Long Period Grating Mach–Zehnder Interferometer Based Immunosensor with Temperature and Bulk Refractive Index Compensation

Wu, Peizhou; Liu, Liangliang; Morgan, Stephen P.; Correia, Ricardo; Korposh, Serhiy

Abstract

A long period grating Mach–Zehnder interferometer (LPGMZI) that consists of two identical long period gratings (LPGs) in a single fibre was developed to measure immunoglobulin M (IgM). The measured spectrum has fringes due to the interference between the core mode and cladding mode. This immunosensor inherits the advantages of an LPG and has the potential to compensate for unwanted signal changes due to bulk refractive index (RI) and temperature fluctuations by analysing interference fringes and their envelope. The external RI was measured from 1.3384 to 1.3670 in two different cases: (i) only the connecting section between the two LPGs is immersed or (ii) the whole LPGMZI is immersed. The fringes shift with an external RI in both scenarios, whereas the envelope stays still in case (i) or shifts at the same rate as the fringes in case (ii). The LPGMZI was also characterised at different temperatures between 25 °C and 30 °C by placing the whole LPGMZI in a water bath. The fringes and envelope shift at the same rate with temperature. The LPGMZI platform was then used to create an IgM immunosensor. The connecting section between the two LPGs was functionalised with anti-IgM and immersed into solutions with IgM concentrations from 20 μg/mL to 320 μg/mL. The fringes shift with IgM concentration and the envelope remains static. The results from this work show that LPGMZI has the potential to compensate for the temperature and bulk RI fluctuations and perform as a portable biosensor platform.

Citation

Wu, P., Liu, L., Morgan, S. P., Correia, R., & Korposh, S. (2022). Long Period Grating Mach–Zehnder Interferometer Based Immunosensor with Temperature and Bulk Refractive Index Compensation. Biosensors, 12(12), Article 1099. https://doi.org/10.3390/bios12121099

• Journal Article Type: Article
• Acceptance Date: Nov 25, 2022
• Online Publication Date: Nov 30, 2022
• Publication Date: Dec 1, 2022
• Deposit Date: Mar 29, 2023
• Publicly Available Date: Apr 6, 2023
• Journal: Biosensors
• Electronic ISSN: 2079-6374
• Publisher: MDPI
• Peer Reviewed: Peer Reviewed
• Volume: 12
• Issue: 12
• Article Number: 1099
• DOI: https://doi.org/10.3390/bios12121099
• Keywords: Clinical Biochemistry; General Medicine; Analytical Chemistry; Biotechnology; Instrumentation; Biomedical Engineering; Engineering (miscellaneous)
• Public URL: https://nottingham-repository.worktribe.com/output/14322844