Design and Evaluation of Cost-Effective Ultrasonic Sensors for Aggregate Temperature Measurement

The development and verification of Ultrasonic Oscillating Temperature Sensors (UOTS) for measuring aggregate air temperature in residential settings is the primary focus of this thesis. Conventional temperature sensors, while commonly used, have limitations, including time lag and localised measurement. In contrast, UOTS provides a more comprehensive solution by offering rapid, responsive temperature measurements across the entire ultrasonic pathway using cost-effective piezo transducers. The research involved designing and experimenting with an air based UOTS system, specifically built using standard 20x20 aluminum profiles and ultrasonic transducers. This system was driven by an integrated circuit, equipped with dual operational amplifiers, and connected to conventional sensors (AHT20 and BMP280) via an I2C interface to serve as a reference temperature logger. Experimental setups included using A cardboard thermal testing enclosure and a domestic hairdryer to isolate the assembly from room air movements and rapidly heat the air, allowing for detailed monitoring of temperature changes. Key findings revealed that the UOTS responded much faster to abrupt temperature changes than conventional sensors. The UOTS demonstrated reliability over prolonged periods and varying distances (0.15 to 0.95 meters), showing sensitivity in the order of ~50 Hz/K. However, the research also concluded that while UOTS is effective for detecting rapid temperature changes, conventional sensors remain necessary for continuous monitoring, especially in environments with varying air movements. Overall, this research highlights the potential of UOTS in residential temperature control applications, offering a low-cost, efficient alternative to traditional sensor networks. The study opens the door for further advancements in temperature measurement technology, particularly in the context of smart homes and energy-efficient climate control systems.