Smart Textile: Functionalization and Electrohydrodynamic-Jet Printing of UiO-66-NH₂ Metal–Organic Frameworks for Gas-Sensing Applications

This study introduces a novel method for integrating UiO-66-NH₂ metal-organic frameworks (MOFs) into textiles using electrohydrodynamic jet (e-jet) printing to develop advanced sensors for nitric oxide (NO) gas detection. To enhance electrical conductivity and sensitivity, UiO-66-NH₂ MOFs were combined with the ionic liquid 1-ethyl-3-methylimidazolium trifluoromethanesulfonate. The resulting MOF-IL ink was precisely printed onto polylactic acid films, creating flexible and durable chemiresistive sensors. IL functionalization improved the MOF's conductivity by approximately 14× and enabled a significant and reversible response to NO gas, with a conductance change of 1634.67% compared to the negligible response of pristine sensors. Environmental influences, including humidity and temperature, were also characterized, confirming moisture-assisted proton transport and thermally activated conduction, with an activation energy of 114 meV. SEM, PXRD, EDX, and ATR-FTIR analyses validated the structural integrity, uniform deposition, and sensing mechanism. This work demonstrates the potential of e-jet printing for the scalable fabrication of MOF-based textile sensors for environmental monitoring and safety applications.