A Magnetically Self-Aligning, Fast Full-Device Self-Healing, Skin-Attachable Liquid Metal Strain Sensor Based on Photothermal Polyurethane

There is a growing need for research on self-healing materials capable of spontaneously repairing physical damage, allowing the fabrication of highly durable wearable devices featuring flexibility and stretchability. Herein, the study reports on the fabrication of a novel, magnetically aligning, fully and rapidly self-healing skin-attachable biosensor based on newly synthesized photothermally self-healing polyurethane. By introducing photothermal amine-capped aniline trimers to selectively self-healable polyurethane, the synthesized self-healing polymer achieves a fast and high recovery rate of 81.1% from complete bisection upon laser irradiation for just 3 min. Additionally, a thin-film type strain sensor fabricated via the spray patterning of liquid metal EGaIn as an electrode onto the surface of the self-healing polymer exhibits a high sensitivity to strain from deformation, enabling the real-time monitoring of bio-signals. Furthermore, the integration of a magnetic aligning layer directly patterned and embedded onto the self-healing polymer enhances the self-healing performance of the sensor after damage by 4.3 times on average, compared to when using manual alignment. In short, this work demonstrates a high-performance fully self-healing electronic device via the synthesis of novel fast self-healing photothermal polymers and the introduction of patterned liquid metal electrodes and magnetic alignment layers.