Dissolved methane sensing using a microchanneled hollow-core anti-resonant fiber

Deep-sea dissolved methane detection is significant for global climate research and ecological monitoring. Here, we report a dissolved methane sensor employing a hollow-core anti-resonant fiber (HC-ARF) that incorporates fifteen 300 × 45 μm microchannels fabricated using a femtosecond laser. To our knowledge, this is the first report of a dissolved gas sensor based on a microchanneled HC-ARF. The HC-ARF was enclosed in a gas-permeable, water-impermeable membrane tube, enabling efficient degassing and rapid gas exchange. Using wavelength-modulation tunable diode laser absorption spectroscopy at 1653 nm, the sensor detected CH₄ dissolved in water and achieved a 400 s response time. Calibration over 0.05%-2% CH₄ showed a linear response. We further demonstrated stable sensing performance in high-salinity solutions, confirming the sensor's capability for dissolved CH₄ detection in seawater environments.