PVC Detection through a Hybrid SEIRA Substrate and Refractive Index Sensor Based on Metamaterial Perfect Absorbers

Chieh-Ting Lin,Ta-Jen Yen,Tsung-Yu Huang

doi:10.3390/coatings11070789

Chieh-Ting Lin, Ta-Jen Yen + Show 1 more

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https://doi.org/10.3390/coatings11070789

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Abstract

Simultaneous surface enhanced infrared absorption (SEIRA) with Fano resonance and refractive index (RI) sensing are proposed via a split-ring-resonator-based metamaterial perfect absorber (MPA) to detect polyvinyl chloride (PVC), a commonly used polymer but one that was recently prohibited in many areas such as Europe. This bifunctional sensor could provide a label-free and qualitative PVC detection through SEIRA coupled to the vibration mode and a quantitative measurement through RI sensing. To design the MPA, the main operating frequency is targeted at 615 cm−1 for C-Cl bond of PVC. Transition from a reflectance dip to a peak, i.e., Fano resonance was observed at y polarization in both simulation and experiments, evidencing the existence of PVC. On the other hand, to test the RI sensing ability of the MPA, different RI (from 1 to 1.5) of analytes and different thicknesses (from 109 to 1050 nm) of polymethyl methacrylate (PMMA) were applied to the MPA in simulation and experiments, respectively. The simulated sensitivities are 4045 and 2361 nm/RIU for the first and third modes of the MPA, respectively, while the measured sensitivities based on PMMA are 3713 and 1694 nm/RIU. Overall, the detection limit of PVC could be down to 0.5% in experiments, which outweighs the current measurement limit of 10% through infrared absorption measurement.

Highlights

To date, infrared (IR) absorption spectroscopy has been sophisticated and welldeveloped technique that is widely employed for the detection of functional groups, i.e., a molecule’s “finger print”
refraction index (RI) sensing of plasmonic structures is being found in many different research fields such as bio-sensing [9,10,11], bio-imaging [12,13] and chemical detection [14,15]
There appear to be many different plasmonic structures such as nanoscale particles/metallic islands [18,19] or metamaterials [20,21,22] used to create hot spots, achieving surface-enhanced infrared absorption (SEIRA) and RI sensing with higher sensitivity

Summary

Introduction

To date, infrared (IR) absorption spectroscopy has been sophisticated and welldeveloped technique that is widely employed for the detection of functional groups, i.e., a molecule’s “finger print”. The weak intensity of a molecule’s IR absorption signal degrades the sensitivity of the sensor and reduces possible applications of single-molecular detection. SEIRA with Fano resonance provided a label-free molecular detection with higher sensitivity.

Results

Conclusion