The P3SENS consortium has been formed to develop an immunoassay detection device suitable for emergency stroke diagnosis. Co-funded by the Seventh EU Framework Program, the €3.6 million project will develop photonic crystal technology for point-of-care diagnosis of cerebrovascular disease, whether the patient is in an ambulance, emergency room or hospital. It is anticipated that the combination of highly sensitive photonic crystals, a panel of clinically proven biorecognition elements and low-cost production technologies will result in a novel biosensor system that can make a real difference to stroke patients worldwide. Shown is a nanoimprinted structure in a polymeric high-index nanocomposite thin film. At the core of the biosensor is a photonic chip, which, because of the cost restrictions of point-of-care applications, is to be fabricated from nanocomposite polymeric materials using highly scalable nanoimprint lithography (NIL). The optical properties of the polymers are defined by the nature of the nanoparticles included within them; the use of metal oxides allows the modification of refractive index required to optimize the inherent sensitivity of the biosensor. The photonic crystal optical circuitry used to route light around the chip, and to interact with the medium being sensed, is defined via arrays of features of the order 100 nm in size. Optimization of the nanocomposite polymers for both inherent optical properties and processability via NIL presents a significant challenge, which the P3SENS consortium has tackled head-on. A range of polymer host materials and nanoparticles have been screened to identify suitable systems for the formation of nanocomposites and subsequent processing via NIL. It has been shown that the refractive index of the polymer can be increased significantly by the incorporation of the correct nanoparticles. Thin films (below 500 nm) of polymeric materials with a refractive index of up to 1.74 have been prepared. Moreover, initial tests indicate that the high-index nanocomposites can be structured by NIL. The completion of these significant milestones, showing development of new materials suitable for the production of polymer photonic crystals, is rapidly leading the P3SENS consortium toward its goal of producing a biosensor platform and demonstrating applicability in the point-of-care diagnosis of stroke. The consortium continues its multidisciplinary approach with parallel activities driving forward development in polymer materials, photonic crystal fabrication, optical and fluidic systems, and biomedical proteomics. For more information, visit: www.p3sens-project.eu