A Lightweight IoT and Blockchain-Based Cold Chain Track-and-Trace Prototype for Medical Materials in Resource-Constrained Environments

Transporting and storing temperature-sensitive medical materials requires strict adherence to controlled conditions across multi-actor cold chains to ensure safety and efficacy. This challenge is amplified in resource-constrained environments, where cost-effective and verifiable monitoring solutions are limited. This study presents the design and implementation of a low-cost cold chain track-and-trace system integrating IoT sensors, edge computing, and blockchain technology. Temperature and GPS data are captured via sensors connected to a Raspberry Pi Pico microcontroller, published over Wi-Fi to an MQTT broker, persisted to database and relayed via an API to a Node.js server for persistence on the Polygon blockchain. A web application enables stakeholders to initiate shipment, and track shipment conditions and custody. Evaluation results show average round trip (sensor - MQTT broker - Node.js - blockchain - transaction confirmation) transaction write times of 10 seconds on Ethereum Sepolia, 10.5 seconds on Polygon Amoy, and 0.08 seconds on Ganache. Average transaction fees are approximately 0.05 ETH (Sepolia) and 0.05 POL (Amoy), demonstrating feasibility with cost and latency trade-offs.