Recent advances in the preparation of microneedle patches for interstitial fluid extraction and analysis

Interstitial fluid (ISF) fills the intercellular space and contains abundant biomarkers, which can serve as alternatives to conventional sources like blood and urine for disease surveillance and clinical diagnosis. However, conventional methods of sampling ISF often cause patient discomfort and lead to poor compliance. Microneedles (MNs) represent a novel technique that not only simplifies the sampling process but also enhances patient tolerance. The utilization of MNs for extracting ISF has emerged as a prominent area of research due to its simplicity, speed, reliability, and minimally invasive nature. This paper provides an overview of four commonly used types of MNs for ISF sampling and offers a detailed description of the preparation methods for MNs with different structures. Additionally, it outlines the applications and outcomes of using MNs as medical devices for clinical diagnosis and monitoring, and discusses the applications and advantages of MNs-electrochemical sensing technology for analyzing and detecting various biomarkers in ISF. Furthermore, the mechanisms involved in MNs-based ISF extraction are presented, followed by a discussion on the current advancements in industrial applications and future directions in this field.