Abstract: Colorimetry is used to detect amplification reaction products. A sample is contacted with a reaction mix under conditions such that an amplification reaction occurs and produces an amplification reaction product if the sample contains a target nucleic acid template molecule. The reaction mix includes an enzyme for catalyzing the amplification reaction, and at least one halochromic agent. If the target nucleic acid template molecule is present, the amplification reaction changes the starting pH of the reaction mix to cause a detectable colorimetric change of the halochromic agent, thereby indicating the presence of the target nucleic acid. If the target nucleic acid template molecule is not present, the amplification reaction does not generate an adequate number of protons to sufficiently change the starting pH of the reaction mix to cause a detectable colorimetric change of the halochromic agent, thereby indicating that the amplification reaction product has not been produced.

Abstract: A diagnostic system performs disease diagnostic tests using at least an optical property modifying device and a mobile device. A user provides a biological sample from a patient to the optical property modifying device that reacts with a reagent in one or more reaction chambers of the device. The user captures one or more images of the one or more reaction chambers using an optical sensor of the mobile device. The diagnostic system can determine a quality level of the images based on factors such as skew, scale, focusing, shadowing, or white-balancing. Based on an analysis of the captured image, the diagnostic system can determine a test result of a disease diagnostic test for the patient. The diagnostic system may communicate the test result, as well as instructions for the disease diagnostic test, to the user via the mobile device.