Team:Cambridge-JIC/Technology

Marchantia Growth Facility

Problem Statement

Growth chambers for the cultivation of plants are widely commercially available in a variety of configurations, from the simple cold frame to advanced climate control devices. They are, however, generally unsuitable for growing small lower plants such as marchantia in a synthetic biology setting. The reason for this is two-fold; firstly, commercially produced growth chambers are usually designed to grow higher plants such as wheat and are typically very large pieces of equipment. Furthermore, growth chambers with the ability to perform active climate control are costly and have a much greater feature set than is required for the controlled cultivation of marchantia. Secondly, current low-cost solutions for plant growth devices are generally of the greenhouse type, and are thus incapable of maintaining any active climate control.

In light of this, the problem statement for the Marchantia Growth Facility (MGF) was given as follows;

The task is to create a low cost device capable of cultivating marchantia by controlling the light conditions and air flow to the plants. In addition, the device must act to prevent the growth of foreign organisms on the marchantia plates, which could contaminate the specimens and hamper plant growth.

Hardware

As shown in figure [LINK TO FIGURE] , the MGF consists of a cuboidal chamber, which is divided into four subchambers. Each of the subchambers has an identical fan and lighting unit, all of which are controlled with an arduino microcontroller.

Software

As the MGF has no manual controls, it is controlled entirely from the software uploaded to the arduino

Manufacture

The hardware for the MGF was designed in VCarve Pro to be cut out of 9mm MDF and 3mm acrylic using a CNC router. This file [LINK TO FILE] contains all of the design files in VCarve and dxf formats. The design assumes the use of a 3mm cutter, normally positioned to follow the outside of rectangular vectors, and the inside of circular vectors. The exception to this is the pocket sections of the lid, which should be cut to a depth of 5mm inside the pocket vector..

Assembly Instructions

Materials required; one complete set of MDF parts, one complete set of acrylic parts, one arduino microcontroller, one project box approx 100mm cubed, four 40mm square 10mm thick 5V DC fan units, twenty Adafruit flora Neopixels, one stripboard, two 5V 1A regulators with heatsinks, one 9V power supply, one reel of equipment wire, one box of panel pins, one bottle of wood glue, one bottle of acrylic cement, spray paint (optional).

Mechanical Assembly

Begin by assembling the outer walls of the chamber onto the chamber base. First, drill holes of the same diameter as your panel pins, pitched at around 50mm around three sides of the base and on the back edge of the two side panels. Then assemble the joint using glue on the mating faces and secure by knocking a pin into each pre-drilled hole. Clamp and wait around four hours until the glue has cured.

Now assemble the inner walls of the chamber as a sandwich with the outer walls. It is important to check the inner walls for a good fit before gluing, as some small adjustments may be necessary. If the interior panels are found to be slightly oversize, they can be reduced to fit using a belt sander. Once glue has been applied, clamp the joint until the glue has cured. This will take longer than the first joints due to the large area being glued, so wait around six hours for the glue to cure.

The assembly can now be painted, and the dividers installed. Depending on the tolerances of the MDF parts, the dividers may require some force to be installed, which can be applied with a wooden mallet without danger to the acrylic. Then rotate the assembly so that the front is facing upwards and glue the front panel onto the dividers, such that it is flush with the top of the dividers using acrylic cement. Once the cement cures, seal the edges of the front panel with a bead of silicone sealer.

Electronic Assembly

Begin by fixing five NeoPixels to the base of each light unit (the panel with the hole in) in a ring around the central hole using epoxy resin, making sure the arrows on the data pads of the NeoPixels follow each other in a ring. Once the resin has cured, connect all of the positive terminals together using short lengths of equipment wire. It will help to tin the ends of the equipment wire and put a blob of solder on each pad prior to making each connection. When the positive terminals are connected, connect the ground terminals in the same manner (It is extremely helpful to use different colours of wire for the different terminals, as it allows you to quickly identify the wires after they have been routed to the control box). The data terminals can then be connected in a similar manner, but they should not be connected in a full ring; i.e. one of the links in the rink should be broken, so that there is a start and an end to the chain of pixels. Then solder half a metre of wire to the positive, ground and data terminals of the start pixel and pull all three wires through the central hole.

Mini Growth Facility

Problem Statement

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The problem statement for the mini growth facility was therefore given as follows;

The task is to construct a .