Automated dip-coating surface modification system for microneedle sensors

Microneedle (MN)-based electrochemical sensors enable minimally invasive, real-time monitoring of interstitial fluid biomarkers. While tremendous attention has been given to the fabrication of MNs, little attention has been given to the critical surface functionalization of the MN electrode transducers. Current modification methods often suffer from poor reproducibility and excessive consumption of costly reagents. In this study, we introduce an automated dip-coating system designed for scalable, rapid, and reproducible functionalization of MN electrode transducers with different bioreceptors. Such an automated system, in combination with the 3D-printed electrochemical cell (EC cell) and the low-volume aptamer deposition chamber, leads to scalable surface modification, highly reproducible MN sensors, dramatic reduction in the costs of expensive biorecognition materials, and a highly reliable analytical performance toward diverse wearable sensing applications. Such integration of automation eliminates common errors associated with common drop casting and manual incubations, paving the way for advanced, scalable, and large-scale manufacturing of MN-based electrochemical biosensors.