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.

Growing in Contained Environments

The use of biotechnology to modify plants has become common place in agricultural research - but we have conceptualised this as common place in agricultural practice. (See our human practices). In the context of our project, the purpose of containment is to prevent recombinant DNA from transgenic organisms being transferred to populations outside of our urban farm in Newcastle’s Victoria Tunnel (although the safety principals apply to any contained environments in which our transgenic organisms are present).

Genetically engineered organisms are subject to special rules intended to ensure that they are used in a way that does not pose an unacceptable risk to human health - or the environment. In order to design our hydroponic urban farm to meet these biosafety standards, we referred to:

• Greenhouse Research with Transgenic Plants and Microbes: A Practical Guide to Containment
• Reducing the Carbon footprint of crop production due to reduced food millage.
• No agricultural run-off.
• Limited need for pesticides and fertilisers.
• Safer crops as there is less risk of contamination.
• Reduced spoilage because of shorter transportation times and reduced handling.
• Less agricultural pollution.