Polyurethane packed graphene-coated spider silk by dip-casting for a highly stretchable strain sensor.

In recent years, naturally occurring materials have gained tremendous attention for their potential in the fabrication of advanced wearable electronic devices. Among these materials, spider silk is well-known for its outstanding mechanical strength and physical properties. Leveraging these attributes, a highly stretchable strain sensor was developed in this work utilizing polyurethane packed graphene-coated spider silk fabricated through a simple dip-casting method. The proposed sensor demonstrated remarkable mechanical strength, excellent sensitivity to strain and impressive recovery properties, attributed to the self-healing abilities of the polyurethane packaging. Additionally, polyurethane served as a protective layer, safeguarding the sensor from external environmental parameters and improving the lifetime of the device. The fabricated devices retained their performance parameters and other properties at up to 40% stretchability. FE-SEM and EDS elemental mapping were used to confirm the morphological properties and the homogenous coating of graphene on the spider silk fibers. The sensors were then attached to different parts of the human body to monitor pulse-rate, joint angles and posture, demonstrating outstanding results. This work paves the way for the design and fabrication of future wearable sensors using naturally occurring materials for advanced electronic applications.