Femtosecond laser inscription of FBG in novel multifunctional fibre

Femtosecond laser fabrication using the plane-by-plane technique is a transformative approach for inscribing Fibre Bragg Gratings (FBGs) in polymer fibres, enabling advanced biomedical device development. This work investigates the application of this technique in multi-functional polymer fibres that integrate electrodes and microfluidic channels, addressing the unique requirements of medical diagnostics and treatment. The plane-by-plane femtosecond laser method allows precise modification of the refractive index with high spatial resolution, enabling robust FBG structures while preserving the functionality of embedded components. This study employs polymer fibres, that incorporate a polycarbonate core, which exhibit superior flexibility, low Young's modulus, and biocompatibility compared to conventional silica fibres, despite the optical loss. Such characteristics are critical for in vivo medical applications, particularly in minimally invasive procedures. The femtosecond laser ensures submicron accuracy during grating inscription, while maintaining fibre integrity through coatings and the final device was characterized for temperature. Integrating these fibres into medical devices enables simultaneous physiological monitoring, fluid delivery, and electrical stimulation. Applications span from neural probes for temperature and pressure monitoring to lab-on-fibre systems for biochemical sensing. The potential of femtosecond laser-fabricated polymer fibres as multi-functional platforms for medical innovation, setting the stage for compact, efficient, and reliable integrated device solutions.