Fabry-Pérot Interferometer Hydrogel-Based Sensor for Continuous pH Monitoring in Diabetic Foot Ulcers

Diabetic foot ulcers (DFUs) are considered a severe complication of diabetes, often leading to chronic wounds, infections, and, in extreme cases, amputations. Continuous monitoring of the wound microenvironment, particularly pH balance variations, is critical for assessing ulcer progression and infection risk. In this study, a Fabry-Pérot Interferometer (FPI) hydrogel-based optical sensor was developed to enable real-time, non-invasive pH sensing by leveraging the pH-responsive expansion of a hydrogel within an optical microcavity. The sensor was tested in pH buffer solutions ranging from 3 to 8, mimicking the physiological pH conditions typically found in DFUs. Experimental results demonstrated a systematic wavelength shift in the interference spectrum, directly correlating with hydrogel expansion in response to increasing pH. The novel sensor exhibited high sensitivity, with a wavelength shift of 3.56 ± 0.299 nm per pH unit, as well as a strong linear correlation (R² = 0.9726, Pearson's r = 0.9862), confirming its accuracy and reproducibility in detecting pH variations. Microscopic imaging further validated the successful deposition, retention, and stability of the hydrogel inside the FPI cavity throughout pH testing. These findings establish the FPI-hydrogel sensor as a promising candidate for continuous pH monitoring in DFU management, offering a highly sensitive and reliable approach for early infection detection.Clinical Relevance- This study presents a novel highly sensitive and accurate FPI hydrogel-based sensor for continuous, non-invasive pH monitoring of the diabetic foot. Monitoring pH, a critical biomarker for DFUs, provides valuable insights into infection status and healing progression. Integration of this sensor into wearable devices for real-time wound monitoring enables the early detection of potential complications, facilitating timely interventions and improving clinical patient outcomes. This solution has the potential to revolutionize the management of diabetic ulcers, significantly reducing the risk of severe complications, including infections and amputations.