Abstract
In this work, a highly sensitive surface plasmon resonance (SPR) sensor based on a single mode fiber (SMF) incorporating a large microfluidic channel (MFC) for refractive index (RI) sensing is designed and optimized using a full-vectorial finite element method (FEM). The fluidic channel size can be varied according to the requirement due to the availability of the large cladding diameter of SMF, which makes it simple and easy to fabricate. The proposed novel sensor is favourable to both analytes and metallic strips. The D-shaped hollow section above the core is filled with the measurand analytes and a gold (Au) strip is deposited on the base of the MFC, as it is known as the most attractive metal for SPR. Our numerical simulations illustrate that the confinement loss of the designed sensor is highly influenced by the distance of the MFC from the core along with the width and thickness of the Au strip. The designed sensor shows an average sensitivity of 1350 nm/RIU and maximum sensitivity of 8250 nm/RIU in the sensing range of 1.33-1.35 and 1.41-1.43, respectively. However, for a small variation of na at a step of 0.005, within ranges like 1.415, 1.420, and 1.425, we have achieved a maximum sensitivity of 7000 nm/RIU, 9000 nm/RIU and 11000 nm/RIU, respectively. This novel SPR sensor with MFC can open up a new opportunity in the application of chemical and biological sensing.
Highlights
Over the last few decades, surface plasmon resonance (SPR) techniques have achieved considerable recognition because of their salient characteristics in term of sensitivity, label-free detection, fast response time and offer potential application in the field of chemical and biological sensing
We proposed a newly designed SPR sensor based on D shaped microfluidic channel (MFC) for a wide range of refractive index (RI) sensing
Both ends of proposed sensor are spliced with single mode fiber (SMF) of diameter 125 μm using fusion splicer and the liquid is considered to be sealed in the MFC of designed sensor
Summary
Over the last few decades, SPR techniques have achieved considerable recognition because of their salient characteristics in term of sensitivity, label-free detection, fast response time and offer potential application in the field of chemical and biological sensing. In 2015, Patnaik et al introduced an ITO coated D shaped sensor and achieve a high sensitivity of 5700 nm/RIU Their proposed sensing configuration permit higher interaction of light with outer media due to the polished surface and ITO layer [20]. All these sensors are fabricated by side-polishing the cladding of fiber along the half of its circumference in order to form it in D shaped structures These sensors achieve high sensitivity in their respective areas, but they face various drawbacks such as it destroys the circular symmetry of optical fiber which results in the additional polarization-based losses [22] it may leads difficulty in splicing, and become fragile in nature [23,24]. The numerically simulated results indicate that the incorporation of MFC in a SMF may improve the sensitivity compared to the previously reported articles
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