The present application provides a system (1) that comprises a mobile phone (25) to allow testing of samples from a patient at the point of care or environmental/industrial process monitoring tests to be performed in the field. The system (1) may be easily adapted for use with a variety of different mobile phones (25). The mobile phone (25) comprises an integrated camera (15). The system (1) further comprises an optical module (20) for receiving a sample for testing. The mobile phone (25) is configured to extract the intensity and/or color information from the camera (15).