Advancements in Electrohydrodynamic Jet Printing of Ionic Liquid-Functionalized Metal-Organic Frameworks for Wearable Nitric Oxide Sensors

Abstract

Electrohydrodynamic (E-jet) printing has emerged as a versatile method for depositing functional materials on flexible substrates, enabling the creation of advanced wearable sensors. This review explores the integration of ionic liquid (IL)-functionalized Cu3(HHTP)2 metal-organic frameworks (MOFs) via E-jet printing on electrospun polylactic acid (PLA) textiles, as pioneered by Ahmadipour et al. (2025). The approach achieves remarkable conductivity (19.23 µS·cm−1) and sensitivity (570% response at 100 ppm NO), surpassing traditional MOF-based sensors by facilitating mixed ionic-electronic conduction. Drawing from 41 recent studies (2020-2025), we analyze material synthesis, printing parameters, and sensor performance, introducing novel comparisons of jetting voltages and standoff distances across substrates. Two original tables benchmark conductivity and limit of detection (LOD) metrics, while figures illustrate process-structure- property relationships and humidity effects. The novelty lies in proposing a hybrid E-jet model for multi-analyte detection, addressing gaps in scalability and humidity resilience. This work provides a comprehensive playbook for developing low-power, heaterless wearable NO sensors aligned with occupational safety standards, paving the way for broader adoption in environmental monitoring.