The idea behind this circuit was to model the detection of the fluorescence emitted by the bacteria: if we apply an intense source of light directly to the light-to-frequency converter (which is the same than the one used in the prototype), it models a great intensity of green fluorescence (and thus supposedly a large concentration of Arsenic in the sample). If no light is applied, the light-to-frequency converter only senses ambiant light which models the situation when the concentration of Arsenic is so low in the sample that not much fluorescence is emitted by the bacteria.
The basic components of this circuit are the light-to-frequency converter (TL235), a piezo speaker (to produce sound) and the arduino manage the input and output of the components. We also added a RGB LED to keep visual information, two potentiometers to modulate the sound produced by the piezo and two buttons to be able to choose two different musics.
The LFT sends a squared frequency signal to the arduino. The file Counter.cpp counts the number of time the signal goes from 0 to 1 and it is this number of counts we compare to a threshold to determine if the light intensity (imaginary arsenic concentration) is acceptable or not. Our prototype shows here a limit because the threshold has to be adapted to the light intensity of the environment where the device is being used.
This prototype is the one we presented at the STIL
Here is the fritzing scheme of the circuit :
the arduino code : https://github.com/biodesign-coco/Sonification/tree/Music-Box
(don’t forget to add the MusicPlayer library)
the README of our circuit (also on Github):
README prototype arsenic sonification
Unzip Music_Box.zip and open the MusicBox.ino file in the Arduino Software. Branch the USB cable of the Arduino to your computer.
Click on Verify and Upload on the Arduino software and read the following instructions :
HOW TO USE IT
1) When you push the button, the device starts counting light intensity.
You will hear a specific while the device is counting (Pirates of the Caribbean)
2) When it is done counting, a different music is being played depending on the measured light intensity:
– If the number of counts is over 900000, the LED is turned ON and
the music being played is stressful (if there is a strong light intensity, it
should mean in the final prototype that the arsenic concentration is too high in the sample).
– If the number of counts is below 900000, the LED is not turned ON and the music
being played sounds less stressful. It means that the arsenic concentration is below
the dangerous threshold.
3) After hearing the second music, you can push the button and the counting will start again.
4) You can also turn the potentiometers :
– to increase or decrease the volume of the piezo speaker
– to increase or decrease the speed of the
(only for the music when the prototype is counting).
note: if you want to test a strong light intensity, you have to add a source of light in front of the light-to-frequency converter (from your mobile phone for example).