3D Printing-Based Modular Disposable Flexible Microneedle Sensor: Development and Continuous Monitoring Performance Validation

Interstitial fluid (ISF) contains biomarker concentrations that closely correlate with those in plasma, making it a highly suitable medium for continuous physiological monitoring systems. To address the demand for multi-analyte adaptability in continuous monitoring applications, a modular, disposable, flexible microneedle-based sensing system is developed in this study. The proposed system is fully constructed using 3D-printed structural components, enabling a simplified fabrication process and cost-effective manufacturing. Modularity is achieved through the replacement of specific biorecognition layers, allowing potential adaptation for the detection of different biomarkers. The overall system architecture and key fabrication procedures of the microneedle electrode are systematically presented. Glucose (GLU) in ISF is selected as a model analyte for proof-of-concept validation. By integrating an auxiliary insertion mechanism and a signal acquisition module, continuous glucose monitoring is successfully demonstrated. The sensor exhibits a linear response over a concentration range of 2.2–27.8 mM, with a limit of detection (LOD) of 0.26 mM (S/N = 3), covering the physiological glucose concentration range in humans. In addition, the system demonstrates fast response characteristics and high sensitivity, while maintaining stable performance under moderate temperature variations. It is noted that the current experimental validation is limited to glucose detection, whereas sensing capabilities for other biomarkers such as lactate and uric acid remain at the level of platform design and potential methodological extension, and require further systematic verification. Overall, the proposed modular design strategy provides a flexible and scalable technical framework for dynamic continuous monitoring of multiple biomarkers in physiological environments.