Microneedle-Based\nElectrochemical Array Patch for\nUltra-Antifouling and Ultra-Anti-Interference Monitoring of Subcutaneous\nOxygen

Oxygen saturation is a crucial indicator\nin the management\nof various\ndiseases and in preoperative diagnosis, and the detection of oxygen\ncontent is valuable in guiding clinical treatment. However, as the\nclassical and dominant oxygen detection strategies, current photoelectric\noximeters and electrochemical-based blood gas analyzers often suffer\nfrom significant interindividual variation and poor compliance, respectively.\nIn recent years, wearable microneedles (MNs) for analyzing biomarkers\nin interstitial fluid (ISF) have received great attention and recognition\nmainly for the reason that the content of the substances distributed\nin ISF has a better correlation with that in blood circulation compared\nwith other body fluids such as sweat and saliva. Herein, an MN-based\nelectrochemical array system was developed for continuous subcutaneous\noxygen sensing, in which gold-modified commercial acupuncture MNs\nwere used as the sensing units, and a tailored mini-workstation, a\nnonwoven fabric, and a water and air isolation membrane were integrated\nto fabricate a wearable array patch. Notably, a multifunctional swelling\nresin with good biocompatibility was adopted to decorate the MN surface\nas a protective layer and as an electrolyte gel. The swelling resin\nfeatured the ability to reduce epidermis secretions during the sensor\narray penetrating the skin and to decrease the interference of other\nbiomolecules in ISF for oxygen assay during measurement. This proposed\narray patch can perform the subcutaneous oxygen analysis in the physiological\nrange of 6–150 mmHg with high sensitivity (0.3817 μA/mmHg)\nand low theoretical limit of detection (5.06 mmHg). It also showed\ndecent stability and selectivity in the presence of several kinds\nof exogenous and endogenous substances. Finally, the patch accomplished\ncontinual monitoring of the subcutaneous oxygen content during long-term\nphysical exercise, showing great potential in providing warning about\nthe hypoxia status of the human body. It could be foreseen that this\nhigh-performance patch will play an active role in respiratory disease\nevaluation, surgical monitoring, and public health care.