Multiperformance Fully Physically Cross-Linked Organogel for All-Climate Wireless Human Motion Sensors and Water Writing Paper

Conductive organogels are considered ideal materials for the fabrication of flexible wearable electronic devices. However, the simultaneous realization of epidermal electronic devices with excellent self-healing, self-adhesion, multienvironment tolerance, and superior sensing performance remains a formidable challenge. In this study, a multiperformance conductive organogel was synthesized via a one-step photopolymerization of acrylic acid (AA) and acrylamide (AAm) in an H₂O/glycerol (Gly) solution comprising gelatin and Al³⁺ ions, utilizing zinc dimethacrylate (ZDMA) containing Zn²⁺-carboxyl coordination bonds as an ionic cross-linker. The physical cross-linked gelatin/P(AA-co-AAm-co-ZDMA)/Al³⁺ organogel was formed through the synergistic effects of multiple hydrogen bonding, dual ionic coordination bonds, and physical entanglement among diverse macromolecular chains. The prepared organogel exhibited superior toughness (387 kPa), significant self-healing ability (633% strain for the healed organogel), prominent moisture retention (weight retention of 80% after 15 days), and remarkable long-term temperature resistance. Without sealed packaging, the organogel maintained excellent mechanical properties even after exposure to different temperatures (−30 °C, 20 °C, and 50 °C) for durations of 15, 15, and 7 days, respectively. The strain sensor based on the gelatin/P(AA-co-AAm-co-ZDMA)/Al³⁺ organogel exhibited excellent sensitivity (gauge factor, GF = 3.36), outstanding signal stability (600 cycles at 60% strain), and precise monitoring of underwater motion. The wireless heart monitoring system integrated with the organogel sensor was affixed to the left chest of volunteers for real-time detection of minute human electrocardiograph (ECG) signals. More notably, the synthesized organogel exhibited a pronounced alteration in transmittance upon exposure to water and glycerol, rendering it suitable for application as a reusable water writing paper for recording and erasing information. The multifunctional organogel exhibits great promise for the development of future flexible electronics with enhanced environmental adaptability.