Project

# Title Team Members TA Documents Sponsor
73 Circle of Life: Automated Desktop Aquaponics System
 Aishwarya Manoj
Anjali Aravindhan
Estela Medrano Gutierrez
 Manvi Jha photo1.jpg
proposal1.pdf
# Circle of Life: Automated Desktop Aquaponics System

# Team Members:
- Aishwarya Manoj (am133)
- Anjali Aravindhan (anjalia2)
- Estela Medrano (estelam2)

# Problem

Urban living and limited indoor space make it difficult for individuals to grow fresh produce sustainably. Aquaponic systems offer an efficient solution by combining fish cultivation and plant growth in a closed-loop ecosystem, but existing systems require frequent manual monitoring and maintenance. Current desktop-scale aquaponics kits often lack intelligent control features and are cost-prohibitive for individual users.

# Solution

This project proposes the design and construction of a small desktop smart aquaponics system integrating automated environmental and fluid control. The system consists of a compact fish tank and plant grow bed forming a closed-loop water circulation path. An electronically controlled pump circulates water between the tank and grow bed, while a motorized dispensing mechanism provides automated fish feeding. A programmable grow-light module delivers controlled lighting cycles for plant growth. Embedded sensors monitor key system conditions such as water flow, ph level and water temperature. A microcontroller schedules feeding and lighting and processes sensor data. Depending on budget and difficulty, we may add more or less capabilities.

# Solution Components

## Subsystem 1: Fish Feeder Subsystem

A simple automated fish feeder will be implemented using an SG90 servo motor (linked below) operating between two angular positions, one away from the fish tank and another towards the fish tank for dispensing food. A custom 32-printed food container will be mechanically coupled to the servo shaft using screws and will include a small outlet opening that allows food to dispense when the container is rotated downwards. The servo motor will be controlled via PWM signals generated by a microcontroller. This microcontroller will also serve as the controller for the other subsystems.

[https://www.digikey.com/short/0r42n3vv](url)

## Subsystem 2: Lighting Subsystem

The lighting subsystem serves as the artificial light sources for plants in our desktop aquaponics system. The purpose of this subsystem is to make sure plants will get the correct amount of light and intensity per day to simulate growth due to sunlight from the Sun. The lighting subsystem will use LED colored lights with alternating blue and red colors to simulate sunlight and promote photosynthesis. We plan on using the Royal Blue and Deep Red ASMW-LL00-NKM0E LEDs from DigiKey (also linked below this section) connected to a LED driver to both control the lighting system and step down the input voltage of the PCB to the 3.08V needed by the lights. This LED driver will be in the same PCB as the microcontroller system and will use the same microcontroller. It will be mounted above the plants and the aquarium portion of the aquaponics system and shine down upon the plants.

[https://www.digikey.com/short/zcmqv3wj](url)

## Subsystem 3: Water Quality Subsystem

This subsystem monitors water quality through various sensors and allows for us to ensure that the aquaponic system is working properly. The three main components of this subsystem are the water flow sensor (314150005 from DigiKey), the water PH sensor (SEN0161 from DigiKey), and the water temperature sensor (Waterproof 1-Wire DS18B20 Digital temperature sensor) As we have a water pump pushing water up through our aquaponic system and bringing water to the plants above the fish tank, we need to measure the flow rate of the water to ensure that this component is operating effectively. The water flow sensor will thus measure the flow of water and ensure that the water is pumping effectively up the system. Alongside this, we will have a PH sensor to measure the PH of the water, which is critical for the health of both the fish and the plants. As we aim to have beta fish in the tank, that requires a PH of roughly 6.8 to 7.5, and we will have plants that require that slightly acidic to neutral PH range as well. If the PH is outside of this range, we will have a LED indicator (sourced from our component kit) so that the user knows it is time to change the water. Finally, we will have a sensor measuring the temperature of the water to ensure that it is habitable for the fish. Again, for beta fish this requires a temperature of 76 to 85 degrees Fahrenheit. The temperature sensor will measure the temperature of the water in the tank and if it is too high or too low, an LED indicator will be triggered, allowing the user to change the water or the temperature of their room.

[https://www.digikey.com/short/r7f95h7j](url)

[https://www.adafruit.com/product/381?srsltid=AfmBOop4JLBfv5qedUGq36frDQX9vyVTusMKieUlSaGwtCNAFJlJTlm4](url)

[https://www.digikey.com/short/v9btn5d9](url)

## Subsystem 4: Power Subsystem

The power subsystem’s main goal is to provide power to the other subsystems in this project, including but not limited to the lighting, fish feeder, water quality, and pump. To start the project will need an AC to DC 12V converter that is linked below. The voltages of the components will be the following:
- The microcontroller unit, either a STM32- or a ESP32-class IC, requires 3.3 volts. For example, a STM32G4/F4 or a ESP32-S3.
- The LEDs require a voltage of 3.08V and 200mA.
- The water flow rate sensor requires an input voltage of at least 5V.
- The PH sensor also requires an input voltage of 5V. The water temperature sensor’s power is between 3.0V to 5.5V.
- The circulation pump ranges from 6V to 18V.
- The water feeder servo uses 5V.
Thus, we will be using a voltage regulator to step down the voltage from 12V to 5V for all of the systems, and a LDO to step it down to 3V for the LEDs.

[https://www.digikey.com/short/dbfnfn48](url)

[https://www.digikey.com/short/bf0mqfjh](url)

[https://www.amazon.com/12V-Power-Supply-Adapter-Transformer/dp/B07DMFN2YN](url)

## Subsystem 5: Water Pump Subsystem

The water pump will be in series with the water flow sensor, sending the water from the fish tank up to the plants. We will be using a FIT0563 circulation pump that is waterproof, and depending on the water flow sensor’s outputs, we will be controlling the speed of the circulation pump by PWM modulating the supply voltage using a MOSFET.

[https://www.digikey.com/short/cr79t182](url)

# Criterion For Success

- The pH sensor accurately measures the pH
- The temperature accurately measures the temperature of the water
- The flow rate sensor accurately measures the flow rate
- Water is able to flow in a circular loop from the aquarium to the plants and vice versa
- Automated fish feeder is able to supply food into the fish tank once every 24 hours
- Lighting is able to mounted above the plants and has daily lighting schedule that changes based on the time of day (24 hour schedule implemented)
- The LED indicators accurately indicate temperature that is too cold or warm, and water that has a PH too high or low (unsafe for fish)

Healthy Chair

Ryan Chen, Alan Tokarsky, Tod Wang

Healthy Chair

Featured Project

Team Members:

- Wang Qiuyu (qiuyuw2)

- Ryan Chen (ryanc6)

- Alan Torkarsky(alanmt2)

## Problem

The majority of the population sits for most of the day, whether it’s students doing homework or

employees working at a desk. In particular, during the Covid era where many people are either

working at home or quarantining for long periods of time, they tend to work out less and sit

longer, making it more likely for people to result in obesity, hemorrhoids, and even heart

diseases. In addition, sitting too long is detrimental to one’s bottom and urinary tract, and can

result in urinary urgency, and poor sitting posture can lead to reduced blood circulation, joint

and muscle pain, and other health-related issues.

## Solution

Our team is proposing a project to develop a healthy chair that aims at addressing the problems

mentioned above by reminding people if they have been sitting for too long, using a fan to cool

off the chair, and making people aware of their unhealthy leaning posture.

1. It uses thin film pressure sensors under the chair’s seat to detect the presence of a user,

and pressure sensors on the chair’s back to detect the leaning posture of the user.

2. It uses a temperature sensor under the chair’s seat, and if the seat’s temperature goes

beyond a set temperature threshold, a fan below will be turned on by the microcontroller.

3. It utilizes an LCD display with programmable user interface. The user is able to input the

duration of time the chair will alert the user.

4. It uses a voice module to remind the user if he or she has been sitting for too long. The

sitting time is inputted by the user and tracked by the microcontroller.

5. Utilize only a voice chip instead of the existing speech module to construct our own

voice module.

6. The "smart" chair is able to analyze the situation that the chair surface temperature

exceeds a certain temperature within 24 hours and warns the user about it.

## Solution Components

## Signal Acquisition Subsystem

The signal acquisition subsystem is composed of multiple pressure sensors and a temperature

sensor. This subsystem provides all the input signals (pressure exerted on the bottom and the

back of the chair, as well as the chair’s temperature) that go into the microcontroller. We will be

using RP-C18.3-ST thin film pressure sensors and MLX90614-DCC non-contact IR temperature

sensor.

## Microcontroller Subsystem

In order to achieve seamless data transfer and have enough IO for all the sensors we will use

two ATMEGA88A-PU microcontrollers. One microcontroller is used to take the inputs and

serves as the master, and the second one controls the outputs and acts as the slave. We will

use I2C communication to let the two microcontrollers talk to each other. The microcontrollers

will also be programmed with the ch340g usb to ttl converter. They will be programmed outside

the board and placed into it to avoid over cluttering the PCB with extra circuits.

The microcontroller will be in charge of processing the data that it receives from all input

sensors: pressure and temperature. Once it determines that there is a person sitting on it we

can use the internal clock to begin tracking how long they have been sitting. The clock will also

be used to determine if the person has stood up for a break. The microcontroller will also use

the readings from the temperature sensor to determine if the chair has been overheating to turn

on the fans if necessary. A speaker will tell the user to get up and stretch for a while when they

have been sitting for too long. We will use the speech module to create speech through the

speaker to inform the user of their lengthy sitting duration.

The microcontroller will also be able to relay data about the posture to the led screen for the

user. When it’s detected that the user is leaning against the chair improperly for too long from

the thin film pressure sensors on the chair back, we will flash the corresponding LEDs to notify

the user of their unhealthy sitting posture.

## Implementation Subsystem

The implementation subsystem can be further broken down into three modules: the fan module,

the speech module, and the LCD module. This subsystem includes all the outputs controlled by

the microcontroller. We will be using a MF40100V2-1000U-A99 fan for the fan module,

ISD4002-240PY voice record chip for the speech module, and Adafruit 1.54" 240x240 Wide

Angle TFT LCD Display with MicroSD - ST7789 LCD display for the OLED.

## Power Subsystem

The power subsystem converts 120V AC voltage to a lower DC voltage. Since most of the input

and output sensors, as well as the ATMEGA88A-PU microcontroller operate under a DC voltage

of around or less than 5V, we will be implementing the power subsystem that can switch

between a battery and normal power from the wall.

## Criteria for Success

-The thin film pressure sensors on the bottom of the chair are able to detect the pressure of a

human sitting on the chair

-The temperature sensor is able to detect an increase in temperature and turns the fan as

temperature goes beyond our set threshold temperature. After the temperature decreases

below the threshold, the fan is able to be turned off by the microcontroller

-The thin film pressure sensors on the back of the chair are able to detect unhealthy sitting

posture

-The outputs of the implementation subsystem including the speech, fan, and LCD modules are

able to function as described above and inform the user correctly

## Envision of Final Demo

Our final demo of the healthy chair project is an office chair with grids. The office chair’s back

holds several other pressure sensors to detect the person’s leaning posture. The pressure and

temperature sensors are located under the office chair. After receiving input time from the user,

the healthy chair is able to warn the user if he has been sitting for too long by alerting him from

the speech module. The fan below the chair’s seat is able to turn on after the chair seat’s

temperature goes beyond a set threshold temperature. The LCD displays which sensors are

activated and it also receives the user’s time input.

Project Videos