Team:Sheffield/Demonstrate
Demonstrate
To demonstrate that our device works, we performed a bacterial growth experiment and used our device to detect the changes in turbidity that occurred due to the bacterial growth. As the bacteria grow and the solution becomes more turbid, more light is attenuated as it passes through the sample in the well. The transmittance of light that reaches the photo-diode is therefore decreased and this decrease of light causes the photo-diode to produce less current across it, and therefore the potential across the photo-diode also drops. This change in potential is measured using a potential divider between the photo-diode and a resistor. As the voltage across the photo-diode decreases the voltage across the resistor increases, meaning if the bacteria are growing we will see the voltage across the resistor increasing. This is shown in the graph below:
Figure 1: The Figure above shows a bacterial growth curve that was measured with our device. As bacteria grow and block the light the voltage across the photo-diode decreases and therefore the voltage across the resistor increases. The increase of the voltage across the resistor as the bacteria grow is what we can see above.
The slight unexpected variations are due to noise, however we are able to remove this by smoothing the data. To see more information about this please look at "Smoothing" under the software section. An example of a graph that has been smoothed is shown below:
While we were running this growth experiment in a plate...
What should we do for our demonstration?
Standard teams
If you have built a proof of concept system, you can demonstrate it working under real world conditions. If you have built a biological device that is intended to be a sensor, can you show it detecting whatever it is intended to sense. If it is intended to work in the field, you can show how this might work using a simulated version in the lab, or a simulation of your device in the field. Please note biological materials must not be taken out of the lab.
Special track teams
Special track teams can achieve this medal criterion by bringing their work to the Jamboree and showcasing it in the track event. Art & Design, Measurement, Hardware and Software tracks will all have showcase events at the Giant Jamboree. Please note biological materials must not be taken out of the lab.
