HARDWARE

SENSOR SYSTEM

OVERVIEW

This year Lambert iGEM’s Sensor System is used to collect and display information from the current hydroponics system on the AgroSENSE mobile app. Information such as atmospheric CO2, water temperature, ambient temperature, humidity, pH, and light intensity is collected through a number of sensors placed in the system and then stored in an Arduino (micro-controller). This information transfers from the Arduino to the RaspberryPi, and from the RaspberryPi to an SQL cloud database, where the information is accessed through the mobile app. The system has automated responses based on anomalies in the pH, temperature, and others found in the sensor data.

DESIGN

Information on Electrical Sensors

Sensor Name	Purpose and Importance	Location in System	Measurement Intervals
DHT11	Temperature and Humidity	Outside the Hydroponics Frame	10 minutes
CO₂	Ideal carbon dioxide conditions for plants	Outside the hydroponics frame	10 minutes
pH Sensor	Maintaining ideal plant pH	Water reservoir	10 minutes
Water Temperature	Maintaining ideal water temperature for plants	Water reservoir	10 minutes
Light Intensity	Ideal light for plants	Inside hydroponics frame	10 minutes

Table 1. Chart of electrical sensors.

The CO₂, DHT11, and light intensity sensors are stored inside a box that hangs off of the central water pipe at the apex of the hydroponics system. The sensors send information to an Arduino Nano that is also held inside the sensor box. A cable runs from the Arduino, down the system, to a second sensor box at the base of the system by the sump tank. In this second box is the raspberry pi and a secondary Arduino that the pH probe feeds information to.

Figure 1. Enclosed environmental sensor box.

Figure 2. Open environmental sensor box with visible sensors and Arduino.

Figure 3. Closed secondary sensor box for the pH sensor and Raspberry Pi.

Figure 4. Open secondary sensor box with visible Arduino for the pH probe and Raspberry Pi.

Figure 5. Schematic for electronic sensors in the system.

AUTOMATED RESPONSE

As we continue to develop our project, our next goal is to develop an automated response network. If any of the conditions of the hydroponics system (water temperature, water ph, atmospheric temperature, and humidity) and eventually the g system exceeds optimal bounds for plant growth, the electronic sensor system will have an automated response that will actively maintain equilibrium conditions. This will be done using additional mechanisms controlled via a Raspberry Pi. Before data is sent to the SQL cloud database, it will be briefly analyzed by the Raspberry Pi itself to scan for any sub-optimal conditions. If for any reason it measures a value outside of the desired range for over 30 minutes (data collected in intervals of 10 min), the Raspberry Pi will send instructions to the Arduino to correct the anomaly, returning conditions to optimal levels. Solution temperatures will be maintained using a water heater while atmospheric temperatures will be controlled using a fan. Conditions such as pH and nutrient levels will be adjusted through buffer solutions, which will be fed into our system through an array of pumps coming from the reservoir.

HYDROPONICS SYSTEM

OVERVIEW

A hydroponics system is required to properly test the efficacy of nutrient production and to test the biosensors and mechanical sensors. The system is composed of a 25-gallon reservoir tank in a vertical hydroponics setup. Other components, such as a swirl filter and fish tank, are unnecessary for a hydroponics system, but they are essential to a successful aquaponics setup. We have designed the next hardware additions and will implement them for next year’s project.

DESIGN - SWIRL FILTER

OVERVIEW

A swirl filter is necessary to separate water and fish liquid waste from the fish feces. That way, solid matter does not circulate through the system and potentially harm the plants,fish or contaminate the produce. Furthermore, the solids will not interfere with the mechanical sensors built in the system.

PARTS

1 5-gallon bucket
1 ¾ inch inner diameter, 5 ft. long PVC tube
2 ¾ inner diameter PVC elbow connectors
3 ft. of ¾ inch inner diameter flexible vinyl tube
1 ¾ inch inner diameter valve
Plumbers epoxy

PROCEDURE FOR ASSEMBLY

Drill a 1 inch diameter hole into 3 areas of the bucket: one at the top just below the rim, one at the bottom just above the base, and one in the middle. No 2 holes should be on the same side of the bucket.
Cut the ¾ inch diameter tube into 3 segments: one 6 inch segment & two 1 foot segments. Insert the two 1 foot segments into the top and bottom holes, making sure the tubes do not extend past the middle of the bucket, and insert the 6 inch segment into the middle hole, only allowing the tube to be 2 inches inside the bucket. Secure the tubes to the bucket using plumbers epoxy.
Attach the elbow connectors to the top and middle tubes on the side inside the bucket. The elbow connector attached to the top tube should be facing up, while the elbow connector attached to the middle tube should be facing to the side. Apply plumbers epoxy as needed.
Attach the valve to the bottom tube on the side outside of the bucket.
Attach the vinyl tube to the middle tube on the side outside of the bucket. If needed, submerge the end of the vinyl tubing in hot water in order to make the tube wider.

Figure 6. Side view of swirl filter.

Figure 7. Top view of swirl filter.

DESIGN - FISH TANK

OVERVIEW

The fish tank is where the nutrients and waste will be created. This is the part of the mechanism where circulated and purified water from the hydroponics system enters the fish tank and impure and nutrient-rich water is transported to the swirl filter.

PARTS

20 gallon fish tank
Fish (preferably koi or tilapia)
3 ft. of ¾ inch inner diameter flexible vinyl tube (2x)

PROCEDURE FOR ASSEMBLY

Disclaimer- This assembly is for the second year continuation and is NOT in any way associated with this year’s project. The biosensors are NOT in any way in contact with the fish.

Set up the fish tank directly next to the aquaponics system, keeping it 6 inches below the base of the system. The top of the fish tank should be 6 inches above the swirl filter.
From here, connect one tube to the base of the aquaponics system (which already has a hole in the base) and the other into the side of the swirl filter (a hole that has ¾ diameter should be drilled into the side of the swirl filter).

DESIGN - HYDROPONICS SYSTEM

FULL PARTS LIST

pH sensor
Environment Temperature
Carbon dioxide sensor
Humidity sensor
Water temperature
Light Intensity
(1 needed) Raspberry Pi
(2 needed) Arduino
Breadboard
Wires
32 GB - sd card
Resistor Kit
2 x 2 x 1 ½ Y connector (24x)
2 inch x 5 ft pvc pipe (2x)
½ inch x 5 ft pvc pipe (2x)
¾ inch 90 degree elbow (2x)
¾ inch (inner) 1 inch (outer) 10 fr. vinyl flexible tube
46 in T-slot framing rails (2x)
76 in T-slot framing rails (4x)
3ft T-slot framing rails (2x)
Tarp
15 gallon bucket
Black plastic grow tray w/ drain
LED Grow Lights (set of 6)

ASSEMBLY

Start off by laying a tarp on the area of placement to ensure that if any spills occur, the ground below or around the system will not be damaged.
Then assemble the T- slot metal frames. The 76 inch metal frames will provide the structural integrity for the four sides of the system. The 3ft and 46 inch metal frames will provide extra support for the whole frame. From here, place the black, plastic tray on the lower metal frame. (Figure 1 & 2)
Below the plastic tray, place the 15 gallon bucket. In the bucket, attach the U.V. light, which helps decrease the amount of algae growth.
Initiate the application of the T-pipe at the top of the system and attach the vertical pipes to the T-connectors on the T-pipe.
Put the seedlings into the directed holes and run the system.

Plant Samples

Plants	# of Plants	Mass (grams)	Average Mass of Plant
Basli	8	16	2.13
Cilantro	6	17	2.83
Kale	16	276	17.25
Lettuce	20	333	16.65

Table 2. Harvest yields from sample initial crops.

Hydroponic Samples

Date	General Hardness	Nitrate	Nitrite	Chlorine	Potassium Hard	pH	Water Sampled
5/23	0	0	0	0.8	3	6.4	Tap Water
5/23	32	250	10	0.8	6	6.4	New Nutrient MaxiGrow
5/29	16	250	1	0.8	6	6.4	Hydroponic Sample
5/31	16	250	1	0.8	0	<6.4	Hydroponic Sample
6/7	32	250	10	0.8	6	6.4	New Nutrient MaxiGrow
6/14	0	0	0	0	3	6.4	Hydroponic Sample
6/15	8	250	10	0	6	<6.4	New Nutrient MaxiGrow
6/16	16	250	10	0	6	6.4	Hydroponic Sample - Water level was low
6/16	16	100	10	0	0	6.4	Hydroponic Sample - After water added to bring to level
6/21	0	0	0	0	3	6.4	Hydroponic Sample
6/21	32	250	10	0.8	6	6.4	New Nutrient MaxiGrow
6/28	0	0	0	0	3	6.4	Hydroponic Sample
6/29	32	250	10	0.8	6	6.4	New Nutrient MaxiGrow
7/2	0	100	0	0	3	6.4	Hydroponic Sample
7/14	0	0	0	0	3	6.4	Hydroponic Sample
7/14	32	250	10	0.8	6	6.4	New Nutrient MaxiGrow
7/21	0	0	0	0	3	6.4	Hydroponic Sample
7/21	32	250	10	0.8	6	6.4	New Nutrient MaxiGrow
8/2	0	0	0	0	3	6.4	Hydroponic Sample

Table 3. Results of water quality testing with RunBo Aquarium Test Strips. The weekly trends seemed to indicate a complete depletion of Nitrate ions over the 7 day period.