Turbidity monitoring of lake water by transmittance measuresment with a simple optical setup

We are developing a wireless sensor network system for the lake water quality monitoring, which consists of sensor module, wireless transceiver module, control IC's and power module. In the sensor module, sensors to monitor the water quality such as pH sensor, turbidity sensor, chlorophyll concentration sensor and dissolved oxygen concentration sensor, will be integrated as a microfluidic device. The power module of a sensor node of the wireless sensor network system will be implemented with solar cells and thermoelectric effect based energy harvesting devices utilizing temperature difference between the surface and the bottom water layer. In this paper, we report the feasibility study results of a turbidity sensor that will be integrated into the sensor module for the lake water quality monitoring. Our turbidity sensor has been achieved by a simple optical setup, which consists of LED and photodiode. The turbidity is determined by measuring the transmittance of scattered LED light by the particles in the water sample. As a result of experiments with the lake water sample, we could verify that our simple optical measurement setup can be a useful tool in turbidity sensing.