In thermal energy storage applications involving phase-change materials (PCMs), it is essential to monitor changes in temperature and material state across multiple positions within a tank. This allows for the detection of temperature gradients and phase-boundary movement during melting or solidification processes. To address this need, several custom optical sensors based on LEDs paired with photodiodes or phototransistors are developed and tested. These sensors operate as light barriers and were specifically designed to detect phase state in media such as paraffin and water. Their simple construction and high sensitivity make them ideal for scalable sensor arrays in embedded applications. However, integrating a large number of analog sensors into a compact and costefficient system presents challenges, particularly because of the limited number of analog input pins on standard microcontroller peripherals. Therefore, this thesis presents the design and implementation of a switching circuit capable of acquiring signals from up to 64 analog sensors using a single analog-to-digital converter (ADC). The system architecture is based on analog multiplexers and binary decoders, controlled by a microcontroller that handles channel selection and data management. The circuit is modeled, simulated, prototyped on a breadboard and ultimately implemented on a custom-designed printed circuit board (PCB) to ensure signal integrity and minimize parasitic interference. The resulting system provides a reliable and modular platform for multi-sensor data acquisition in embedded PCM monitoring setups.
Development and Evaluation of a Measurement System for a Multi-Sensor Setup
Mehmedovski, E. (Author). 2025
Student thesis: Master's Thesis