Arsenic Prototype 4.0

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Revision as of 00:12, 19 November 2015 by Derishus (Talk | contribs) (Principles)

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The Arsenic prototype v4.0 is the Winter School 2016 kit version of [Arsenic-Prototype-3-0 |prototype 3.0].

is based on a fluorescent method where we use GMO bacteria expressing GFP (Green Fluorescent Protein) in presence of Arsenic in a water sample. This fluorescence is detected optically and can be quantified in order to measure the concentration of Arsenic.

A vial containing the water sample we want to test is positioned on a socket through which a blue LED passes. GFP absorbs this blue light (λ=475 nm) and emits green light (λ=504 nm) which is detected by a photosensor on which the light is concentrated with the help of two lenses that avoid loss of intensity and that allow more precise results.

Moreover, a red LED was added to measure the turbidity. Turbidity is the cloudiness or haziness of a fluid caused by individual particles. In our case, if there are a lot of GFP, one GFP can absorb light emitted previously by another GFP and then emit light itself and thus creating a chain reaction falsifying the results. The measurement of turbidity will allow us to normalize our results.

With these measures, one can determine the concentration of arsenic in the sample and so know if the water is drinkable or not.

In summary, the most current version consists of:

   lasercut chassis
   blue LED for eGFP fluorescence excitation at 90 degrees from detector
   red LED for transmittance measurements in line with detector
   vial holder matching the vial approved by the Swiss authorities
   light to frequency detector
   a filter to block excitation light
   LCD screen read out
   based on the arduino


Step by Step Buildling

Laser Cutting Parameters

a chez hackuarium - laser cutter model:

particle board A particle board B

Material: particle board
mode speed power scan mode interval
Groove LED (fluo) scan 50 (100) 35 x_unilat 0.1
3mm board cut 15 100
Text and Logo scan 250 (100) 25 x_unilat 0.3
Groove Lens scan 50 12 x_unilat 0.1
2mm board cut 35 100

Links other References