Grating assisted temperature insensitive micro-ring resonator biosensor

Abstract

A grating-assisted temperature-insensitive micro-ring resonator bio-sensor is reported using finite-difference time domain simulation method. In addition to choosing a negative thermo-optic coefficient material water to nullify temperature-induced wavelength shift, optimization of the opto-geometric parameters provided a precisely zero-temperature sensitivity state of the structure. The negative thermo-optic coefficient of water counterbalances the positive shift in resonance wavelength originating from Si waveguides. The grating structure delocalizes the core field into the analyte region, which enhances field matter interaction to offer high bulk refractive index (RI) and affinity sensing. The advantage of incorporating grating structure in the ring has been demonstrated by comparing the bulk RI sensitivity and affinity sensitivity with and without the grating structure. Without the circular grating array, the bulk RI sensitivity is 214 nm/RIU and the affinity sensitivity is 0.139 nm/nm. Using grating in the ring structure offers an improved bulk RI sensitivity of 525 nm/RIU and an adlayer sensitivity of 0.515 nm/nm. We calculated the system limit of detection of the structure as ∼2×10−6 RIU. The fabrication tolerance of geometrical parameters, in the form of 10% variation in hole radius and 5% variation in other widths of our sensor, reveals a nominal temperature sensitivity of ∼6 pm/◦C. Changing the cladding analyte from pure water to other aqueous solutions, e.g. urine samples, also has a small impact on temperature sensitivity. The present work is useful in RI-dependent monitoring of the constituents present in aqueous medium-based bio-analytes samples in a variable ambient temperature environment.

Optical Biosensor Based on Porous Silicon and Tamm Plasmon Polariton for Detection of CagA Antigen of <em>Helicobacter Pylori</em>

“…Among these available biosensing techniques, optical biosensors have the advantages of high sensitivity, good specificity, easy operation, fast response, portability, and compatibility with optoelectronic integration. To illustrate the advantages, optical biosensors based on waveguides [15], ring resonators [16], resonant microcavities [17], photonic crystals [18], optic fibers [19], Surface Plasmon Resonance (SPR) [20], Localized Surface Plasmon Resonance (LSPR) [21], and Surface Enhanced Raman Spectroscopy (SERS) [22], have been proposed as effective detectors of various kinds of bio species, such as and biomarkers, proteins, DNAs, virus, bacterium, and cells. On the other hand, from the material perspective of biosensing technology, porous silicon (PSi) is a versatile nanoscale material for biosensing applications.…”