Abstract

Carbon dioxide (CO₂) emitted by the skin during loading is a potential biomarker for the early detection of pressure ulcers (PUs). In this work, a reflection mode optical fibre CO₂ sensor (OFCS) was developed for early prediction of PUs formation. The optical fibre tip was coated with thymol blue using a sol‒gel coating process. The highest absorption peak of the OFCS was achieved at a wavelength of approximately 600 nm. The OFCS had response and recovery times of 60 seconds and 413 seconds, respectively, in the range of 0 ppm (0% CO₂) to 50000 ppm (5% CO₂). The sensor was tested on ten healthy volunteers measuring CO2 emitted from the skin during weight loading to mimic conditions that could lead to tissue breakdown. The CO₂ concentration increased during tissue loading indicating local tissue ischemia, a precursor to pressure ulcer formation.

© 2023 The Author(s)