Response mechanism and experimental research of in-situ methane sensors based on semi-permeable membrane technology

Methane plays a crucial role in deep-sea cold seeps, hydrothermal ecosystems, Earth's carbon cycle, atmospheric greenhouse effects, and the formation of hydrates. In-situ methane sensors can provide real-time online monitoring of methane concentrations in deep-sea environments. The response time of these sensors is a critical parameter for evaluating their real-time performance. Based on the structure of a self-developed membrane degassing in-situ methane sensor, a gas-liquid dynamic equilibrium response model was established using gas diffusion and dual-membrane exchange theories. The study found that the response equation for deep-sea in-situ methane sensors follows a natural logarithm function. The response time improves with larger membrane areas and smaller internal flow field volumes. Experimental evaluation of the sensor's response performance showed results consistent with the theoretical model, with a measured response time t_0.63 of 30 minutes. This provides valuable insights for structural optimization and performance enhancement of methane sensors.