A Novel Optical Micro Ring Resonator Biosensor Design using Lithium Niobate on Insulator (LNOI) to Detect The Concentration of Glucose

Abstract

Sensing is not only essential but also unavoidable in the medical fields to analyze different types of biological samples for diagnostic purposes. Although, the conventional laboratory based sensing method provides high accuracy, sometimes, it is not suitable in terms of cost, sensing time, and amount of samples needed for sensing. In this work, we design a novel optical micro ring resonator biosensor utilizing the properties of lithium niobate (LiNbO3) on insulator (LNOI) to detect the concentration of glucose in blood and urine. Optical micro ring resonator attracts researchers in the biomedical field for their compactness, tenability, and low cost. Moreover, LNOI offers some special properties like favorable optical, mechanical, pieozoelectrical, photoelastic, photorefractive, and photovoltaic properties. First, various samples of devices were designed in COMSOL to perform the modal analysis. Then, these devices were implemented in Opti-FDTD to evaluate the performance of the sensor. By varying different parameters like rib height and width, we optimized the structure of the device where rib height, rib width, top layer width of LiNbO3, ring radius, and the distance between ring and waveguide are 0.56 µm, 0.5 µm, 0.16 µm, 15 µm, and approximately 70 to 80 nm, respectively. This optimized structure shows high quality (Q) factor, sharp resonance wavelength, and more distance between two resonance wavelengths of two different concentration of glucose. For sensing purpose, Gaussian modulated continuous wave of 1545 nm wavelength was used as input and best results in output were obtained at 1250 to 1280 nm wavelength.