High-resolution and temperature-compensational HER2 antigen detection based on microwave photonic interrogation

The human epidermal growth factor receptor 2 (HER2) is a clinically significant molecular marker of breast cancer. Interrogation of a high-resolution and temperature- compensational HER2 antigen biosensor based on a microwave photonics filter (MPF) is proposed and experimentally demonstrated. A microfiber Bragg grating (mFBG) and a regular fiber Bragg grating (FBG) are used as a sensing probe for HER2 antigen-antibody specific binding detection and for temperature compensation, respectively. The key point of this work is to use the frequency domain interrogation scheme based on an MPF for high resolution biosensing detection. Experimental results show that the frequency shift of an MPF notch has a linear relationship with the surrounding refractive index (SRI) change over a range from 1.332 to 1.352, with an SRI resolution up to 2.45 × 10−6 RIU, which is almost three orders of magnitude better than that based on the conventional wavelength interrogation technology (2.9 × 10−3 RIU) using the same sensing probe. In situ monitoring is achieved with a limit of detection (LOD) up to 50 ng/mL, with temperature self-compensation ability. The proposed frequency-domain interrogation method based on microwave photonics opens up a new way for fiber-optic biochemical and environmental measurement.