Once the project idea was finalised, the team began looking for cheap, energy and cost efficient, and standardised methods for growing plants. The hope was that a piece of affordable laboratory equipment could be sourced, or purchased, that would also be a suitable closed system for the growth of plants with our adaptor microorganisms. It was soon established that such an item did not exist to meet our specifications. Therefore, to address this lack of suitable hardware, we decided to design our own hydroponics system to allow us to grow large numbers of plant seedlings in a controlled environment for the purposes of our project.
Before building the system, the team worked together to establish the desired design parameters for the hardware:
1. The system needed to be cheap and easy to build from scratch. Enabling us to prototype the system and make it an attractive solution for future iGEM teams to develop and build on our design.
2. The system had to be versatile, open-source, and easily adapted to enable various experimental conditions to be tested for their effects on plant growth: a. Light intensity; b. Light wavelength; c. Day/night cycle.
By adopting such an adaptable design and making use of cheap off-the-shelf components, the intention is that the hardware platform is adaptable to the end user’s needs, with a simple open-source code interface to programme key experimental variables.
Several weeks were spent modifying the design until a design was found that met all the above criteria, the specifications of the design can be seen below.
SEEDLINGS CAN BE GROWN
KWH OF POWER ANNUALLY
USED TO POWER SYSTEM
PROVIDES UP TO
LUX OF LIGHT
TO GROW SEEDLINGS
Having identified the design parameters for the system, the next stage was to begin ordering parts and putting it together. The system was divided into three independent, functional sub-systems to make the task of assembling the system more manageable and allowing team members to focus on the sub-system that most suited their specialty. These three sub-systems were hardware, software, and the wetware interface.
The function of the hardware is to contain the electronics and organisms, power the LEDs/microcontroller and maximise the light available to the plants. Containment is through the use of a sealed box, with a detachable lid for access. This box is lined with tin foil and sprayed black to minimise the entrance of light from the external environment. Powering the LEDs proved to be more challenging and took our engineers a number of iterations to perfect. You can find further details on this process here. The final design is powered from a 5V 2.1A AC adapter that plugs straight in to a mains power supply. Alternatively, 4 AA batteries can be used to power the system for short periods of time if necessary. The LEDs are wired in parallel so the same light is provided along the length of the container. This can be seen from images in the Gallery.
The purpose of the software is to control the LEDs, by allowing the user to easily adapt features such as light intensity, wavelength and also specify the length of the day/night cycle. For our design, we use the Arduino UNO microcontroller to control these characteristics as it offers a user-friendly interface and is well-suited to our design. You can find all the code and a guide to the Arduino here.
The engineers, hard at work trying to troubleshoot issues with the system.
The finished product, set to a rainbow function that cycles through various wavelengths of light
Attributions: Umar Farooq, Luke Waller