Long Period Fiber Grating as Immunosensor: Picomolar Detection of Immunoglobulin G

A long period fiber grating was fabricated, characterised by the maximum enhancement of the evanescent field by means of the exploitation the lowest order LP0,2 cladding mode (CM) near turn-around point (TAP) in water medium. A thermostated closed flow cell was designed for sensor characterization and immunoassay implementation. The sensor was characterized by surrounding refractive index (SRI) sensitivity within RI range from 1.333 to 1.3335 and the sensitivity was found to be 8751 nm/SRIU with a resolution of the order of 10-5. Immunoassay was performed by immunoglobulin G/anti immunoglobulin G (IgG/anti-IgG) interaction in human serum and a limit of detection (LOD) of 0.16?ng/ml (1.06?pM) was achieved. ? 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.