Origami inspired dual matrix intelligent shape memory polymer composite folds for deployable structures

It remains a challenge to develop an intelligent, programmable multifunctional material system capable of recovering shape, withstanding high loads, and detecting folding extent remotely for self-deployable structures used in aerospace, robotics, and medical devices. In this work, our objective is to develop intelligent shape memory polymer composite (iSMPC) folds embedded with reduced graphene oxide-coated self-sensing fabric. This will enable remote sensing of the fold state based on resistance changes and achieve higher strength and modulus. Firstly, we demonstrate the ability to sense the extent of folding and establish the relationship between piezoresistivity and fold state change by conducting cyclic compression analysis on folds with different gap sizes (6 mm, 9 mm, and 12 mm) at temperatures of 25 °C, 35 °C, and 45 °C. The iSMPC fold with a 6 mm gap exhibited the highest bending stiffness (650.3 N mm⁻¹) and curvature (0.55 mm⁻¹), resulting in a higher change in fractional change in resistance (FCR). Subsequently, the shape memory cycles of the 6 mm iSMPC fold were demonstrated through localized controlled heating. Its shape recovery process exhibited repeatable behavior with a high recovery ratio of 95%. Lastly, a two-fold iSMPC structure was developed, and its performance was analyzed during a complete shape memory cycle. The piezoresistive response during higher-temperature cyclic loading resembled that of the single fold, exhibiting an FCR range between −9% and 5%, thereby demonstrating the repeatability of the iSMPC fold response.