Co-authors​ :

 Somashree MONDAL (SWITZERLAND), Paweł ORKISZ , Bogdan SAPIŃSKI , Thomas GRAULE , Ralph SPOLENAK , Frank CLEMENS  

Magnetoactive soft elastomers (MSEs) have gained increased attention over recent years owing to their compliant mechanisms and adaptability to magnetic fields. Some particular applications where they are predominantly used are damping systems, soft robots with locomotion and shape-morphing capabilities and biomedical devices such as minimally invasive surgery tools and scaffolds. Magnetic particles play a key role in the properties of magnetoactive soft elastomers through their interaction with the applied magnetic field. Although numerous works have focused on MSEs comprising ferromagnetic particles, little attention has been given to ferrimagnetic particles. In this study, we have developed MSEs based on thermoplastic elastomer as the polymeric matrix and carbonyl iron or manganese ferrite as ferromagnetic and ferrimagnetic fillers, respectively. Using material extrusion-based additive manufacturing (MEX-AM), magnetoactive soft membrane structures have been fabricated to investigate the shape-morphing behavior of the magnetic composites. The magneto-mechanical properties of these membranes were measured using a custom-built control-test setup without applying a pre-strain or pre-load which is usually a prerequisite in conventional characterization methods. With the test setup a magnetic field in the form of a step-response and square wave was applied to the magnetic structure utilizing an electromagnet and the deformation was measured using a laser distance sensor. It was observed that at low magnetic fields both ferromagnetic and ferrimagnetic structures demonstrate similar magnetoactive performance, however, with an increase in magnetic field strength the ferromagnetic structure shows up to five times higher magnetoactive behavior. Furthermore, the effect of temperature on the magnetoactive performance of both composites was investigated. The heating of an electromagnet due to longer run time and high voltage to achieve a high magnetic field is a common phenomenon. In this work, we exploited this phenomenon to perform the temperature investigation. A higher temperature increase due to the heat dissipated from the electromagnet is observed in the structure with manganese ferrite particles leading to a substantial drift in its magnetoactive deformation. With the aid of the custom test setup, it is feasible to study the effect of various parameters such as magnetic field, and temperature on the magnetoactive behavior of these composites. This shall expand the existing choice of magnetoactive soft elastomers for various applications.