Bio-inspired microneedles with hierarchical microchannels for rapid interstitial fluid collection and analysis

The rapid and efficient detection of biomarkers in interstitial fluid (ISF) represents a compelling alternative to traditional invasive blood sampling for diagnostic and monitoring purposes. Here, bio-inspired microneedles (MNs) with hierarchical microchannels (HMC-MNs), emulating the liquid transport properties of <i>Sarracenia</i> trichomes, are presented. These MNs are fabricated using a secondary mold replication technique, ensuring cost-effectiveness and scalability. The HMC-MNs leverage capillary action to enhance ISF extraction, as validated through <i>ex vivo</i> and <i>in vivo</i> experiments demonstrating their robust ISF extraction capability. Integrated with a microneedle-based ISF sensing system (MISS), the platform enables real-time electrochemical and colorimetric detection of biomarkers, underscoring its potential for health monitoring and point-of-care applications. Furthermore, the collected ISF supports detailed off-needle analyses, expanding its diagnostic utility. By combining minimal invasiveness, rapid ISF collection, and versatile sensing capabilities, the HMC-MN system marks a significant step forward in wearable diagnostics, offering promising applications in both clinical and personal health management.