Abstract
In this study, we propose a biochemical sensor that features a photonic cavity integrated with graphene. The tunable hybrid plasmonic-photonic sensor can detect the molecular fingerprints of biochemicals with a small sample volume. The stacking sequence of the device is “ITO grating/graphene/TiO2/Au/Si substrate”, which composes a photonic band gap structure. A defect is created within the ITO gratings to form a resonant cavity. The plasmonic-photonic energy can be confined in the cavity to enhance the interaction between light and the analyte deposited in the cavity. The finite element simulation results indicated that the current sensor exhibits very high values in resonance shift and sensitivity. Moreover, the resonance spectrum with a broad resonance linewidth can identify the molecular vibration bands, which was exemplified by the fingerprint detections of protein and the chemical compound CBP. The sensor possesses an electrical tunability by including a graphene layer, which allowed us to tune the effective refractive index of the cavity to increase the sensor’s sensing performance. In addition, our device admits a phononic bandgap as well, which was exploited to sense the mechanical properties of two particular dried proteins based on the simplified elastic material model instead of using the more realistic viscoelastic model. The dual examinations of the optical and mechanical properties of analytes from a phoxonic sensor can improve the selectivity in analyte detections.
Highlights
The wavelengths of light absorbed by many molecular vibration modes and chemical bonds fall within the 3–20 μm infrared (IR) bands, and IR spectroscopy has been a popular technique for identifying the functional groups and fingerprints of biochemicals [1]
The elastic wave of external excitation was applied to perform the phononic sensing of two proteins, namely collagen and HIV-1 protease, which was characterized by different resonance shifts
HIV-1 protease, that is,Inathis smaller added stiffness aand a larger added compared to biowork, we demonstrated graphene-based hybridmass plasmonic-photonic chemical sensor that can be used to detect molecular fingerprints
Summary
The wavelengths of light absorbed by many molecular vibration modes and chemical bonds fall within the 3–20 μm infrared (IR) bands, and IR spectroscopy has been a popular technique for identifying the functional groups and fingerprints of biochemicals [1]. There are many other types of photonic/plasmonic crystals cavities for biochemical sensing, for example, tuberculosis detection based on the photonic bandgap with the blood sample as the defect layer [20], 2-D photonic crystal cavity for cancerous cell detection [21], cancer biomarker detection and drug diagnostics using 2-D silicon PTC microcavities coupled with waveguides in the telecom wavelength band [22], resonance recognition for an artificial organic substance by using 2-D hybrid photonic-plasmonic crystal cavities [23], glucose sensing by placing a dielectric nanowire on the metal grating with a nano-trench cavity [24], and protein detection by using gold gratings deposited on silicon substrate with a graphene-laced cavity [25].
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