The Plant Fitbit

In this project we explore how to create interactive products that will encourage stronger connections between people and nature. This product that we created is a smart plant monitoring system that uses sensors to track environmental conditions such as soil moisture, temperature, humidity, and light .

The device communicates plant health through a physical output, using a servo-driven leaf that will change position depending on moisture level. This creates an intuitive way for users to understand the needs of their plant, rather than relying on purely digital screen data.

List everything clearly:

1. 3 ESP8266
2. 1 Capacitive soil moisture sensor
3. 1 Photoresistor
4. 1 Temperature & humidity sensor (DHT11/DHT22)
5. 1 Servo motor
6. 1 Breadboard and 2 soldered board
7. a bunch of Wires
8. 3D printed housing

The aim of the Plant Fitbit is to be able to monitor your plant through your Fitbit as well as visually. There are two housing units in this product. The flower (housing 1) has a photoresistor, temperature/humidity sensor, and capacitive moisture sensor. The moisture sensor moves a servo motor which is connected to a leaf, indicating high and low moisture levels (pointing lower = low moisture, pointing higher = high moisture). The temperature/humidity sensor and photoresistor upload their data onto a shared MQTT server, which is then accessed by housing 2. Housing 2 (the Garden Marker) is an LCD display that shows the data uploaded to the shared MQTT server.

Design Rationale:

The flower-inspired 3D housing was chosen as it felt fitting for what we were trying to achieve. A biomimetic approach was used to make the interaction more intuitive and engaging. Different sensors required specific positioning to ensure accurate data collection. For example, the temperature, humidity and light sensors were placed higher up in the “pollen” area to get more accurate environmental readings. The leaf’s purpose is to give an immediate understanding of the plant’s health, rather than relying purely on an LCD screen. Separating the system into two housings allows the sensing unit to remain embedded within the plant, while the display unit can be positioned elsewhere for more convenient monitoring.

MQTT and Smart System explanation:

This system uses MQTT (Message Queuing Telemetry Transport) to send sensor data from the sensor housing to the display housing. This allows a wireless connection between the two. The sensor data collected (temperature, humidity, and light) is published to a shared server, where it is then received by the ESP8266 connected to the LCD display in the second housing. This could be further expanded to include mobile applications or multiple plant devices connected within the same system.

Circuit 1 (LCD display)

This circuit is used to display environmental data collected from the sensors using an LCD screen. The setup uses an I2C interface, which simplifies wiring by reducing the number of connections required between components. It is the only circuit that has its own separate housing.

Components used:

1. ESP8266
2. I2C
3. LCD (Liquid Crystal Display)

Why an I2C was used:

The I2C (Inter-Integrated Circuit) module allows the LCD to communicate with the ESP8266 using only two data pins, rather than multiple digital pins. This made the circuit more compact and easier to manage, especially during prototyping.

The LCD with I2C has four main pins:

1. GND -> GND (ESP8266)
2. VCC -> 3.3V
3. SDA -> D2
4. SCL -> D1

Circuit 2 (capacitive moisture sensor and servo)

This circuit focuses on creating a physical and intuitive way to display plant health using movement rather than a digital screen. Instead of sending data to the LCD, the system uses a servo motor to visually represent the moisture level of the soil. It is located at the bottom of the flower, as the capacitive moisture sensor needs to be inside the soil.

Components used:

1. ESP8266
2. Capacitive soil moisture sensor
3. Servo motor
4. Connections

Moisture Sensor:

1. VCC -> 3.3V
2. GND -> GND
3. OUT -> A0

Servo Motor:

1. VCC -> 5V / Vin
2. GND -> GND
3. OUT -> D4

Circuit 3 (temperature/humidity and light sensor)

This circuit focuses on collecting environmental data from the plant’s surroundings to later send to Circuit 1, specifically temperature, humidity, and light levels. These sensors are positioned at the top of the structure, within the “pollen” area of the flower, to ensure they receive accurate readings from the environment.

Components used:

1. ESP8266
2. DHT11 / DHT22 Temperature & Humidity Sensor
3. Photoresistor
4. Resistor
5. Connections

Temperature & Humidity Sensor (DHT11/DHT22):

1. VCC -> 3.3V
2. GND -> GND
3. OUT -> D3

Photoresistor:

1. VCC -> 3.3V
2. Pin -> A0
3. Resistor A0 -> GND

Limitations of this product

1. Only moisture currently controls the servo.
2. Sensors are not fully integrated.
3. Housing quality is quite poor.
4. Wiring reliability is an issue, as wires came loose frequently.

A key limitation of the current prototype is that the servo feedback is based solely on moisture levels, rather than a combination of environmental factors. Additionally, the physical housing lacks refinement due to challenges in the 3D printing process, and some wiring connections may not be durable long-term.

Future Improvements

1. Combine all sensor data to create a more accurate output.
2. App integration (we did not create wireframes or fully develop the Fitbit app concept).
3. Improved housing design.
4. Better soldering or use of a PCB.

If we were to continue this project, we would integrate all sensor data to create a more accurate representation of the plant’s health through the servo motor. We would still keep the LCD screen so users can better understand what the plant is lacking. The system could also be connected to a mobile application as well as a Fitbit, creating a platform to connect with other gardening enthusiasts while monitoring plants remotely. This could include notifications updating users on how their plant is doing. Additionally, refining the housing design and implementing a more robust circuit would improve durability and overall product quality.