4D printing concepts are related to the capability of a 3D printed objects to change its shape or functionality in response of an external stimulus or a combination of external stimuli. This concept takes advantage of the ability of a material to change a set of its intrinsic properties as function of the external environment like for example heat, moisture, pH, light and mechanical loading. However, for specific application like space the external stimulus that can be used from the environment are limited and/or cannot be well controlled. In this respect, 4D printing concepts using electrically driven stimuli will be an asset making then independent from the environment. Among the wide range of material used for 4D printing applications, thermoplastics have shown great interest especially due the ease of processing, shape memory capabilities and ability to be functionalised and blended. Advanced in electrically conductive thermoplastics is opening new capabilities for 4D printing where one could use joule effect to generate on demand and locally heat that will trigger the shape deformation.

In this work, we are using the Fused Filament Fabrication (FFF) process known as 3D printing of two different thermoplastics with one being electrically conductive to design and produce objects (i.e mechanism) with reversible shape changing capability using electrical current as stimulus. The results obtained during this study will be presented at first, focussing on material assessment with on one hand, the most suitable shape memory thermoplastic and on the other hand the most suitable electrically conductive material considering thermal performance, processing windows, electrical performance toward joule effect (Fig 1) and adhesion between each other. Then the design, production using a combination of polyurethane based shape memory Polymer and a biopolymer blended with CNTs and testing of demonstrator with bending, torsion and reversible deployment capabilities will be exposed.