This paper presents a multi-functional operational diagnostic lab-on-foil analysis system integrating electrical and optical devices by polytronic means. This functional polymer-opto-electronic module is completely integrated on a foil substrate, where an electroluminescent light source has been hetero-integrated together with an organic thin-film field-effect transistor (OTFT), working as a photodetector. This module is combined with a microfluidic channel also machined in plastics to form an optical detection system for analysis of fluids. The different components are fabricated on a PEN film substrate with coating and patterning steps, resulting in direct integration of the different functionalities without any assembly steps. Therefore a very cost-efficient way of fabricating such a module is achieved. Furthermore the use of plastic films as substrate opens the way to low-cost manufacturing with roll-to-roll processing. The module demonstrates in this way the capabilities of polytronics in functional integration for low-cost manufacturing.