Spatially Configurable Conformal Sensor Integration on an Ultra‐Fine Metallic Needle for Minimally Invasive Deep‐Tissue Oxygen Monitoring

Precise, real‐time biochemical measurement within deep biological tissue remains limited by the challenge of integrating mechanically robust sensing architectures into minimally invasive needle platforms. Here, we report a multi‐point oxygen‐sensing ultra‐fine clinical needle (MO‐UFN, 30‐gauge, approximately 0.3 mm in diameter), fabricated by conformally integrating a microscale flexible thin‐film electrochemical oxygen sensor array onto a clinical needle. The device provides lithographically defined sensing and insulating regions along the needle surface while preserving the ultra‐small needle diameter. Five‐site oxygen sensing was demonstrated through electrochemical characterization in solution and time‐resolved measurement in a hypoxia‐mimicking hydrogel phantom. Ex vivo insertion testing and short‐term in vitro cytocompatibility assessment further supported the mechanical and biological feasibility of the platform under the tested conditions. This work establishes a spatially configurable needle‐based sensing architecture for minimally invasive biochemical monitoring in heterogeneous deep‐tissue environments.