Work

Thermal blood flowmeter based on cascaded Fabry-Pérot Interferometers utilising the enhanced harmonic Vernier effect

Year: 2025

Type: article

Abstract: • Innovative thermal blood flowmeter combining cascaded Fabry-Pérot Interferometer (CFPI) and multimode Fibre (MMF). • Enhanced harmonic Vernier effect improves temperature sensitivity, achieving 26.67±1.07 nm/°C, which is 117× higher than a single polymer cavity. • Cascaded CFPI structure enables to generate Vernier effect in a compact design, eliminating the need for a separate reference cavity. • Wide flow measurement range (20–300 ml/min) with temperature variation below 1 °C. Localised accurate blood flow measurement is crucial in various clinical scenarios for diagnosing and treating vascular conditions. An innovative thermal blood flowmeter that comprises cascaded Fabry-Pérot Interferometer (CFPI) and a multimode fibre (MMF) is presented. The MMF is connected to a green LED for modulating fluid temperature, and the resulting temperature change is inversely proportional to the flow rate. The CFPI consists of a polymer and air cavities of lengths 285.1 μ m and 408.4 μ m , respectively. The CFPI temperature sensitivity is enhanced due to the high thermo-expansion of the polymer compared to silica fibre. The typical discrete FPI system based on the Vernier effect comprises one sensing cavity and a reference cavity of constant length. In contrast, the CFPI is more compact and further enhances the sensor's sensitivity because the lengths of the two cavities change in opposite directions. The CFPI's temperature sensitivity is improved 117.4 times compared to a single polymer cavity and can reach 26.67 ± 1.07 nm/ °C. Flow in a phantom system can be measured over a range from 20 ml/min to 300 ml/min.

Source: Optics and Lasers in Engineering

DOI: 10.1016/j.optlaseng.2025.109145

Authors: Ruirong Gong, Stephen P. Morgan, Serhiy Korposh, Chenyang He, Barrie R. Hayes-Gill, Ricardo Correia

Institution: University of Nottingham

Language: English

Topic: Advanced Fiber Optic Sensors

Subfield: Electrical and Electronic Engineering

Field: Engineering

Domain: Physical Sciences

SDG: Good health and well-being

Open Access status: hybrid

Estimated APC paid: $4,020