Hardware

Stage One

Design

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, to enable us to prototype the system and to 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 wavelengths. 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.

UP TO

1344

SEEDS CAN BE GROWN

IN HYDROPONICS

APPROXIMATELY

70

KWH OF POWER ANNUALLY

USED TO POWER SYSTEM

PROVIDES UP TO

1700

LUX OF LIGHT

TO GROW SEEDS

CONTAINS

120

INDIVIDUALLY ADDRESSABLE

LOW-POWER LED'S

Stage Two

Assemble

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 biological aspects.

The function of the hardware is to contain the electronics and organisms, power the LED’s/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 glued with tin foil and sprayed black to minimise exchange of light with the environment. Powering the LED’s proved to be more difficult, taking our engineers many days to find the optimal solution. You can find all the grizzly details on this process here. However, essentially the system is powered from a 5V 2.1A AC adapter that plugs straight in to your mains power supply. Alternatively, you can use 4 AA batteries to power the system for short periods of time if necessary. The LED’s 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 LED’s, 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 laid bare 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

Stage Three

Test

Substantial time was spent carrying out extensive research, both inside and outside the lab, in order to optimise the system for the target audience. This included speaking with organisations and individuals in industry who are involved with hydroponics-based systems or those who may be interested in working with such a system in the future. Some of the individuals we liaised with include Chris Tapsell, the Research Director of KWS UK, one of the biggest seed companies in the world, and Richard Ballard, co-founder of Growing Underground in London where they hydroponically grow micro greens and salad leaves 33 metres below the ground. These potential clients helped us focus our product so that it can better meet the needs of our clients.

In addition to gathering external opinion on our system, we also did our own tests on system performance. This included tests to verify the optimal light intensity, wavelength and positioning. The graph below illustrates how the light intensity (measured in lux) varies over time (in seconds) when the system is operated under various wavelengths of light. The black line indicates the system running with the rainbow function loaded which cyclically varies the light wavelength. As the results showed that blue, red and purple light and provided the most lux we are currently using these in the system but plan to use the rainbow function too in future to see how this affects growth or the aesthetics of the plant.