A Hydrogel Microneedle Patch for Point‐of‐Care Testing Based on Skin Interstitial Fluid

Skin interstitial fluid (ISF) holds great potential as a highly desirable sample resource for point-of-care testing (POCT), where the key is to effectively collect target biomarkers from ISF. Hydrogel microneedle patch has great promise for ISF extraction. However, it is challenging to recover target biomarkers from the extracted skin ISF in hydrogel microneedle patches in an easy-administrated, fast, and bulky instrument-free manner. Herein, a hydrogel microneedle patch made of polyvinyl alcohol (PVA) and chitosan (CS) for POCT based on the ISF is developed. The phase transition property of PVA/CS hydrogel makes the microneedles stiff when dry, which is beneficial to easily penetrate into skin. Meanwhile, the highly porous microstructure of hydrogel offers good swelling ability for extraction of ISF and the thermal degradation property of PVA makes it convenient to quickly and efficiently recover target biomarkers from microneedle patch. The capability of this platform for POCT applications is further demonstrated by successful detections of typical biomarkers collected from the mimetic skin and monitoring the glucose level in rabbit skins during a day. The developed hydrogel microneedle patch holds the advantages of extraction of skin ISF and recovery of biomarkers, thus presenting as a powerful platform for skin ISF-based POCT applications.