The design is inspired by water buoys which are usually found in sea which are commonly used as indicators for boats and ships which are out in the open water. Buoys can be anchored and tethered to the ocean floor or be allowed to drift freely. This is beneficial in designing a sensor device to monitor a major waterway area as stationary buoys are capable of measuring water quality parameters in a desired monitoring site and drifting buoys are capable of collecting data from a large area of the waterway. This way, minimum number of buoys are needed to be able to effectively collect data of water quality for the waterway. The design is particularly innovative as currently, there are no sensors which are allowed to drift freely. Another challenge within wireless sensor data transmission also involves the range which the MCU is capable of transmitting the data as well as the need to maintain a constant power source without the hassle to change the batteries in the sensory unit.
The key components of the sensor buoy contain a transmission antenna, 3 solar panels as well as several sensor modules to monitor key parameters in water quality. The purpose of the 3 solar panels is to deliver renewable energy to continue powering the microcontroller unit within the buoy which will be responsible of temporarily storing and packaging raw sensor data. The solar panels will be particularly convenient as the solar panels will omit the need to change the batteries within the sensor buoy which are needed to power up the MCU and to transmit data to a local monitoring station. Solar panels are preferred over alternate sources of free energy as it is more efficient and reliable. For data transmission, RF is preferred over other forms of wireless data transmission. RF is preferred as it is capable of sending data over a longer range and with lower power consumption. One downside to RF data transmission is the low bit rate of data transmission, however the low bit rate will not be a significant hindrance for the sensor buoy as the volume of data transmitted is small. Another core component of the sensor buoy is the use of Arduino as it’s MCU. Arduino is preferred over other microcontrollers as it is inexpensive and easier to set up. Arduino MCUs (take Arduino Nano for example) are also much smaller as compared to other MCU which frees up more space within the sensor buoy. Finally, the sensors which will be used in the sensor buoy to measure the water quality parameters are sensors such as the DS18b20 temperature sensor, PHS-25 pH sensor, SAL-BTA salinity sensors to the sensor buoy. All the sensors are inexpensive and are normally used in IoT projects.
The sensor buoy will take 1 reading every 24 hours and will transmit the data to the local monitoring station. The reason for the low rate of which the waterway is monitored and sampled is to conserve the energy stored in the batteries of the sensor buoys. However, this issue will not be as significant as the multiple sensor buoys in the waterways can be configured to sample the water quality at different periods of the day which will provide a more consistent means to monitor the quality of the water in the waterway. Only one local monitoring station is needed for every single major waterway, which also includes an inexpensive Arduino MCU, a GSM transmitter, as well as a demodulator to receive the RF transmissions from the sensor buoys. As the channel used to send data to the local monitoring station is via RF, the sensor buoys need not be in proximity with the local monitoring station nor are multiple local monitoring station needed. The range of RF transmissions are about 8km which allows for this to happen. The local monitoring station will then send the data via cellular networks directly to the user’s mobile phone.
I believe that the sensor buoy is capable of making an impact in the world, especially in countries with poor water quality. The sensor buoy can be reproduced at a reasonable cost with minimal maintenance over the years. The sensor buoy also communicates with the local monitoring station without the need or reliance on major infrastructures such as cell tower or internet connectivity. This enables the sensor buoy to also be used in rural areas where none of the earlier mentioned infrastructures are mentioned. With the utilization of GSM, the readings taken by the sensor buoys can also be effectively presented to the user. This allows the user to monitor the water quality directly without needing non-portable devices such as computers. As the data is provided directly to the user, the user can also take actions on the waterway whenever drastic changes in water quality is detected by the sensor buoys.