A novel, low-cost, high performance dissolved methane sensor for aqueous environments

A new method for in-situ detection and measurement of
dissolved methane in aqueous media/environments with a limit of detection
of 0.2 nM (3σ, and t90~110s) and range (1-300 nM) is presented. The
detection method is based on refractive index (RI) modulation of a modified
PolyDiMethylSiloxane (PDMS) layer incorporating molecules of
cryptophane-A [1] which have a selective and reversible affinity for
methane [2]. The refractive index is accurately determined using surface
plasmon resonance (SPR) [3]. A prototype sensor has been repeatedly
tested, using a dissolved gas calibration system under a range of temperature
and salinity regimes. Laboratory-based results show that the technique is
specific, sensitive, and reversible. The method is suitable for miniaturization
and incorporation into in situ sensor technology.