Abstract: The present invention provides for the analysis of colorimetric or fluorometric assays by way of capturing an image of the assay on the camera (32) built into the mobile phone (30). A disposable tool (20) is provided to enable the assay to be positioned an appropriate distance from the phone camera (30). A software application on the phone (30) can then analyze the captured image to determinate a qualitative or quantitative outcome of the assay. In many examples, the test will require no modification of the phone hardware and is thus a convenient and cheap technique for analyzing an assay. In other embodiments, other disposable items such filter(s) (41, 42) and/or additional light source(s) (LED 22) may be provided.