A photoprogrammable electronic nose with switchable selectivity for VOCs using MOF films

Area of Science:

• Materials Science
• Chemical Sensing
• Nanotechnology

Background:

• Advanced analytical applications demand adaptable smart materials and sensor systems.
• Reversible photochemistry in nanoporous materials offers a pathway for tunable sensor selectivity.
• Photoresponsive materials enable dynamic configuration of sensor arrays for specific tasks.

Purpose of the Study:

• To develop a sensor array with light-controlled selectivity for molecular sensing.
• To investigate the use of photoresponsive metal-organic frameworks (MOFs) in an electronic nose (e-nose).
• To demonstrate the potential of optically configurable materials for intelligent molecular sensing.

Main Methods:

• Fabrication of an e-nose using MOFs functionalized with photoresponsive fluorinated azobenzene groups.
• Modulation of the azobenzene trans-cis isomer ratio using light irradiation to define sensor states.
• Gravimetric monitoring of molecular uptake using a four-channel quartz-crystal microbalance (QCM) and analysis with machine-learning algorithms.

Main Results:

• The sensor array's selectivity was reversibly controlled by light irradiation, altering VOC affinity.
• Programming the e-nose with different light colors enhanced selectivity and reduced cross-sensitivity.
• The photoprogrammed e-nose achieved perfect identification of tested volatile organic compounds (VOCs).

Conclusions:

• Photoswitchable MOFs offer a promising platform for developing optically configurable e-noses.
• This approach enables intelligent molecular sensing with tunable selectivity.
• The concept is applicable to various sensing materials and photoswitches beyond azobenzene-MOFs.