Flexible, Integrated‐Porous Microneedle Sensor for Biofluid Sampling and On‐Site Biomarker Detection

ABSTRACT The rising prevalence of chronic diseases has driven rapid advances in wearable biosensing technology, which demands next‐generation devices capable of conveniently, rapidly, and accurately monitoring the health status of patients. Porous microneedles have garnered attention for their minimally invasive ability to extract interstitial fluid biomarkers and enable on‐site biomarker detection. However, their fluid absorption capacity remains limited due to a trade‐off between strength and porosity. In this study, we present an integrated‐porous microneedle sensor for biofluid extraction and on‐site biomarker detection. Owing to the nonsolvent‐induced phase separation (NIPS) method, the fabricated polyglycolic acid (PGA) microneedles show gradient porous structures, providing both high strength and absorption capacity of microneedles. By optimizing PGA concentration and integrating hydrophilic paper into MAP substrate, a single patch achieves an absorption capacity of 9.3 µL within 1 min by capillary action. Its extraction rate is 1.4 times that of PGA‐only MAPs developed in our earlier work. An optimized colorimetric paper sensor is also developed, with an image processing algorithm, which achieves a low limit of detection of 0.09 m m and high sensing linearity for cholesterol. The integrated‐microneedle sensor demonstrates effective detection of cholesterol (0.37–2 m m ), glucose (0.22–15 m m ), and both biomarkers onsite, highlighting their potential for wearable and disposable point‐of‐care biosensing.