CMOS-compatible titanium nitride-based grating-coupled NIR SPR sensors for bio-sensing

Surface plasmon resonance (SPR) sensors built on metallic gratings offer a promising platform for highly sensitive, label-free biosensing, chemical and gas spectrometry, biomedical imaging, and diagnostics. Although conventional noble metals, such as gold and silver, are widely used, this work explores titanium nitride (TiN) as an alternative plasmonic material due to its CMOS compatibility and enhanced durability. We introduce SPR sensors with semi-circular and triangular grating nanostructures. With a period of 520 nm for the semi-circular and triangular gratings, the sensors are designed to operate effectively in the near-infrared (NIR) region. Our findings demonstrate that the semi-circular grating configuration achieves a sensitivity of 527.6 nm/RIU with a figure of merit (FOM) value of 199.094 RIU −1 . The triangular grating design yields a FOM of 197.856 RIU −1 with a sensitivity of 515.7 nm per refractive index unit (RIU), comparable to or exceeding the performance of several conventional grating-based sensors. These results underscore the significant potential of combining titanium nitride (TiN) with specifically tailored non-standard grating profiles to develop next-generation surface plasmon resonance sensors with enhanced performance and practical viability in bio-sensing applications. While the proposed designs exhibit promising theoretical performance, the results presented are simulation-based and require experimental validation. Practical realization faces fabrication challenges in achieving sub-wavelength, non-standard profiles with high uniformity over wafer-scale areas, and future work will focus on optimizing fabrication protocols and experimentally demonstrating the sensing performance.