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Physically soft magnetic materials (PSMMs) represent an emerging class of materials that can change shape or rheology in response to an external magnetic field. However, until now, no studies have investigated using an electropermanent magnet (EPM) and magnetic repulsion to magnetically deform PSMMs. Such capabilities would enable the ability to deform PSMMs without the need for continuous electrical input and produce PSMM film deformation without an air gap, as would be required with magnetic attraction. To address this, we introduce a PSMM-EPM architecture in which the shape of a soft deformable thin film is controlled by switching between bistable on/off states of the EPM circuit. We characterized the deflection of a PSMM thin film when placed at controlled distances normal to the surface of the EPM and compared its response for cases when the EPM is in the ‘on’ and ‘off’ states. This work is the first to demonstrate a magnetically repelled soft deformable thin film that achieves two electronically-controlled modes of deformation through the on and off states of an EPM. This work has the potential to advance the development of new magneto-responsive soft materials and systems.

 

Over the last decade, researchers have investigated the potential of nano and microfiber scaffolds to promote wound healing, tissue regeneration, and skin protection. The centrifugal spinning technique is favored over others due to its relatively straightforward mechanism for producing large quantities of fiber. Many polymeric materials have yet to be investigated in search of those with multifunctional properties that would make them attractive in tissue applications. This literature presents the fundamental process of fiber generation, and the effects of fabrication parameters (machine, solution) on the morphologies such as fiber diameter, distribution, alignment, porous features, and mechanical properties. Additionally, a brief discussion is presented on the underlying physics of beaded morphology and continuous fiber formation. Consequently, the study provides an overview of the current advancements in centrifugally spun polymeric fiber-based materials and their morphological features, performance, and characteristics for tissue engineering applications. 

Liquid crystal elastomers (LCEs) are becoming increasingly popular as a shape memory material for soft robot actuators that operate in a contractile or flexural mode. There have been previously studies on the use of LCEs for reversible changes in surface topography. However, surface protrusions have typically been limited to the order of 1 μm or depend on light, heat, or electrical stimulation that are difficult to locally control or require relatively high voltage. This article presents a novel operation mode of LCE actuators based on the wrinkling behavior of an LCE‐elastomer bilayer architecture. Embedding a liquid‐metal‐based conductive ink within the LCE enables electrical control of surface wrinkling through Joule heating. The actuator cells can generate wrinkles with amplitudes ranging from 17 to 45 μm within 30 s under an input power of 2 W and a voltage on the order of 1 V. As the bilayer is composed entirely of soft materials, it is highly deformable, flexible, and can be integrated into a multi‐cell array capable of bending on curved surfaces.

 

Soft, stretchable sensors, such as artificial skins or tactile sensors, are attractive for numerous soft robotic applications due to the low material compliance. Conductive polymers are a necessary component of many soft sensors, and this work presents the electromechanical characterization of 3D-printable conductive polymer composites. Dog-bone shaped samples were 3D printed using a digital light processing (DLP)-based 3D printer for characterization. The 3D printable resin consists of monomer, crosslinker, conductive nano-filler, and a photo-initiator. The characterization was performed in two tracks. First, the effect of two different crosslinkers was investigated with different compositions and second, the effect of concentration of conductive nano-fillers was explored. Crosslinkers were chosen by referring to previous studies, and carbon nanotubes (CNTs) were utilized as conductive nano-fillers. The samples were 3D printed and characterized using an electromechanical test setup. To demonstrate utility for 3D printed soft robotics, a capacitance-based joystick sensor composed of both conductive and non-conductive resins was 3D printed. 

Solution-processed graphene inks that use ethyl cellulose as a polymer stabilizer are blade-coated into large-area thin films. Following blade-coating, the graphene thin films are cured to pyrolyze the cellulosic polymer, leaving behind an sp 2 -rich amorphous carbon residue that serves as a binder in addition to facilitating charge transport between graphene flakes. Systematic charge transport measurements, including temperature-dependent Hall effect and non-contact microwave resonant cavity characterization, reveal that the resulting electrically percolating graphene thin films possess high mobility (≈160 cm 2 V −1 s −1 ), low energy gap, and thermally activated charge transport, which develop weak localization behavior at cryogenic temperatures. 

This work presents the design, modeling, and fabrication of a whisker-like sensor capable of measuring the whisker's angular displacement as well as the applied moments at the base of the whisker. The sensor takes advantage of readily accessible and low-cost 3D magnetic sensors to transduce whisker deflections, and a planar serpentine spring structure at the whisker base is used to provide a mechanical suspension for the whisker to rotate. The sensor prototype was characterized, calibrated, and compared with analytical models of the spring system and the magnetic field. The prototype showed a moment sensing range of 1.1N·mm when deflected up to 19.7°. The sensitivity of the sensor was 0.38°/LSB for the angular displacement sensing, and 0.021 Nmm/LSB for the moment sensing. A fully integrated system is demonstrated to display real-time information from the whisker on a graphical interface.