An ESP32-Based Multi-Sensor Architecture for Smart Environmental Monitoring: Design and Functional Evaluation

This paper presents the design and functional evaluation of an Internet of Things (IoT) environmental-monitoring architecture based on an ESP32 microcontroller and the ThingSpeak cloud platform. The architecture comprises six heterogeneous sensing subsystems: BME280 temperature, relative-humidity and barometric-pressure sensing; MQ-135 broad gas-response sensing; GP2Y1010AU0F optical dust sensing; TSL2561 illuminance sensing; YL-69 relative soil-moisture sensing; and an SPH0645LM4H I2S digital MEMS microphone. The engineering contribution is the development of a common sensing-to-cloud workflow spanning I2C, analogue-to-digital conversion and I2S acquisition, local processing, Wi-Fi connectivity and cloud visualisation. Experimental records demonstrate functional acquisition across the six sensing subsystems while also identifying calibration, data-provenance and hardware-integration limitations that must be addressed before reference-grade deployment.