We develop point‑of‑care diagnostic platforms and non‑invasive breath‑analysis systems that combine photonics with chemical transduction. Architectures integrate electrochemical gas sensors, micro‑/nano‑systems, fluidics, and calibration models, with instrumentation for signal acquisition, processing, and representation. The goal is rapid, low‑cost screening and monitoring aligned with clinical workflows, enabling early detection and longitudinal assessment in decentralized settings