Team:ETH Zurich/bubbling


The bubbling is the starting point of our biosensing pipeline. The goal is to transfer the molecules in air into our medium. This solution is then brought in contact with E. coli on the microfluidic chip. According to the model we can optimize the efficiency when reducing the bubble size and the volume of medium we bubble in. In order to do that we needed to design our own bubbling approach.

The implementation
There are three main components involved. First there is the Air pump. We use a 12V air pump having very high throughput. By only applying a short electric pulse every second we generate the right amount of air pressure for our system. This is then directed to the bubbling chamber. The bubbling chamber is our second part and the main part of our system. Here the air is pumped in and brought in contact with our medium. It is designed in a special way such that the medium does not form spill out of the tank. This is something that could otherwise happen as we need to leave a hole for the remaining air leaving the container. To control the medium in the bubbling container we have three in- and outputs. There is one main input from a large syringe pump, adding new medium before the bubbling step. Then after the bubbling we have one output feeding into the microfluidic chip. Here we measure only a small percentage of the total volume of roughly 1ml. The rest is sucked out through the last output, going into a second large syringe pump which then holds the waste solution.
This process is optimized to run on the Robot. As we want the distance from the bubbling chamber to the microfluidic chip to be as small as possible we placed it right next to each other. As we can not pull our medium quickly through the microfluidic chip (in order not to disrupt the E. coli) it takes quite some time until the medium form the bubbling chamber arrives at the microfluidic chip. As we reduced that size we only need to suck in the medium for around 15 seconds. Nevertheless this could be further improved.
Bubbling a molecule from the air into solution is a common problem and has been solved before. We focused on the implementing our own system to optimize speed and concentration of the bubbled solution. A detailed description about the optimization can be found on the model page.
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