Lateral Flow-Based Skin Patch for Rapid Detection\nof Protein Biomarkers in Human Dermal Interstitial Fluid

Rapid diagnostic\ntests (RDTs) offer valuable diagnostic information\nin a quick, easy-to-use and low-cost format. While RDTs are one of\nthe most commonly used tools for in vitro diagnostic testing, they\nrequire the collection of a blood sample, which is painful, poses\nrisks of infection and can lead to complications. We introduce a blood-free\npoint-of-care diagnostic test for the rapid detection of protein biomarkers\nin dermal interstitial fluid (ISF). This device consists of a lateral\nflow immunochromatographic assay (LFIA) integrated within a microfluidic\nskin patch. ISF is collected from the skin using a microneedle array\nand vacuum-assisted extraction system integrated in the patch, and\ntransported through the lateral flow strip via surface tension. Using\nthis skin patch platform, we demonstrate in situ detection of anti-tetanus\ntoxoid IgG and SARS-CoV-2 neutralizing antibodies, which could be\naccurately detected in human ISF in <20 min. We envision that this\ndevice can be readily modified to detect other protein biomarkers\nin dermal ISF, making it a promising tool for rapid diagnostic testing.