Fast Surface Acoustic Wave-Based Sensors to Investigate the Kinetics of Gas Uptake in Ultra-Microporous Frameworks

• DOI: 10.1021/acssensors.7b00014
• Publication Date: 2017-05-21T12:00:53Z
• Authors: Benjamin Paschke; Achim Wixforth; Dmytro Denysenko; Dirk Volkmer
• Keywords: Response time; Gaseous diffusion

Observation of the kinetics and measurement activation energies for gas diffusion in porous materials requires very fast sensitive sensors. In this work, thin films metal–organic frameworks (MOFs) with different pore sizes are grown on a surface acoustic wave (SAW) substrate, resulting specific sensor systems detection various gases at short time scales. Using specially designed SAW delay lines detection, up to 200-nm-wide cubic MOF crystals were directly from solution chip area. One example, MFU-4, exhibits smallest aperture 2.5 Å shows highly response CO2, H2, He, NH3, H2O. It is shown that such MOF@SAW responds within milliseconds loading its sensitivity reaches levels as low 1 ppmv, currently only limited by mixing system. This unique combination characteristics allows even real-time investigations sorption during uptake release. As typical sensors, production chips straightforward inexpensive and—combined properties MOFs their tunable adjustable internal properties—holds promise applications.