We provide an easy method for fluorescence detection and analysis.

We wanted to design a practical test strip for everyone. But how, when superfolder GFP is the ideal reporter protein for in vitro protein synthesis (Lentini et al, 2013 )? It is not visible to the naked eye. Therefore, we designed a device to detect fluorescence. We researched previous iGEM projects with comparable needs and intentions, e.g. iGEM Aachen 2014. They used a filter in front of a sensor to detect fluorescence. But it did not work sufficiently. Another approach is to put a filter in front of the flash, as described by Hossain et al, 2014 . They analyzed a photo that had been taken with a smartphone camera.

Both approaches use only one filter, while both emission and extinction require different filters. The usage of two filters on a smartphone with seperate camera and flashlight, one filter for emission and one for extinction, is our new approach. Now we can detect the fluorescence specifically and display it on an image. Nevertheless, it is still not practicable for the user. So we decided to develop a smartphone app for the analysis of the fluorescence as output signal. You only have to take a photo with two filters attached to your smartphone and the app analyzes it and displays information about the substances that were detected, as we have shown for our cell free biosensors detecting several combined heavy metals and date rape drugs.

Furthermore, it is important to take the photo in a dark environment. Therefore, we designed a small box in which the test strip can be placed. This box enables a suitable positioning of smartphone, filters and test strip. The box can be 3D printed and is therefore cheap and easily customizable.

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