Computational method for estimating the emissivity of human skin under different conditions: dry skin, sweaty and with lotion

Resumo

With the emergence of the Covid-19 pandemic, sanitary barriers that use infrared thermography have
become more relevant as a means of combating the spread of this type of disease, as it is a non-contact diagnosis
method. A crucial factor when working with thermography is the emissivity of the analyzed surface, a base
parameter that thermal imagers use to estimate the temperature. For human skin, researchers generally adopt the
emissivity value of 0.98. However, this value considers only the condition of dry skin in its natural state. Therefore,
it is necessary to estimate the emissivity of the skin in other conditions, such as sweating skin, which are common
in passersby of sanitary barriers. In this paper, the authors present an experimental procedure to obtain the forehead
emissivity of volunteers by using the electric tape method and a developed a computer program algorithm based
on Planck's Law of Thermal Radiation to enhance this method. Both approaches, the electrical tape method with
and without the developed algorithm, were applied to thermographic images of thirty-six volunteers. Both methods
obtained similar results, showing that it is possible to use the developed algorithm with the electrical tape method,
enabling emissivity estimates to be more efficient.