Photonic Devices for Health Applications 

In recent decades, the biomedical research community has increasingly focused on the development and adoption of advanced technologies for the prognosis and diagnosis of a wide range of diseases. Within this framework, the group’s research activities focus on the design and development of innovative and minimally invasive photonic devices.  Among these, a hybrid dielectric-plasmonic nanobowtie device has been designed for the trapping and thermal destruction of biological nanoparticles, demonstrating trapping stability greater than 10 and optical forces of approximately 2.96 fN under an input power density of 10 mW/μm².

Research activities within the laboratory focus on the design and development of photonic biosensors capable of detecting circulating tumour biomarkers in biological fluids. As an initial step in this research, we conducted a comprehensive review of Lab-on-Chip (LoC) systems enabling liquid biopsy, an emerging and minimally invasive diagnostic approach for the highly sensitive detection of tumour biomarkers. The review specifically focused on integrated photonic biosensing platforms within LoC systems, emphasizing their potential for early-stage cancer diagnosis.Among the platforms developed, one is a refractometric sensor based on a dielectric metasurface, which achieves a high Q-factor of 3.19 × 10³, a strong resonance amplitude (> 0.7 a.u.), and a sensitivity of 25 nm/RIU. The device is designed for the detection of IgG proteins in blood, saliva, or urine samples, offering a non-invasive, compact, and highly repeatable diagnostic solution.

Additionally, a versatile dielectric metasurface, consisting of hydrogenated amorphous silicon nanocuboids on a glass substrate, has been proposed and investigated for dual functionality in IgG sensing and optical trapping. Both operations are enabled by the excitation of a high-Q anapole state, which ensures strong field confinement and enhanced light–matter interaction. In the context of sensing, the structure demonstrated a surface sensitivity of 35.13 nm/RIU.

Another developed platform is an ultra-compact photonic biosensor based on a one-dimensional photonic crystal (PhC) with engineered defects, designed to achieve a tailored resonance with a box-like spectral shape. The device exhibits a high roll-off rate (−10.50 dB/oct.), enabling single-wavelength interrogation and minimizing spectral overlap. It achieves a sensitivity of 490.49 nm/RIU and a figure of merit (FOM) of 3892.78 RIU⁻¹. This device consents the detection of Immunoglobulin G (IgG) proteins over a concentration range from 1 to 500 pg/mL, significantly reducing reading errors compared to traditional Lorentzian-shaped resonators.

An additional research activity in the field of biosensing focuses on the design of a hybrid plasmonic/dielectric sensor capable of detecting refractive index variations induced by the presence of biomolecules in biological solutions. The device consists of a plasmonic metasurface (Au) integrated within a silicon waveguide, with a SiO₂ spacer layer introduced to enhance field coupling. This configuration offers several advantages, including straightforward integration, high electric field localization, and strong field enhancement, key features for achieving high sensitivity in label-free biosensing applications.

Among the ongoing activities in the health field, one line of research focuses on the development of optical sensors based on topological edge states. These sensors offer exceptional robustness against environmental perturbations and fabrication imperfections, while maintaining high sensitivity. This is achieved by exploiting strong evanescent fields generated at the interface between two structures with opposite topological phases.

References:

P. Colapietro, G. Brunetti, A. di Toma, F. Ferrara, M.S. Chiriacò, C. Ciminelli, “High Stability and Low Power Nanometric Bio-Objects Trapping through Dielectric–Plasmonic Hybrid Nanobowtie,” in Biosensors, vol.14, MDPI,2024, pp. 390.doi: https://doi.org/10.3390/bios14080390

C.Ciminelli, P. Colapietro, G. Brunetti, M.N. Armenise, “Lab-on-chip for liquid biopsy: a new approach for the detection of biochemical targets,” in 23rd International Conference on Transparent Optical Networks (ICTON 2023), IEEE,July 2023, pp.1-4. doi: 10.1109/ICTON59386.2023.10207546

G. Brunetti, N. Saha, P. Colapietro, and C. Ciminelli, “Optical Slot-Assisted Metasurface for IgG Protein Detection,” in Journal of Physics: Conference Series, vol. 2725, no. 1, IOP Publishing, March 2024, pp. 012001. doi: 10.1088/1742-6596/2725/1/012001.

G. Brunetti, C. Panciera, C. Ciminelli, “Versatile Metasurfaces for Liquid Biopsy Applications,” in 2024 24th International Conference on Transparent Optical Networks (ICTON 2024), IEEE, July 2024, pp. 1-4. doi: 10.1109/ICTON62926.2024.10647788

A. di Toma, G. Brunetti, P. Colapietro, and C. Ciminelli, “High-Resolved Near-Field Sensing by Means of Dielectric Grating with a Box-Like Resonance Shape,” in IEEE Sensors Journal, vol. 24, no. 5, 2024, pp. 6045–6053. doi: 10.1109/JSEN.2024.3349948.