Skin‐Interfaced Deep‐Tissue Sensing Patch via Microneedle Waveguides

Abstract Continuous, real‐time monitoring of biomarkers associated with local regions of the body can enhance both temporal and dimensional accuracy of proactive treatment to acute syndromes for critical illnesses, especially peripheral artery diseases. Conventional health monitors often face grand challenges in leveraging deep‐tissue sensing capability with a safe and compatible biointerface. Optical‐based noninvasive monitors may lack the ability to detect oximetry under subcutaneous fatty tissue due to the light scattering and absorption; implantables offer targeted sensing at depth, but may induce infection and inflammation. This report puts forward a wireless, wearable deep‐tissue sensing patch by incorporating biocompatible microneedle waveguides at the sensing interface, to bypass the light extinction in epidermic and dermic tissue and enable the tracking of oximetry at muscular tissue. The sensing patch provides multiple physiological measurements at the sensing area, including tissue oximetry, pulse oximetry, heart pulsation, and respiratory activities with a wireless platform for uninterrupted data advertising and processing to enable real‐time diagnostic analysis. The mechanical and thermal characterizations of the sensing patch with the microneedle waveguides validate the durable and safe operation at the skin interface. In vivo study with animal models of hindlimb ischemia demonstrates the high sensitivity and timely response of the sensing patch as muscle tissue hypoxia emerges.