Study of Thermocouples as Skin Thermometers

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Abstract
The precision of thermocouple readings of skin temp. was compared with radiometer readings made under identical circumstances. The pressure of the thermocouple wire against the skin, the enviromental conditions, and method of attachment of the thermocouple wires to the skin were altered to observe their influences. Pressure of the thermocouple against the skin, sufficient to produce a stable temp. reading, increased skin temp. by as much as 2[degree]C. It was concluded that methods of application requiring appreciable pressure are unsuitable for the measurement of skin temp. During infrared irradiation of the skin the thermocouple itself was heated. Comparisons of radiometric and thermocouple measurements of average skin temp. under normal, hot and cold environmental conditions indicated that the no. 28 gauge bare junction thermocouple gave values within [plus or minus] 0.6[degree]C of the radiometer readings under all conditions; the no. 28 gauge thermocouple applied to the skin with adhesive tape covering the junction yielded deviations which were twice as great; and the no. 40 gauge bare junction thermocouple was unsatisfactory because of its fragility and the difficulty of obtaining thermal contact. Of these instruments the no. 28 gauge bare wire thermocouple may be used successfully for detn. of avg. skin temp. of the quiet subject under limited environmental conditions, where an avg. accuracy of [plus or minus] 0.4[degree]C is sufficient.
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