Surrogate‐Optimized Flow‐Guided Miniature Condenser for Rapid Exhaled Glucose Detection

ABSTRACT Human exhaled breath condensate (EBC) contains many health‐related metabolites and offers a route to non‐invasive disease monitoring. However, point‐of‐care EBC diagnostics remain limited by slow condensate collection. Existing open‐air condensers typically operate at condensation rates below tens of microliters per minute, requiring collection times of 10–20 min to obtain sufficient EBC volumes for measuring dilute biomarkers such as glucose, far exceeding the clinical requirement of 5 min. Here, it is shown that the EBC condensation rate is not limited by condensation heat transfer, but by vapor mass transport. As a result, conventional heat‐transfer‐based enhancement strategies provide limited benefit for breath condensation. Recognizing EBC collection as a mass transfer‐limited condensation process, a compact condenser is designed to maximize vapor access and EBC condensation within a 4 cm 4 cm footprint. A surrogate‐based optimization framework identifies high performance macrostructures that enhance vapor transport and condensation rate. The macrostructures are further refined through controlled wettability and nanoscale surface features to promote droplet removal and condensation rate. The resulting condenser achieves a sevenfold increase in condensation rate, raising collection rates to several hundred microliters per minute and enabling exhaled glucose analysis within 5 min.