A dual-diamond-ring photonic crystal fiber (PCF)-based sensor is proposed and analyzed herein for the detection of the concentration of alcohol in aqueous solution. Commercially available finite element method (FEM)-based simulation software (COMSOL Multiphysics® version 4.3b) is utilized to conduct a rigorous numerical investigation. The sample is injected inside the fiber. Several crucial optical parameters such as the index difference, coupling length, transmission spectrum, peak wavelength shift, and sensitivity are studied while ensuring an anisotropic perfectly matched layer (A-PML) for X and Y polarization, respectively. The results indicate that the coupling length strongly depends on the concentration of the solution. Moreover, maximum sensitivities for the X and Y polarization of 6166 nm/RIU and 6000 nm/RIU, respectively, are found from the computational model. Based on this outstanding performance, it can be anticipated that practical implementation of such sensors would open a new horizon in the area of biomedical or clinical sensing.