Applied Design

IMPACT Cartridge

The cartridge we designed is made to be very cheap to produce (just injection molded plastics and bacteria), and very easy to use. It does not require any extra expensive lab equipment nor would it need much training. This has clear advantages compared to more involved methods such as PCR analysis which need a well stocked lab with highly trained personnel.

Operation

The instructions are essentially printed on the cartridge itself, you simply turn the 3-way valve 45° for every step. The syringe is preloaded with a hydrogen peroxide solution (30%), and does not have to be loaded by the consumer.

• Step 1: Put a syringe with the sample you wish to measure in the top (between 10-40ml).
• Step 2: Turn the valve to Sample and empty the syringe.
• Step 3: Turn the valve to Close and pull out the empty syringe.
• Step 4: Now the bacteria will be re-hydrated and start to grow. In this step you put the cartridge as a whole into an incubator and monitor it. After a set amount of time you can look through the window to see if phages have been detected.
• Step 5: After you're done measuring you can dispose of the bacteria by putting the valve to Kill and squeezing the syringe.
• Step 6: The syringe should now be empty and the valve can be set to safe.

Cartridge Design

We started out with a 2D blueprint for a box with slides that could be opened from the outside by the operator. In this idea the bacteria would be a freeze dried powder in the reaction chamber. To get the bacteria to grow a growth medium would first be added before the milk sample, and the whole box would go inside a incubator. Afterwards the whole thing would be autoclaved or incinerated. It was decided that the slides idea would be too hard to make waterproof, plus any leakage would be to the outside.

We redesigned it to have as few components penetrating the cartridge as possible, to make it as safe as it can be. Furthermore we made it a lot safer already by putting the bacteria inside a semipermeable plastic, so even if anything leaked the bacteria would not be able to get out. This new plan was worked out in 3D and a prototype was printed using our extruder 3D printer. The problem with this design was immediately obvious as the fidelity of the racks and pinions (gears) was too low to work right. Plus we had doubts concerning the slides going sideways instead of smoothly to either side (the rollers would try to prevent this).

Making it watertight seemed daunting at this point. We had another insight that we did not need to add growth media separately, being L. Lactis they should already grow in a milk sample. To make them grow we would simply add freeze dried nutrients to the bacteria package, that way you would only need to add water (taken from the milk sample). A previous Groningen team (2012) has done something similar with a semipermeable package. We simplified the design by removing all the gears and went back to the sliders for a moment. In this new design we would not need a growth medium compartment but would add a compartment with a hydrogen peroxide solution instead. This solution would be added after the milk sample and the measurement was done to neutralize the bacteria and make it safe without needing an autoclave on hand. This idea we got from ARSOlux, we became aware of them and their project in our skype call with Wouter Ghering. It sort of worked after printing and assembling, but it was very hard to keep it watertight at the sliders, and it was not as user friendly as you want it to be. Clearly we needed something more reliable.

Finally we came up with using a simple IV three way valve. These are clearly build to a high standard, as well as extremely cheap. They have almost exactly the functionality of the earlier gear system, but then build into one part. Gluing it in required a special glue for polypropylene, but the whole thing works well. For demonstration purposes we added a small hole to let out the fluid in the reaction reservoir, and added a larger transparent back pane (clear PMMA). This was to be our final design.

Semipermeable Plastic

There are various semipermeable plastics. They work the same as semipermeable membranes in that they allow the passage of a certain size of particle. For our purposes we need a plastic with pores in it of around 100nm. That way they can let through the water and phage particles while retaining the bacteria. The most obvious plastics are Low density polyethylene or cellophane, both are in use as semipermeable plastics in other applications (dialysis membranes for example).

The rest of the casing would be made out of injection molding polypropylene, which is the plastic normally used for lab and medical equipment. This plastic has a low surface energy and as such it is hydrophobic and lipophobic, for cleaner operation. The three way valve and syringe are both (medical grade) polypropylene as well, which is chemically resistant and cheap.

Educational Card Game

Outbreak !

Overview

For our safety proposal for the RIVM we said we would make a card game. The game had to be fairly simple to explain and quick to play since few people would otherwise put in the time. Inspired by such games as Boonanza and Sushi Go we quickly made a game where you would play dairy products worth some points and infect the products of other players to make them worth less.

It worked pretty well but it was deemed to be more fun than educational, especially after talking again to Jaco Westra. So we went looking for a different type of card game, a so called "serious game". First we had the idea to make an RPG style game more akin to Munchkin, where you would level up your "preparedness" to win and defeat synthetic biology inspired threats as a stakeholder. Preferably in a cooperative way, but making card or board games cooperative is a challenge in and of itself.

This proved to be way too much work and we needed help in design. We went to talk to Ferdinand van der Graaf who is a researcher and a teacher, and has incorporated games in his lessons to teach about evolution. This proved to be very fruitful and we talked at length about game mechanics and how they interact. The most important points he made were:

• Don't think too much about the "serious gaming" aspect, if a game isn't fun enough to play there's no point.
• Especially children read fluff (the little info text on cards) text and take it to heart.
• To make a game coop you must include some mechanism external to players (something we did not end up using).
• To keep as close as possible to an existing game, since those games are already fun and balanced.
• To look at Machiavelli for inspiration, instead of a RPG game.

With this information we went back to the drawing board and made a completely new game. In this game you have to think about which stakeholder you want to be before the round starts and which other players want. As a stakeholder you then can play cards in 3 different areas: Regulations, Opinions or Research. You win the game if you get more than a certain amount of these. The game can be played with 3 to 6 players, and takes about 30 minutes to explain and play in one setting

The game as it is meshes quite well with the RIVM theme of "Think before you do", we presented this at the Kennisparade too. Of coarse we wanted to print it professionally, including fiches and instructions.