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Measuring body core temperature using a novel non-invasive sensor


In various jobs workers may be exposed to extreme environmental conditions and physical activities. Under these conditions it is imperative to follow body temperature in workers in order to protect them from overheating leading to heat related injuries. The Dräger Double Sensor (DS) is a novel non-invasive device based on heat flux balance approach for the assessment of body core temperature [1]. The purpose of this study was to compare DS measurements to rectal temperatures and to evaluate the agreement between the two measurements.


17 male subjects dressed in shorts performed the following experimental protocol: 30 min rest under thermal comfort conditions, 30 min rest under hot climate (40 °C, 40 % rh) and 60 min of exercise under the hot climatic conditions. Continuous measurements were obtained with the DS (TDS) in parallel to rectal temperature (Tre) (YSI-401 thermistor).


During rest under comfortable climatic conditions TDS tended to be lower than Tre (Figure 1). During heat exposure, mean TDS was within +0.3 °C of mean Tre. A good linear correlation (r = 0.99) between the TDS and Tre during exercise in the heat was found, which enabled to adjust TDS. A scatter plot of Temperature residuals (Tre-TDS) of the corrected data was within ±0.5 °C of mean residual (Figure 2).

figure 1

Figure 1

figure 2

Figure 2


TDS is within a reasonable range from the "gold standard" (Tre) during heat stress. It seems that TDS equilibrates slower than Tre and, therefore, the agreement between the two measurements is low during the first part of the exposure (30 minutes).


The results are promising for potential use of the DS in workers under field conditions, especially under environmental heat stress and when dressed in protective garments. Further investigations are required to validate the data under various conditions (e.g. higher heat stress).


  1. Gunga HC, Sandsund M, Reinertsen RE, Sattler F, Koch J: A non-invasive device to continuously determine heat strain in human. J Thermal Biol. 2008, 33: 297-307. 10.1016/j.jtherbio.2008.03.004.

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Correspondence to Yoram Epstein.

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Epstein, Y., Mazgaoker, S., Gruber, D. et al. Measuring body core temperature using a novel non-invasive sensor. Extrem Physiol Med 4 (Suppl 1), A28 (2015).

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