We provide an easy method for fluorescence detection and analysis.

We wanted to design a practical test strip for everyone. But how, if superfolder GFP is the ideal reporter protein for in vitro protein synthesis, but is not visible to the human eye under normal conditions (Lentini et al, 2013 )? 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(Hossain et al, 2014 ). In this study a photo that had been taken with a smartphone camera was analyzed.

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

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

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