High fidelity fibre-based physiological sensing deep in tissue

TL;DR

This paper introduces a flexible, miniaturized fibre-optic sensor capable of performing high-precision, real-time measurements of pH and oxygen levels deep within tissue, specifically in lung alveolar spaces.

Contribution

It presents a novel fibre-based sensing platform with high-density fluorophore deposition enabling multiplexed, minimally invasive in vivo measurements of physiological parameters.

Findings

Achieved fast, accurate pH and oxygen measurements in lung tissue.

Demonstrated inverse fluorescence shift response to pH changes.

Platform shows no photobleaching and immunity to power fluctuations.

Abstract

Physiological sensing deep in tissue, remains a clinical challenge. Here a flexible miniaturised sensing optrode providing a platform to perform minimally invasive in vivo in situ measurements is reported. Silica microspheres covalently coupled with a high density of ratiometrically configured fluorophores were deposited into etched pits on the distal end of a 150 micron diameter multicore optical fibre. With this platform, multiplexed photonic measurements of pH and oxygen concentration with high precision in the distal alveolar space of the lung is reported. We demonstrated the phenomenon that high-density deposition of carboxyfluorescein covalently coupled to silica microspheres shows an inverse shift in fluorescence in response to varying pH. This platform delivered fast and accurate measurements, near instantaneous response time, no photobleaching, immunity to power fluctuations and a flexible architecture for addition of multiple sensors.