Team:IISc-Bangalore/Hardware/GCODe-Pro
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GCODe Pro
What is it?
The Mini’s bigger sibling, the GCODe Pro, was designed to overcome most of the limitations of the Mini. The Mini is incredibly useful in its own right, but it lacks the capability to handle larger volumes of culture or dilute samples. The Pro, however, has the capability to draw a precise volume of sample, dilute it to the required concentration, and measure its optical density. The culture can be kept in a standard conical flask inside the shaker, with only a tube going into the flask. This means that the Pro can be used for a much larger variety of applications, such as quantifying bulk extraction of protein, and with a vast range of microorganisms, even yeast, which can grow to ODs of 1000 or more.
Cost
The Pro is an ambitious project since it aims to do what the best automated growth curve machines do and more, for a price that is literally two orders of magnitude lower. It costs less than $250 USD versus $25000 for the Bioscreen C, a well-known automated cell culture system. We went to great pains to make GCODe as cheap as possible, by avoiding expensive techniques such as 3d printing and favouring low-cost and widely available components, such as the Arduino, and simple servo motors. We also tried hard to minimize the number of expensive components, for example, by redesigning our fluidic network to use only one peristaltic pump.
Development Status
The project is still in the beta testing stage, and we have uploaded all the resources required to develop the project to the current stage, so that anyone can build and contribute to the Pro.
What can it do?
The GCODe Pro has all the functionality of the Mini, like automatic OD measurements, real-time growth curve plotting, and pushbullet alerts. Apart from this, the Pro can:
- Dilute a sample to a specified concentration
- Add reagents to the sample before OD measurement
- Maintain sterility through an ethanol-flushing mechanism
- Turn the shaker on and off automatically when it needs to take a sample
How does it work?
Parts
The Pro consists of 5 different units, represented in the flowchart below:
| Unit | Function |
|---|---|
| Power Unit | The power unit is responsible for turning the shaker OFF during measurement, and ON when it is not measuring. |
| Sampling Unit | The Sampling Unit handles the fluidics. It is responsible for all the fluid transfer processes that happen during measurement. Fluid flow is controlled by a peristaltic pump and several servo motors connected to one stopcock each |
| Mixing Unit | The mixing unit is a container in which the Sampling Unit mixes and dilutes fluids. It also acts as a buffer for fluid transfer. |
| Flask Unit | The flask unit is the part which goes inside the flask in the shaker. It contains the tubing to draw sample from the flask. It also contains the tubing required for the cleaning mechanism. |
| Analysis Unit | This is where the actual OD measurement happens. It consists of an LED-photodiode setup similar to the one on the Mini. |
Mechanisms
The GCODe Pro mechanisms can be broadly divided into Fluidics, Electronics and Optics. The Fluidics is controlled by a system of tubes and servo motors attached to three-way stopcocks and a single peristaltic pump. The electronics is controlled centrally by an Arduino Uno and a few PCBs that were designed for specific purposes. The Optic system is similar to the one on the Mini, using an LED and a Photodiode. The pump and the servos are connected in a way that enables all the fluid transfers we need using just one pump, for economy. The schematic for the fluidics is shown below.
The sample is drawn to the Mixing Unit, where it is mixed with the required amount of water to dilute it to the specified concentration. The diluted sample is then drawn to the cuvette sitting in the Analysis Unit, where its OD is measured. After measurement, the fluid in the cuvette and leftover fluid in the mixing unit is discarded. Finally, the ethanol flushing mechanism loops around the flask unit pipe to sterilize all the tubing.
How much development is complete?
The GCODe Pro is still in active development. While the machine achieves all the sample drawing, transferring and OD measurement seamlessly, and is calibrated for linearity of OD readings, the ethanol flush mechanism still needs to be tweaked. Of course, the machine still needs to be tested for sterility, used to run sequences of growth curves in-house and fully documented before it can be sent out into the wild.
Are you interested in building your own GCODe Pro Beta version? It's an ambitious project, and we need all the help we can get. You can contribute to the project by developing the Pro further. Simply visit our Build Your Own page to access all the current documentation.
