A mobile phone-based system for ELISA (MELISA). The MELISA system can perform all steps of ELISA procedure and output hormone concentration values. The system includes a heater that keeps the temperature required for sample incubation, illumination system for sample image capturing, and a digital camera system. All components are enclosed in a dark box to create optimal light conditions for image capturing. After sample images are captured, they are digitally processed, and hormone concentration values are reported based on colorimetric data from the samples. The system can be used to complete all steps of the assay, including incubation and reading. It is lightweight, can be fabricated at low cost, is portable, and can transfer test results via mobile phone. MELISA can be calibrated for accurate measurements of progesterone and has demonstrated successful measurements with the calibrated system.