A Beetle-Inspired Condensation Interface for Efficient Exhaled Breath Condensate Collection in an Externally Integrated Mask-Based Prototype

Abstract

Exhaled breath and exhaled breath condensate (EBC) contain physiologically relevant gaseous and ionic biomarkers and provide a noninvasive route for respiratory-state assessment. However, practical mask-based proof-of-concept readout remains limited by inefficient condensate harvesting and the lack of coordinated multichannel readout. Here, we present an externally integrated, beetle-inspired mask-based prototype that couples a heterogeneous-wettability condensation interface with time-aligned multichannel respiratory readout. The condensation interface consists of hydrophilic nucleation sites on micropillar tops and a superhydrophobic background on the pillar sidewalls and substrate, enabling preferential droplet nucleation and rapid droplet removal. Under matched test conditions, this biomimetic surface achieves a substantially higher EBC collection rate per unit area than smooth, nanocoated, and single-structure control surfaces while maintaining a stable advantage across variations in temperature, humidity, and inclination angle. An externally integrated acquisition module is further used to record real-time gas-phase CO2 and acetone signals together with a time-aligned condensate-derived EBC pH readout under a standardized workflow. The three-channel system shows good repeatability, acceptable environmental robustness, and long-term stability in bench-level evaluation. In a small pilot cohort, human monitoring further suggested state-associated temporal differences among resting, postprandial, post-exercise, febrile, and smoking-related conditions, although these observations should be interpreted as proof-of-concept evidence rather than subject-independent or clinically validated classification. This work establishes a proof-of-concept route that combines biomimetic EBC collection, multichannel respiratory readout, and temporal data fusion in a mask-based prototype.