Abstract
We demonstrate a novel, label-free and real-time tunable infrared biosensor by employing surface-plasmon polaritons in asymmetric Mach–Zehnder interferometer. The waveguides cladding in the Mach–Zehnder interferometer are made of lossy media with positive and negative electromagnetic susceptibilities, including metamaterial, metal and graphene. The core consists of dielectric media. We introduce two configurations for our biosensor structure. First configuration is an open-path structure and the second one consists of a sample housing made of a silicon layer around the structure. We also present a tunable biosensor by applying a gate voltage to the graphene in the structure. We employ three different cancerous cells, including cervical, breast and basal, as samples to examine the capabilities of the biosensor. Our biosensor structure is highly sensitive, compared to the existing biosensors in the literature, with the sensitivity for basal cancer cell of 1034THz/RIU. The proposed biosensor structure is compact and easy to fabricate with applications in biomedical sensing and environmental control to detect water pollutants.
Highlights
Lable-free plasmonic biosensors are biological systems that have applications in medical analyses [1], drug development [2], food quality control [3] and environmental monitoring [4]
We demonstrate a novel, label-free and real-time tunable infrared biosensor by employing surface-plasmon polaritons in asymmetric Mach-Zehnder interferometer
Our plasmonic biosensor is sensitive to the changes in the refractive index (RI) of the surrounding media
Summary
Lable-free plasmonic biosensors are biological systems that have applications in medical analyses [1], drug development [2], food quality control [3] and. Different plasmonic structures are employed in the RI biosensors. Mach-Zehnder interferometer provides relatively high sensitivity for the biosensor [9] that makes MZI a suitable sensing platform for biomedical applications [10]. The sensitivity of a MZI-based sensor varies depending on the characteristics of the device such as its media and size [11] These plasmonic biosensors based on MZI are capable to detect and identify various samples with different RIs, including cancer cells [12]. The design of graphene-based plasmonic biosensor proposes a combination of plasmonic response of graphene and metal to improve light-matter interactions. To examine the specificity of the biosensor structure, we employ cancer samples with RIs near to some normal cells with high growth rates.
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