CdSe-ZnCdS quantum dot-assisted fiber-optic SPR sensor for body fat estimation: Impact of wide spectral range and temperature dynamic

Excess body fat is a significant factor in chronic diseases such as cardiovascular disease and type 2 diabetes, making an accurate and non-invasive measurement necessary. In this study, we present the first use of cadmium selenide-zinc cadmium sulfide (CdSe-ZnCdS) quantum dots in a fiber-optic surface plasmon resonance (SPR) sensor for measuring body fat. The sensor uses a germanium dioxide (GeO 2 ) core, sodium fluoride (NaF) cladding, an optimized silver layer, and a CdSe-ZnCdS quantum dot coating to improve sensitivity across a wide range of wavelengths and temperatures. We used wavelength interrogation to fine-tune both temperature and silver layer thickness. The sensor reached a maximum sensitivity of 3540 nm per refractive index unit (nm/RIU) and a figure of merit (FOM) of 33.7 RIU⁻¹ at 23°C, which is outperforming traditional Silver (Ag)-based sensors. Adding quantum dots led to better resonance shift and detection for human fat tissue, allowing for real-time and accurate body fat analysis. Moreover, fabrication process steps involving scalable chemical etching, silver deposition, and quantum dot coating are discussed for experimental feasibility. Our results show that adding quantum dots to fiber-optic SPR sensors is both new and effective for biomedical diagnostics. This progress helps create non-invasive tools for monitoring obesity-related health risks and supports personalized healthcare. Our results suggest that quantum dot-based optical sensors could be used in future clinical and wearable health monitoring devices. • CdSe-ZnCdS QD-assisted SPR sensor proposed for body fat estimation for the first time. • Demonstrates effect of wide spectral range and temperature dynamic on sensing. • Uses wavelength interrogation to analyze sensor performance. • Achieves 3540 nm/RIU sensitivity at 23 degree C max FOM of 33.7 /RIU.