Molecular sensing plays a crucial role in biomedical, chemical, and environmental applications. Traditional plasmonic sensors based on surface plasmon resonance offer excellent sensitivity but face limitations in molecular specificity, scalability, and real‐time operation. Here, we present a novel plasmonic chiral metasurface sensor fabricated via a scalable bottom‐up approach using Layer‐by‐Layer (LbL) assembly and grazing incidence spraying of silver nanowires, and which exhibits a strong circular dichroism (CD) signal. Once integrated into a microfluidic flow cell, the sensor enables real‐time spectroscopic measurements with high stability, reproducibility, and reusability. Refractive index sensing reveals a sensitivity based on the wavelength of the peak in the CD spectra of ∼56 nm·refractive index unit (RIU) −1 and a sensitivity based on the CD intensity at a fixed wavelength of ∼18 700 mdeg·RIU −1 , yielding a limit of detection as low as 1.6 × 10 −4 RIU, i.e. 20 times lower than the conventional extinction‐based methods. Moreover, the device enables in situ monitoring of polymer adsorption throughout the LbL assembly process, thereby providing a highly sensitive and label‐free method for investigating interfacial phenomena. The present work establishes a robust and scalable platform for optical sensing by integrating the distinct advantages of chiral plasmonic materials with real‐time fluidic control and cost‐effective fabrication methodologies.
Veysalova et al. (Sun,) studied this question.