The objective of this project is to develop a miniaturized cheap and disposable photonic device for bio sensing that is capable of performing quantitative diagnostic tests that are currently limited to a hospital laboratory setting. Our target product is a disposable device for monitoring cardiovascular health - an EU-wide healthcare priority. To date Microfluidic (or Lab-on-a-Chip) devices have not been well suited to point-of-care applications. Although the chips themselves are cheap and small, they must generally be used in conjunction with bulky optical light-sources and detectors. The lack of an integrated, versatile detection scheme is a major obstacle to the deployment of portable diagnostic devices. Consortium partners have demonstrated that integration of organic diodes and photodetectors is a viable route to meet this need. The purpose of this proposal is to develop a radically new generation of devices, in which organic photonic field-effect transistors are used for both light generation and detection. The use of transistors in place of diodes has four principle benefits. Firstly they can be pre-fabricated on the substrate (the microfluidic chip), ensuring optimal registration between the organic photonic components and the underlying fluidic architecture. Secondly the devices can be completed by depositing a single layer of organic semiconductor followed by the gate electrode, thus avoiding the need for complex multilayered structures. Thirdly in-plane light generation by the transistors provides improved optical coupling into wave-guiding structures, leading to significant performance gains. And fourthly current-multiplying auxiliary transistors can also be included thereby enabling immediate amplification of the signal at the point-of-generation. In combination these factors offer a compelling solution to the challenge of point-of-care detection that will offer unprecedented sensitivity and superior reliability at a markedly reduced cost