Combining our project with the freeze-dried engineering bacteria and East-Wind, we found that our project can be used to detect heavy metals in water. In order to link up all the experimental contents and show you the testing process clearly, we drew a flow chart below.

Here are several possible issues that maybe influence the detection in a real environment. Of course, these variates have been controlled in ideal conditions. You can click here to check our results.
1. pH of water samples
2. Temperature of water samples
3. Colored contaminants and suspended in water samples
4. Establishment of standard curves
5. Biosecurity

To address these issues, we propose following solutions.

1. As we all know, the most suitable pH for engineering bacteria is 6.0-8.0. Through Chinese government’s water-test website, we found that the pH of most water check point is 7.0-7.9, which means our engineering bacteria can grow normally in most cases directly. We can also test the water samples’ pH by using pH test strips. Even if they cannot grow normally due to the pH of water samples, at least the fact has proved that you’d better not drink water here and these water samples are worth having them inspected professionally.

2. Actually we designed a constant temperature circuit in East-Wind. According to the ambient you can choose to use it or not. You can click here to know more about our hardware East-Wind.

3. In the natural environment, the water samples are usually colorless transparent liquid. If the water samples are cloudy, probably because of mud. So just let the water sample sit and take the supernatant to test. If water samples contain colored contaminants, you’d better not drink water here and the water samples are worth having them inspected professionally.

4. Select two microfluidic chips as the control group, add pure water into one chip and standard solution into another. You can compare the data of your water samples with that of the control group to reach your conclusion.

The purpose of our project is definitely not to replace professional testing. If our project can help people make preliminary judgments of water samples and save their time and money, it will inspire us a lot.

5. As we mentioned above, the engineering bacteria are in the state of freeze-dried powder. They have been placed in the microfluidic chips which are hermetic in the laboratory before you use them in practice. The microfluidic chips are disposable, so that they will not be exposed to biological safety problems if you collect them appropriately after using them.