Abstract
Ring resonators are well-known optical biosensors thanks to their relatively high Q-factor and sensitivity, in addition to their potential to be fabricated in large arrays with a small footprint. Here, we investigated the characteristics of a polymer ring resonator with a partially tapered waveguide for Biomedical Sensing. The goal is to develop a more sensitive biosensor with an improved figure of merit. The concept is more significant field interaction with the sample under test in tapered segments. Waveguide width is hereby gradually reduced to half. Sensitivity improves from 84.6 to 101.74 [nm/RIU] in a relatively small Q-factor reduction from 4.60 × 103 for a strip waveguide to 4.36 × 103 for a π/4 partially tapered one. After the study, the number of tapered parts from zero to fifteen, the obtained figure of merit improves from 497 for a strip ring to 565 for a π/4 tapered ring close to six tapered ones. Considering the fabrication process, the three-tapered one is suggested. The all-polymer material device provides advantages of a low-cost, disposable biosensor with roll-to-roll fabrication compatibility. This design can also be applied on silicon on isolator, or polymer on silicon-based devices, thereby taking advantage of a higher Q-factor and greater sensitivity.
Highlights
Accepted: 19 July 2021The rapidly increasing demand for precise, fast, compact, and low-cost sensors for healthcare [1], environmental monitoring, and food quality control is attracting substantial interest in optical-based [2] biosensors
This paper aims to introduce a novel ring resonator design that brings higher sensitivity with relatively small Q-factor reduction, which results in Figure of Merit (FOM) improvement, increasing field fraction toward cladding regions where biomarkers of interest exist
The introduced design principle is based on more significant field interaction with the sample under test by partially tapering the ring waveguide
Summary
The rapidly increasing demand for precise, fast, compact, and low-cost sensors for healthcare [1], environmental monitoring, and food quality control is attracting substantial interest in optical-based [2] biosensors. Thanks to their relatively high Q-factor and small size, optical microring resonators have long been the subject of research [3,4]. The evanescent field’s interaction with the propagated mode in the surrounding media is the sensing principle of these sensors. There is a need for more interaction between the sample under investigation and the evanescent field. There is a tradeoff with the Q-factor of the ring
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