Hygrosensitive Dynamic Covalent Organic Framework Films: Harnessing Molecular Rotors for Moisture-Driven Actuation in Wearable Health Monitoring

Dynamic covalent organic frameworks (COFs) offer a promising platform for bioinspired soft actuators, yet transitioning their typical microcrystalline or single crystalline morphology to a flexible film suitable for wearable technology applications still remains a grand challenge. Herein, aiming at this issue, this work synthesizes an innovative class of hygrosensitive COF films, denoted as JNU-hygroCOF, with superior mechanical strength, chemical stability and tunable thickness from nanometer to micrometer scales through solution-processable sol-gel method. These JNU-hygroCOF films display exceptional moisture-driven actuation capabilities through modulating the intramolecular hydrogen bonds, which act as specific locks that open and close the molecular rotor of N & horbar;N bond responding to guest molecules, within the unique azine-pyridine molecular skeleton. By integrating these new JNU-hygroCOF films into a portable respiratory monitoring system, a proactive and preventive solution for diagnosing and managing respiratory disorders such as sleep apnea and asthma has been provided. This family of JNU-hygroCOF films display superior pore contraction/expansion dynamics and moisture-driven actuation ability through modulating the intramolecular hydrogen bonds, which act as specific locks that open and close the molecular rotor of N & horbar;N bond responding to guest molecules, within the unique azine-pyridine molecular skeleton, and exhibit high mechanical strength and chemical stability. image