Design and Feasibility Analysis of a Hybrid Membrane-Based Underwater Respiration System: Integrating TPMS Architectures with Exhaled Breath Recycling

The paper presents the AquaLung, a theoretical portable underwater respiration concept combining membrane-based dissolved-oxygen separation from seawater with exhaled-breath recycling. The system integrates 3D-printed polypropylene membranes incorporating triply periodic minimal surface (TPMS) architectures, alongside bio-inspired pore geometries. A quantitative oxygen mass-balance model is developed to examine the feasibility of meeting human respiratory demand, while proposed experimental phases address membrane performance, gas separation, CO₂ scrubbing, power requirements, environmental sensitivity, and safety. The concept is explicitly presented as a theoretical framework rather than a validated engineering solution.