The quest for highly sensitive QCM humidity sensors: the coating of CNT/MOF composite sensing films as case study
AuthorsChappanda, Karumbaiah. N.
Patole, Shashikant P.
Salama, Khaled N.
KAUST DepartmentComputer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division
Electrical Engineering Program
Advanced Membranes and Porous Materials Research Center
Functional Materials Design, Discovery and Development (FMD3)
Physical Sciences and Engineering (PSE) Division
KAUST Grant NumberFCC/1/1972-05-01
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AbstractThe application of metal-organic frameworks (MOFs) as a sensing layer has been attracting great interest over the last decade, due to their uniform properties in terms of high porosity and tunability, which provides a large surface area and/or centers for trapping/binding a targeted analyte. Here we report the fabrication of a highly sensitive humidity sensor that is based on composite thin films of HKUST-1 MOF and carbon nanotubes (CNT). The composite sensing films were fabricated by spin coating technique on a quartz-crystal microbalance (QCM) and a comparison of their shift in resonance frequencies to adsorbed water vapor (5 to 75% relative humidity) is presented. Through optimization of the CNT and HKUST-1 composition, we could demonstrate a 230% increase in sensitivity compared to plain HKUST-1 film. The optimized CNT-HKUST-1 composite thin films are stable, reliable, and have an average sensitivity of about 2.5×10−5 (Δf/f) per percent of relative humidity, which is up to ten times better than previously reported QCM-based humidity sensors. The approach presented here is facile and paves a promising path towards enhancing the sensitivity of MOF-based sensors.
CitationChappanda KN, Shekhah O, Yassine O, Patole SP, Eddaoudi M, et al. (2017) The quest for highly sensitive QCM humidity sensors: the coating of CNT/MOF composite sensing films as case study. Sensors and Actuators B: Chemical. Available: http://dx.doi.org/10.1016/j.snb.2017.10.189.
SponsorsThis work was partially sponsored by the Advanced Membranes and Porous Materials Center (AMPMC)’s grant FCC/1/1972-05-01 within the “Stimuli Responsive Materials” thrust. We thank Ulrich Buttner of ‘Microfluidic Lab, part of the Nanofabrication Core Lab’, for providing his assistance in the project.