Team Members

The proposed plant monitoring network uses a distributed network of sensor nodes to monitor the environmental conditions of plants. By monitoring key environmental variables over time, such as soil moisture, soil temperature, ambient temperature, and sunlight, the growing conditions of most plants can be assessed. This permits for smarter caretaking of plants, allowing a greater number of plants to be cared for with less human labor, or even no human labor at all when integrated with other smart automation systems. By increasing the number of plants, this added vegetation can both absorb air pollutants and muffle the loud sounds of city life, thus improving the quality of life in large cities.

The proposed plant monitoring network is comprised solely of sensor nodes. What makes this sensor network innovative over other similar systems is that each sensor node is equipped to communicate via Wi-Fi (IEEE 802.11 b/g/n) and Bluetooth Low Energy [BLE]. This allows for all nodes to dynamically adapt to any system installation. When the node has direct access to a known Wi-Fi network, it will transmit data directly to a server over the Wi-Fi connection. These nodes can then act as connection points for other nodes which do not have direct access to form a mesh network, preferring BLE over Wi-Fi to save power. Since Wi-Fi and BLE use the same 2.4GHz frequency band, many wireless modules exist that can be used for both protocols. Arbitration of how nodes interconnect in the mesh network will be automatic and require no setup at the time of installation. Additionally, the network will be capable of healing itself when a node reaches the end of its battery life.

Each sensor node is comprised of two PCBs. The main PCB bears a microcontroller, a wireless module, and sensors to assess ambient temperature and light levels. The second PCB features another temperature sensor for measuring soil temperature and a capacitive probe to be inserted into the ground to measure soil-moisture. This second PCB also has castellated edges, allowing it to be directly attached to the first PCB. Once fully assembled, the PCBs are coated in a clear, protective layer to ruggedize the sensor node. This allows for the sensor node to be used without a protective housing, thereby reducing costs.

By using existing PCB manufacturing techniques, the sensor node can be produced in a cost-effective manner. Also, using techniques developed by the online community known as #badgelife, the sensor nodes can be designed to have attractive form factors in the shapes of plants such that they complement their surrounding environments. These techniques do not require any additional manufacturing technology or techniques to accomplish, but simply take advantage of manufacturing capabilities already present in industry. One example of how such a PCB could look is seen in the early prototype sensor node pictured with this entry.

Once the data from all the sensor nodes is collected at the server, the data can be analyzed over time to minimize water usage in the plant system and to ensure healthy living conditions for all monitored plants. If the system is integrated into a smart irrigation system, the plants can be autonomously watered by request from the server. If the system relies on human labor for plant caretaking, a summary of which plants need watering can be included in a list of tasks for the caretaker, reducing labor costs and overall water consumption. These savings allow for a greater number of plants to be cared for at the same or reduced cost.

Inspiration

When I saw that the challenge was about smart devices for cleaner water and healthier cities through IoT, I knew that I wanted to participate. I had recently completed a class project where I created the prototype version of this sensor node, but I wanted to improve and optimize the design further from the design requirements for the course project to different design requirements that I personally would want. Specifically, I wanted to upgrade from BLE to a WiFi/BLE hybrid model using the ESP32, allowing for a low-cost yet flexible solution. Finally, I appreciate the chance to compete with my fellow students around the globe for the grand prize.

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