Evaluation and correction of infrared temperature readings inside a neonatal incubator with the MLX90614 sensor using a temperature controlled black-body emulating a neonatal head

A method to assess the exactitude of the MLX90614 infrared temperature sensor inside closed neonatal incubators has been implemented. A temperature controlled PVC cylinder acting as a radiating black-body with the size of a typical neonatal head perimeter and volume filled with stirring water has been designed and built. The cylinder has been placed with its axis over the incubator mattress and the infrared sensor placed at 5cm above. Two 20 hour and one 35 hour experiments were performed to sweep two different temperature ranges to obtain the relationship between measured infrared temperature, real object temperature and incubator air temperature. Two equations to correct the infrared temperature reading were found, each for an experiment and temperature range. For the range of 29.5 °C to 40.5 °C the corrected temperature error spanned -0.6°C a +0.8 °C while for the 35.5 °C to 38.5 °C the error was -0.4°C a +0.4 °C. The main source of error was the incubator air temperature oscillation and ambient light entering the incubator. Error could be reduced considering the measured light intensity signal.