Integration and compensation of double SAW sensors with PEI@Mg-MOF-74 and GO/CMC film coated for CO2 leak monitoring in carbon capture utilization and storage

Carbon capture utilization and storage for reducing anthropogenic CO 2 emissions involve capturing CO 2 from industrial sources and injecting it into geological sinks such as oil reservoirs and depleted gas fields. To ensure environmental and public safety during carbon sequestration implementation, efficient CO 2 monitoring technologies must be developed to detect potential leaks at sequestration sites. Traditional CO 2 sensors used for monitoring these sites typically feature high costs and require specialized personnel for maintenance. This paper innovatively employs an immersion method to construct a surface acoustic wave (SAW) CO 2 sensor based on a polyethyleneimine-coated magnesium metal-organic framework (PEI@Mg-MOF-74) nanocomposite film. The PEI@Mg-MOF-74 SAW sensor exhibits ultra-high sensitivity across a CO 2 concentration range of 500–6000 ppm, with rapid response and recovery times of 11 s/6 s. Additionally, the sensor demonstrates excellent repeatability, selectivity, and long-term stability. Simultaneously, a graphene oxide/ Carboxymethyl Cellulose surface acoustic wave (SAW) humidity sensor was developed to address humidity-related issues. It exhibits ultra-high sensitivity of 14.29 kHz/% RH across a relative humidity range of 11–97% RH, coupled with rapid response and recovery times of 4 s/5 s. The SAW-based CO 2 sensor incorporates humidity compensation through the CSA-AdamW-CapsNet algorithm, and a wireless testing system based on the microcontroller was developed to enable wireless CO 2 and relative humidity measurement. This research provides theoretical foundations and technical prototypes for developing next-generation passive wireless smart sensing systems, holding significant application value in fields such as carbon dioxide capture and sequestration.