Hydrophobic MOF/PDMS-Based QCM Sensors for VOCs Identification and Quantitative Detection in High-Humidity...

Area of Science:

• Materials Science
• Chemical Sensing
• Nanotechnology

Background:

• Metal-organic frameworks (MOFs) show promise for volatile organic compound (VOC) detection.
• MOF hydrophilicity hinders performance in humid environments, limiting practical applications.
• Developing robust sensors for humid conditions is crucial for accurate VOC monitoring.

Purpose of the Study:

• To create a stable and accurate VOC sensor array using a single quartz crystal microbalance (QCM) sensor.
• To enhance moisture resistance for reliable VOC detection in high-humidity environments.
• To achieve effective discrimination of various VOCs under diverse relative humidity (RH) conditions.

Main Methods:

• Fabrication of a QCM sensor with a composite adsorption layer of MIL-101(Cr) MOF and polydimethylsiloxane (PDMS).
• Implementation of a virtual sensor array (VSA) technique combining resonant signals and lumped parameters.
• Testing sensor performance across various RH levels (60% and 90%) and exposure durations.

Main Results:

• The PDMS layer significantly improved the sensor's moisture resistance.
• The sensor demonstrated stable performance over 2 days of water treatment.
• High sensitivity (2.68 mdB ppm^-1 for isopropanol) and low limit of detection (20.06 ppm for acetone) were achieved.
• Accurate discrimination (95.3%) of four VOCs was achieved under high RH conditions.

Conclusions:

• The proposed VSA QCM sensor offers a robust solution for reliable low-concentration VOC detection in humid environments.
• This technology is particularly promising for applications in challenging settings like underground spaces.
• The composite material approach effectively overcomes the limitations of MOF hydrophilicity in sensing applications.