Whether a patient is in an ambulance, emergency room or hospital, point-of-care diagnosis of cerebrovascular disease could soon be possible with a novel biosensor system that uses photonic crystal technology. The P3SENS consortium was formed to develop an immunoassay detection device suitable for emergency stroke diagnosis. Co-funded by the Seventh European Union Framework Program, the €3.6 million project anticipates that the combination of highly sensitive photonic crystals, a panel of clinically proven biorecognition elements, and low-cost production technologies will result in a biosensor system that can make a real difference to stroke patients worldwide. A photonic chip fabricated from nanocomposite polymeric materials using highly scalable nanoimprint lithography (NIL) is at the core of the biosensor. Including nanoparticles of metal oxides within the polymers allows the refractive index to be modified so as to optimize the biosensor’s inherent sensitivity. The photonic crystal optical circuitry that is used to route light around the chip and to interact it with the medium being sensed is defined via arrays of features on the order of 100 nm in size. Although a challenge, the optimization of the nanocomposite polymers for both inherent optical properties and processability via NIL has been tackled by the consortium. An imprinted structure in a polymeric high-index nanocomposite thin film. Courtesy of Multitel asbl. 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. The findings show that the refractive index of the polymer can be increased significantly by the incorporation of the correct nanoparticles. Thin films ( By showing the development of new materials suitable for the production of polymer photonic crystals, the consortium has moved toward its goal of producing a biosensor platform and demonstrating applicability in the point-of-care diagnosis of strokes. It will continue its multidisciplinary approach by driving forward development in polymer materials, photonic crystal fabrication, optical and fluidic systems, and biomedical proteomics.