Optical Slot-Assisted Metasurface for IgG Protein Detection

The sensing of antigens plays a pivotal role in the early diagnosis of tumors by potentially revealing specific biomarkers associated with them. Early detection of tumors can facilitate targeted and less invasive therapeutic strategies. In the realm of Immunoglobulin G (IgG) protein detection, a high concentration may indicate tumor lesions or the presence of symptoms commonly detectable just through invasive diagnostic methods. IgG detection is feasible in blood samples or other biological fluids like saliva or urine. These non-invasive tests offer the advantage of being repeatable over time, reducing the need for invasive or painful procedures. In the pursuit of next-generation medical technologies aimed at flexible and compact sensing platforms, we proposed a refractometric system mainly based on a dielectric metasurface, operating at about 780 nm, featuring a 2D distribution of cells composed of dimers that support the optical slot effect. This effect allows for a large Q-factor, with a small footprint, and strong spatial confinement. Specifically, a Q-factor of 3.19 x 103 with a significant amplitude (> 0.7 a.u.) enables a sensitivity of 25 nm/RIU for IgG protein detection.