Team:Amazonas-Brazil/Hardware
An incubator is a machinery that has as its primary function offer ideal conditions to the reproduction and development of an organism, such as Cells and Tissues, which mainly need conditions different from those encountered in common environment.
A CO2 Incubator has as it main directive the development and maintenance of an environment with ~5% CO2 and 37°C (98.6°F), conditions ideal for common cell culture. With these conditions meet, it will be possible to culture and maintain cells, should they be human or otherwise.
When we first designed our project, we realized that an incubator would be a useful device for eventual experiments and characterizations. However, neither our lab group possess one, nor our neighbor’s labs did. After searching for commercial incubators, we found that it would be very expensive to afford a new one, but that it was possible to build a home-made device that could work pretty well as the commercial. So, why not try to build one?
Theoretical Reference
CO2 incubators are usually used in high-level research, like the ones focused on public interest topics, such as cancer and neural diseases, and as they are very expensive to buy and maintain, which restricts its use, alternatives such as CO2 free media, like HEPES or Leibovitz-15, exist but are still cost restrictive.
A cheaper option is to use the “Candle in a Jar” method, which utilizes à common candle in a sealed space and most of the time a glass jar. Even though this option allows us to produce and maintain a ~5% CO2 environment, the level of CO2 is not constant and the size of the jar limits cell growth in the culture environment. With those issues in mind, it was made the decision to build a DIY CO2 incubator following some principles that guided us to make not a commercial-model-alike but something that works for us and hopefully for other teams.
PRINCIPLES:
- Thou shall be of low cost
- Thou shall be trustworthy and easy to make
- And least, but not last, Thou shall be portable
Designs
Version 1- A big jar with loads of candles
The first design made was based on the “Candle in a jar” concept, just bigger. The initial plan was to use an Aquarium gently donated by a team member to be the base of the design. Since it was made of glass it presented an advantage if compared with other models, which was the possibility to see the system and the cells 24/7 easily.
The CO2 would be produced with a bundle of common candles, the CO2 level would be verified with the MQ-135 CO2 sensor and an Arduino and showed by a LED display. We thought about only using candle to reach and maintain the 37°C needed, but after some number crunching and simulations by our modelling team, the Idea was abandoned and favored by using a common lamp to use as heat control.
Fig 1: Design made with the Free to Use Software Energy 2D
Fig 2: Design made with the software SmartDraw
Version 1.1- Failure in details
- Cost. Since we would use an aquarium as the base, the cost of the project was heavy and prone to disaster if any sort of accidents happen.
- Thermal Isolation. Glass is a good heat conductor and as such would present some difficulties to control its internal temperature, raising the work involved and energy costs.
- Personal Risk. While the use of candles was seen as acceptable and without major risks by some researchers, it was seen as an unnecessary risk by the Hardware Team since a constant switch of candles is necessary to long-term maintenance of the system.
- Contamination. One of the biggest problem in cell culture is contamination from bacteria and fungi, the constant switch of candles would generate a lot of opportunities to contamination to growth.
Version 1.2 Problem solving
It was studied and discussed detaching the CO2 producing from the main body of the incubator, and a experimental design was made. In this idea, a candle would be isolated in a separate jar, which would be connected to the main unity through a pipe, for the control of gas pressure, a valve would be used.
Fig 3: Design made utilizing the Software SmartDraw
The idea was discarded after we noticed it would raise costs and lower portability and confiability of the system, and would only solve some problems of hardware. It was then evaluated if the candle system would be substituted by a chemical CO2 producing one made by the mixture of vinegar and sodium bicarbonate. This idea was the one that inspired the 2.0 version.
Version 2- Adapt, Survive, Overcome.
With a new development cycle, a new design was made this time with some different approaches to tackle problems previously found in old designs.
The aquarium was substituted by a common ice box, as is cheaper and providing better thermal isolation. The CO2 system was made by a chemical one, by the reaction of vinegar and sodium bicarbonate. A cooling system was added to help heat regulation (Which is extremely necessary in the middle of the amazonian summer, when temperatures are constantly higher than 37°C/98.6°F) and two small coolers were added to create an internal air flow and to help stabilize both heat and CO2 distribution.
Fig 4: Design made in the software SmartDraw
Fig 5: 3D model of the CO2 incubator, made in the CAD software SketchUp.
Fig 6: 3D model of the CO2 incubator, made in the CAD software SketchUp. This model was made solely to help the Hardware team visualize the incubator and how any changes could impact it.
Fig 7: The modelling of our Arduino circuit, made in TinkerCAD.
| Product | Quantity | Value in Reais (R$) | Total Value in Reais (R$) | Value in Dollars (US$), Direct exchange |
|---|---|---|---|---|
| Arduino UNO | 1,00 | 50,00 | 50,00 | 11,36 |
| Peltier Coldener | 1,00 | 30,00 | 30,00 | 6,82 |
| Relay module 5V 4 points | 1,00 | 28,00 | 28,00 | 6,36 |
| Dissipator disk | 1,00 | 5,00 | 5,00 | 1,14 |
| 30W Solder | 1,00 | 38,00 | 38,00 | 8,64 |
| Dissipator disk | 1,00 | 5,00 | 5,00 | 1,14 |
| Heat display | 1,00 | 15,00 | 15,00 | 3,41 |
| Display LCD 16X2 | 1,00 | 20,00 | 20,00 | 4,55 |
| Macrodrop | 2,00 | 2,70 | 5,40 | 1,23 |
| 60cm tube | 2,00 | 2,15 | 4,30 | 0,98 |
| Silver Tape 48mmX5M | 1,00 | 12,00 | 12,00 | 2,73 |
| Silicon Glue | 1,00 | 10,00 | 10,00 | 2,23 |
| Fita Silver Tape 48mmX5M | 1,00 | 6,00 | 6,00 | 1,36 |
| Sodium bicarbonate | 7,00 | 0,75 | 5,25 | 1,19 |
| Vinegar | 4,00 | 1,25 | 5,00 | 1,14 |
| Barbecue Grid | 1,00 | 39,90 | 39,90 | 9,07 |
| 24L ice box | 1,00 | 16,90 | 16,90 | 3,84 |
| Total | - | - | 290,75 | 66,07 |
One of the main aspects of our system or even the most important aspect, is how it’s cheap compared to an industrial model. While certainly not even close in quality to a professional made incubator, cheapness is very nice.
Fig 8: The first testing of our CO2 system was just to see if even works, it was very nice to see the CO2 bubbles in a simple cup of water.
Fig 9: Our first contact with an Arduino and with electronics was just as scary as awe-inspiring.
Fig 10: The first test with all parts ready and working
Version 3 - Problems and Solutions
Arduino. While building the system was in fact the simplest part, and making the CO2 production system was a good experience, building the electronic part was a very tricky business since our team has almost no experience working with electronics, specially with an Arduino, but with some help, me managed it.
Leaks. Other problem we faced was leaks, since styrofoam while an easy material to work with, is very fragile, specially with heat, thankfully, silicon glue and silver tape was plentiful to use. Still it provided such a great problem that it was very difficult to use resistors to heat it without causing a meltdown.
Contamination. Contamination was a big problem too, since some of the leaks were found after some time, and as such we experienced some incidents of contamination. They were solved by a more careful decontamination of material that was to be put inside and a regime of more intense cleaning with 70% Alcohol, doing it every time someone opened or operated the circuit.
Valves. One thing that caused us some problems was in the chemical part, where after some use, our system got clogged. The problem was solved after a careful analysis of the system, we found that the tube responsible to collect CO2 was stuck to low and as such, collected droplets of water, just a fast correction and it was resolved.
FINAL REPORT:
Building a Hardware from zero was certainly a very interesting experience to everyone involved, and from everyone who followed it. While not the most advanced or complex hardware, far from it in fact, it got the work done, which was more than enough for us, and we hope the feeling is the same for other teams.
We aim to future improve our Hardware design and continuous make something better and better. And we wish to these improvements not only come just from us, but from other teams, as such we will make available an instruction guide to everyone so they can build their own hardware. Where is it? Right Down below!
And we are ready to help anyone who tries to build their own incubator, send us an e-mail or a message in our social media and we sure help!
Download the guide
HERE!.
