An additional aim of the project was to make lab material more accessible to all iGEM future teams. In this case, we worked on lowering the price of a medium performance microcentrifuge, most of them costing around 500+ USD, to a cheaper but as effective one for as little as 65 USD.
Lab material is usually really expensive. If it wasn't for the initial cost of this equipment, more students could get thrilled on more areas of synthetic biology. Currently in the market, the lower cost microcentrifuges spin at around 7,500 rpm and its price range is between 500 USD (VWR, 2022a) and over 1,900 USD (VWR, 2022b).
Reaching the goal of this project can reduce the initial expense of a new lab, ultimately leading to more people getting interested on developing more projects and advancements in synthetic biology.
We found 2 comparable microcentrifuge models to the specification range of our product. The first one spins at 15,500 rpm and has a cost of 1,912.68 USD without shipping. The other one spins at 7,500 rpm and costs 513 USD without shipping. Both of them accept 2.0 mL microtubes, while only the high cost one also accepts 0.2 mL microtubes.
Operationally speaking, both models work under the next steps:
All centrifuges investigated do not follow any environmental or disposal terms.
Maintenance instructions on both centrifuges are not shown on the shopping page but might be included as a manual.
The product design specification (PDS) was done trying to solve the expense inaccesibility described above. As well as properly supply the specifications desired by the final user.
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After assembling the microcentrifuge, we ran different samples and recorded their results.
Our first test was dirt and water. Even though we ran it at full speed for one minute, the centrifuge was powerful enough to precipitate the dirt in less than 10 seconds. Here is a video of that experiment:
Afterwards, we compared the performance of our microcentrifuge with a high-end microcentrifuge found at our lab. Both equipments centrifuged E. coli grown in LB broth at full speed (close to 13,000 rpm). As it can be seen on the following images and videos, two tubes were used as test subjects, both filled with 1 mL of cell culture. The one centrifuged with our system had the lid marked with green (left microtube in both images). On the other hand, the microtube to be tested in the lab centrifuge was marked with red (right microtube in both images).
After centrifuging the mictorubes for a total of 6 minutes, both had formed a pellet at their respective bottoms (after testing image). The pellets shown are approximately the same size and adhered to the bottom of the tube even when flipped.
After making sure the centrifuge functioned properly, we visited teachers, specialists, and doctors from our school and receoved feedback from their observations. We wanted both technical and practical feedback, thus we asked experts on diverse fields of study. Here are some of the reviews we gathered:
Ph.D. in Computer Science.
"It should have a more visual way to differentiate when it's done spinning and when it's spinning. You can add different color LEDs to illustrate this. Also, you must cover up the electronics from the user accessible area. Otherwise it could lead to the user disconnecting cables by accident."
Ana Carolina Apodaca
Master in Science.
"It's better for the electronics not to be shown, if one of the microtubes opens for any reason while spinning, this might be a problem. As a future improvement, you could add a refrigeration system inside the case. Some protocols require the environment to be at a certain temperature while centrifuging, therefore, this parameter can be implemented in the prototype. I will use this prototype for simple academic protocols or to illustrate the capabilities of the equipment and how a microcentrifuge works."
Berenice Oseguera
Ph.D. in Biomedical and Molecular Biotechnology.
"I liked it, this centrifuge is very useful for a lot of protocols, it's portable, compact and cute. The next step would be to have a cooling system for complicated practices. Overall, this centrifuge is even better than the smaller centrifuges we own at our lab. Both, the speed and time, can be dialed and accomplishes the requirements for it to work in more complex protocols."
The prototype was made on Fusion 360 and the slicing was done in Ultimaker Cura.
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Each piece was designed and sliced by our team with previous planning. We looked for a friendly design without compromising the quality, durability, and functionality of the microcentrifuge. We came up with embossing our logos and mascot on the sides, making all parts sturdy enough and making a see-trough yet safe for the user lid.
We based our code with a finite automaton. This state machine was made to know exactly what actions can the Arduino execute and how does the user gets to interact with each status.
We can see that the yellow circles represent the status of the Arduino on a more organized and technical way. The arrows represent the connections between each state and tell how the user accesses each position depending on what is the current status.
Figure 1. State Machine created for the operational code.
After we analyzed the previous state machine, we could start working on the code. You can find the full code right here:
The electronics were intended to be controlled with an Arduino Uno and open source components. We used both sensors and actuators for the optimal and correct functioning of the microcentrifuge. The scheme is shown on the next image and has a detailed display on how every component was connected to the main board.
Figure 2. Electronics intereconnections diagram.
The final step was to upload the code and for us to assemble all the printed parts and the electronics.
We printed each part with PLA filament on a 3D printer. Then, we added the electronics and inserted them on the printed parts, adding adhesive clay to secure them in place. Finally, we connected the components and made a test run to ensure everything was working on the intended way.
All our designs, codes and models are open source. Feel free to download the stl files for printing found on the next buttons:
The official microcentrifuge manual describes all the steps done for the project to be completed. You can find our process of modeling, printing, coding and assembling of the entire system along the way for you to have this functional equipment at a low cost: We hope to see your versions of the centrifuge!
