SERS-Integrated Microneedles: Bridging Nanoplasmonics and Microsampling for Advanced Bioanalysis.

Sensitive analytical techniques capable of in situ measurements in biological tissues with high selectivity and rapid response are essential for health monitoring, disease diagnosis, agriculture management, and food safety. However, conventional biological sampling is often invasive, expensive, and inconvenient. Microneedle (MN) technology offers a noninvasive, quick, and self-administered approach for in vivo sampling of extracellular fluids that are rich in biomarkers and metabolites indicative of health status. By integrating MNs with highly sensitive surface-enhanced Raman spectroscopy (SERS), the hybrid technique provides unprecedented convenience, user compliance, and analytical sensitivity for biomonitoring. The versatility of SERS-integrated MNs (SERS-MNs), along with their integration into portable, self-administered devices, makes them ideal for point-of-care testing. SERS-MNs can also be incorporated into wearable medical devices for real-time, long-term biochemical monitoring with high temporal resolution. This perspective explores the emerging applications of SERS-MNs by critically examining the key requirements in materials, structural design, and fabrication methods, while elucidating their underlying working principles. We further assess current challenges and highlight future opportunities, providing insights to advance their use in clinical diagnostics, precision agriculture, and food safety. This work offers a systematic discussion on the integration of SERS-MNs into wearable devices for long-term, real-time health monitoring, opening new possibilities to empower individuals in proactive health management.