to the flat plate radiator, mainly uniformity and temperature, were dominant in the uncertainty budget, followed by the mathematical routines and temporal noise. Finally, we compared our expanded uncertainties with the scientific literature and the manufacturer's estimations. The proposed methodology resulted in a minor expanded uncertainty, compared to the uncertainty provided by the manufacturer. One of the three MEMS thermopile imagers presented pixels with relatively high expanded uncertainty, which illustrates the importance of a pixel-by-pixel analysis. Readers from this journal can benefit from this article as an alternative to check the reliability and accuracy of infrared thermometers..