A Hydrophilic Hollow Microneedle Platform for Sampling Interstitial Fluid and On-Site Biomarker Detection

Minimally invasive health monitoring is crucial for advancing personalized medicine, and microneedle-based platforms have emerged as a promising tool for collecting dermal interstitial fluid (ISF) in a pain-free and easy-to-use manner. ISF provides a rich source of biomarkers, potentially replacing traditional blood-based diagnostics. In this study, a superhydrophilic hollow microneedle patch capable of continuous ISF extraction and on-patch biomarker detection is presented. Utilizing high-precision projection micro-stereolithography, biocompatible, polymeric multichannel hollow microneedles (HMN) with tip diameters of 5-10 mu m, demonstrating excellent mechanical performance under compressive, shear, and penetration forces is fabricated. Wettability of HMN is dramatically enhanced by depositing a thin silicon oxide layer, which accelerates ISF extraction and enables prolonged and effective sampling. In vitro and ex vivo ISF extraction experiments are performed to investigate the effect of hydrophilicity, microchannel count, and microneedle height on liquid uptake. By integrating urea and pH colorimetric assays into the microneedle platform, direct, quantitative analysis of biomarkers from the sampled liquid is achieved. This all-in-one platform, combining superhydrophilic 3D-printed hollow microneedles and colorimetric sensing capabilities, represents a significant advancement toward the design and production of continuous, minimally invasive health monitoring devices.