Next-generation microneedle patches for transdermal therapeutics and diagnostics.

Microneedle patches (MNPs) have emerged as versatile platforms for minimally invasive transdermal drug delivery, biosensing, and point-of-care diagnostics by transiently breaching the stratum corneum while minimizing pain and tissue damage. Recent advances in biomaterials, microfabrication, additive manufacturing, and bioelectronics have expanded MNP functionality beyond drug delivery to include controlled therapeutic release, interstitial fluid sampling, wearable biosensing, and closed-loop therapeutic systems. However, despite substantial technological progress, clinical translation remains constrained by challenges related to manufacturing scalability, device reproducibility, standardized characterization, quality assurance, regulatory approval, and commercialization. Unlike previous reviews that primarily emphasize microneedle classifications or material platforms, this review provides a critical translational perspective by integrating materials science, engineering, manufacturing, biosensing, and regulatory considerations into a unified framework. Major fabrication strategies, material platforms, and characterization methods are systematically compared with respect to mechanical performance, manufacturability, reproducibility, and clinical applicability. Current therapeutic and diagnostic applications are critically evaluated alongside the key barriers to industrial production and regulatory implementation. Emerging opportunities, including smart biosensing, stimuli-responsive materials, additive manufacturing, and closed-loop therapeutic systems, are also discussed. By highlighting the factors that govern technology readiness and clinical implementation, this review provides practical insights for accelerating the development and commercialization of next-generation microneedle platforms for drug delivery, biosensing, vaccination, and precision medicine.