Last week, we met twice to discuss what we have found in our previous researches and which direction we want to take for the following of the project.
We listed many ways to measure Arsenic in water or E.Coli presence (which is a good indicator of fecal contamination) and found that many methods use fluorescence to detect these pathogens. A resume is there: MethodsEColiAs.
We decided to build a device that would be able to detect fluorescence, a spectrophotometer. Then, we can test what is best detected with (E.Coli or GFP from Arsenic reporter) and prospect in this direction to calibrate and ameliorate our device. We really want to build something and provide information about the building because we think that it will allow other people to build one too. And if people build a device and go in the field to test it, maybe they won’t precisely know the quality of the water they measure, but they will spend time caring about water quality. We think one purpose of the project is also to raise awareness about water quality.
Building a spectrophotometer is, in theory, not that difficult. We need a light source (395nm if we want to measure GFP, 280nm if we want to measure E.Coli), a place to hold the sample, a receptor, an amplifier/transducer, and a read-out. Building a first prototype will be our project for the next three weeks, as well as growing bacterias for the first measures.
Regarding the direction we want to take afterward, we see that if we take the Arsenic-GFP-reporter direction, the challenging part will be to find a good sample-holder. We do not want to use to much GMO to measure Arsenic, but we need a sufficient signal to have precise data about Arsenic concentration… and we also have to think about the problem of the waste produced while measuring!
biodesign for the real world 
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