Construction of a Contactless Infrared Thermometer Using MLX90614 Sensor for Fever Screening at Public Checkpoints

Background: The COVID-19 pandemic and recurring infectious disease outbreaks in Nigeria have underscored the need for rapid, contactless fever screening at public gatherings and checkpoints. Low-cost locally constructed devices can supplement scarce imported equipment. Aim: This project constructed and validated a contactless infrared thermometer using an MLX90614 sensor for fever screening deployment at public checkpoints in Nigeria. Methods: The MLX90614 infrared temperature sensor was interfaced with an Arduino Nano and a 0.96-inch OLED display. An audible alarm activated for readings above 37.5 degrees Celsius. Calibration was performed against a certified contact thermometer using a controlled blackbody source across a range of 35 to 42 degrees Celsius. Validation was conducted on 120 volunteers at a market checkpoint in Oyo State. Results: Mean absolute error relative to contact thermometry was 0.19 degrees Celsius. Fever detection sensitivity was 93.3% and specificity was 96.8%. Screening throughput was 15 to 20 persons per minute. Component cost was NGN 7,500. Conclusion: The constructed contactless thermometer is accurate, fast, and cost-effective for public fever screening. Waterproofing and ruggedisation of the enclosure are recommended for outdoor deployment. Keywords: contactless thermometer, infrared sensor, fever screening, COVID-19, Nigeria.