Autonomous shape memory hinge for space applications powered via solar energy

This work demonstrates a proof-of-concept autonomous hinge for the deployment of satellite radiators. The hinge utilizes the shape memory effect (SME), thanks to the use of a shape memory alloy (SMA). First SMA wires based on Nickel-Titanium are embedded into an Ecoflex polymeric material and subsequently solidified. The bending of the hinge is induced by a thermal stimulus provided by a silver-based heater printed on a $10\mu m$ thick Polyether ether ketone (PEEK) substrate and embedded on top of the SMA structure. Heater powering is achieved via commercially available solar cells. Upon heating, the hinge transforms from a flat horizontal configuration to a curved bent one with approximately 45° bending angle on both sides of the hinge. In this work, we first describe the working principle of the hinge, to then show how the hinge is designed and prototyped, along with the realization of the proof-of-concept-device. Finally, laboratory testing of the autonomous hinge prototype is shown to investigate its motion and energy consumption performance. Upon reducing the temperature of the SMA wires by switching off the heater, the hinge returns to its original position with a 10° bending angle. The results prove that the hinge is capable of bending and unbending depending on the temperature, while being powered through solar cells using e.g., space solar radiation.