Design and Implementation of a Distributed Temperature Monitoring System for Cold Chain Logistics in Kaduna State

Cold chain integrity is critical for pharmaceutical and food product distribution in Kaduna State, North West Nigeria, where temperature excursions during transportation frequently compromise product quality and patient safety. This project designed and implemented a distributed temperature monitoring system for cold chain logistics vehicles operating between Kaduna and Kano. A DS18B20 digital temperature sensor array was installed at three monitoring points within each refrigerated truck compartment, connected to an ESP32 microcontroller with GSM capability. Temperature readings were logged locally at one-minute intervals and transmitted to an AWS IoT Core platform via MQTT over 4G connection when cellular coverage was available, with local SD card buffering when offline. A web dashboard displayed live temperature readings, historical graphs, and automatic email alerts when temperature exceeded the cold chain threshold of 2 to 8 degrees Celsius for pharmaceuticals. The system was deployed on two refrigerated trucks operating the Kaduna to Kano pharmaceutical distribution route over 21 days. Temperature breach events were correctly detected and alerted in 100 percent of cases, with alert latency below 90 seconds. Four previously unrecorded temperature excursion events were captured compared to the paper-based log that recorded zero events for the same period. Data synchronisation on return to 4G coverage showed zero data loss across all offline buffering periods. Total cost per truck installation was 34,000 naira. The study recommends extending deployment to refrigerated pharmacies and integrating with the National Agency for Food and Drug Administration's pharmaceutical logistics monitoring initiative.