Enhanced Detection of Copper and Zinc Heavy Metals in Water via MZI polymer-based Waveguide Optical Sensor

Abstract A waveguide optical sensor functions to detect analytes that is suited for specific applications. In this work, a Mach Zehnder Interferometer (MZI) polymer-based waveguide optical sensor was developed with the focus of detecting copper and zinc heavy metal analytes in water samples. Two main MZI designs are investigated namely symmetrical and asymmetrical structures. The sensor’s performance was analyzed by simulating a 1550nm wavelength through the two MZI designs via Ansys Lumerical 2023 simulation software. Important parameters such as core dimension width and height, gap lengths and sensing arm lengths were analytically varied to optimize sensitivity and detection limit (DL). Copper analyte was successfully detected with a high sensitivity of 5,900 nm/RIU and DL of 17 x 10 −7 RIU and zinc with sensitivity of 2,000 nm/RIU and DL of 50 x 10 −7 RIU, in which both are attributed to asymmetrical design. For symmetrical design, copper analyte was detected with a low sensitivity of 7.3 nm/RIU and DL of 1.37 x 10 −7 RIU while no zinc analyte was observed. The optical sensor shows exceptional detection capability which has huge potential for use in other applications as well.