KNUST Research Week and Scientific Conference: Empowering Researchers to Achieve Impactful Outcomes

Accurate liquid level sensing is very essential in applications such as pharmaceutical, water, chemical and oil storage, where even minor errors can result in overflow, leakage, or pump failures that may result in explosions, environmental contamination, and costly downtime. However, current sensing methods still suffer from limited accuracy under dynamic conditions, sensitivity to environmental factors, and restricted applicability to liquid types and container geometries, highlighting the demand for more robust, versatile, and cost-effective solutions. This project introduced the development of a laser-based, non-contact, and continuous liquid level sensing system using the time-of-flight principle. A photodetector and a 940nm laser diode are integrated into a single unit and mounted at the top of the liquid container. The time taken by the emitted laser pulse to travel from the sensor unit to the liquid surface and get reflected to the detector (time of flight) is used to calculate for the liquid level in the container. The developed laser sensor device was tested with cooking oil and clean water over a 1cm to 25cm range to evaluate its accuracy and performance with liquids of differing refractive indices and surface properties. A mean percentage error of 0.58% and 3.83% were obtained for both the cooking oil and the clean water, respectively. The results indicate the system's accuracy for liquid level measurement, demonstrating higher accuracy for liquids of relatively higher refractive index. This approach to liquid level measurement is suitable for applications where the purity of liquids is a high priority, as it provides precise readings without needing to get in direct contact with the liquid regardless of the container geometry.