The target of the present research is the design, implementation and characterization of a portable device based on an all-optical technology capable to perform simultaneously esophageal manometry, pH-metry and bilimetry by means of a single or combined catheter (OPTIMO project). It will provide physicians a compact and reliable tool to perform exhaustive diagnosis in gastroesophageal reflux pathologies. It would be definitely an innovative product in the gastroesophageal diagnostic scenario with high potential for worldwide market penetration and application developments. In particular, pressure measurement along the esophagus is performed with an array of optical fiber gratings, which ensures the monitoring along a length of about 30 cm with high spatial resolution. The sensors for the measurement of pH and bile are based on the change in absorption caused by the parameter under investigation. In the case of pH, an acid-base indicator that changes its absorption as a function of pH is immobilized on controlled pore glasses suitable coupled to plastic optical fibers. As for bile detection, the measurement is based on the direct absorption of bilirubin, the main biliary pigment, and a bundle of plastic optical fibers carries the signal. With a planned clinical assessment of the realized device, the achievement of this main objective implies the accomplishment of the following sub-tasks: i) development of optical fiber sensor for the measurement of pH; ii) development of the optical fiber sensor for bile detection; iii) development of the optical fiber manometer; iv) integration of the optical fiber sensors within a single catheter; v) realization of the portable interrogation unit for all the three parameters; vi) clinical assessment of the final device on both volunteers and patients.