D. Ravindran and N. A. Jumadi, “Development of IoT-Based Heart Rate and Oxygen Saturation Alert System for COVID-19 Wards”, EEEE, vol. 3, no. 2, pp. 211–222, Nov. 2022, Accessed: Jul. 18, 2024. [Online]. Available: https://penerbit.uthm.edu.my/periodicals/index.php/eeee/article/view/8595