Performance evaluation of LED Based sensor for water turbidity measurement

This paper evaluates the sensing performance of photodetector in response to different colours of light sources used for water turbidity measurement. Initially the best photodetector is chosen based on the voltage variation during ON/OFF condition. Once the photodetector is selected, a complete system is developed by implementing LABVIEW as a processing tool. Five samples of water with different turbidity were prepared and tested using different colours of LEDs. With respect to the actual values of the sample, the performances of the sensing system were evaluated. In terms of accuracy, White LED gives the best performance with less than 10% difference in most measurement and followed by UV LED. Meanwhile for precision, UV has the best performance as most of the measurement gives standard deviation of less than 1 and followed by White LED. Therefore the use of both colours are found to be suitable for water turbidity measurement ranging from 0 to 1000 NTU.