A Low-Cost IoT-Based Temperature and Humidity Monitoring System Using DHT11 and Bluetooth Communication with Mobile Integration

This paper presents the design and implementation of a low-cost, portable temperature and humidity monitoring system based on the Arduino Uno microcontroller, a DHT11 sensor, and Bluetooth-enabled mobile integration using MIT App Inventor. The system enables real-time environmental monitoring by transmitting sensor data wirelessly to a smartphone. A structured methodology was followed, including hardware configuration, embedded code development, and mobile application logic for Bluetooth communication and text-to-speech feedback. Debugging and iterative testing were carried out to ensure accurate sensor readings and seamless device pairing. Results confirmed reliable data acquisition, efficient Bluetooth transmission, and a responsive user interface. The system demonstrates significant potential for use in educational environments, smart home applications, and remote monitoring scenarios where affordability, simplicity, and portability are paramount. Future work includes cloud data logging, enhanced GUI features, and integration with additional sensor modules.