Search

The opportunity to create magneto‐responsive soft materials (MSMs) with in‐process tailorable and locally controllable magnetic properties is highly desirable across many technological and biomedical applications. In this paper, this capability is demonstrated for the first time using computer‐controlled dual‐material aerosol jet printing (DMAJP) technology. This approach allows controlled variation of composition between the aerosols of a magnetic nanoparticles (MNPs) ink and a photocurable polymer during the printing process. The mixing ratio of the two aerosols determines the MNPs loading in the nanocomposite, which can be used to locally control the magnetic properties of the printed structures. The printing process is structured in a layer‐by‐layer fashion in combination with a sacrificial layer approach for building fully freestanding MSM structures that combine magnetoactive and non‐magnetoactive elements in a single process multi‐material printing method with no further assembly requirements. Using this method, the direct manufacturing of small‐scale multi‐material soft objects with complex shapes and programmable functions whose movements can be controlled by the application of an external magnetic field is demonstrated. [ABSTRACT FROM AUTHOR]

The field of soft robotics is rapidly progressing toward applications including; wearable electronics, prosthetics, and biomedical devices. This is leading to demand for flexible, embedded high‐performance strain sensors to deliver real‐time feedback on the static configurations and dynamic motions of these robotic devices, to ultimately enable the levels of autonomous control and structural monitoring required for intelligent manipulation. Herein, aerosol jet printing (AJP) technology is utilized to generate arbitrary piezoresistive strain sensor layouts on fibrous paper suitable for direct integration into elastomeric soft robots. A custom graphene nanoplatelet ink with a viscosity of around 2.70 cP has been formulated for optimized atomization and patterning of conductive traces via AJP. Single and multilayer printing onto different paper substrates are explored; with the nominal resistance of the printed tracks varying from 272 to 4900 kΩ depending on paper type and number of layers. Maximum gauge factors of 24.2 ± 1.8 and 56.5 ± 4.5 are determined for sensor surfaces under tensile and compression modes, respectively. To demonstrate the possibility for direct integration of this approach for soft robotics, strain sensors are directly printed onto the strain‐limiting layer of a pneumatic soft robotic gripper, to provide continuous feedback of the gripper over curvatures up to 80 m−1. [ABSTRACT FROM AUTHOR]

Supersonic cluster beam implantation of Ag nanoparticles is proposed for the fabrication of stretchable and compliant electrodes for dielectric elastomer actuators (DEAs) with reduced thickness. Thanks to the low-energy and finely tunable implantation process, a nanocomposite Ag/polydimethylsiloxane electrode layer is produced with a moderate stiffening effect for the DEA in contrast with a common deposition strategy for electrodes. Thin DEAs with an overall thickness of 17 μm were fabricated and tested under different preloading conditions, demonstrating a max uniaxial actuation strain of 2.5% at an actuation voltage of 765 V, lower than the typical voltage values of DEAs. The electrodes remained conductive up to 40% strain, and they fully recovered the original resistance after 70% stretching. Our results represent a significant step towards the development of DEAs operating at reduced actuation voltages, by stacking of micrometer-thick elastomer films, paving the way to novel applications in soft robotics. [ABSTRACT FROM AUTHOR]

Current technologies preclude effective and efficient self-assembly of heterogeneous arrangements of functional materials between 10 -1 and 10 -5 m. Consequently, their fabrication is dominated by methods of direct material manipulation, which struggle to meet the designers' demands regarding resolution, material freedom, production time, and cost. A two-step, computer-controlled is presented, multi-material self-assembly technique that allows heterogenous patterns of several centimeters with features down to 12.5 µm in size. First, a micro plasma jet selectively programs the surface energy of a polydimethylsiloxane substrate through localized chemical functionalization. Second, polar fluids containing functional materials are simplistically introduced which then self-assemble according to the patterned regions of high surface energy over timescales of the order of seconds. In-process control enables both high-resolution patterning and high throughput. This approach is demonstrated to produce heterogenous patterns of materials with varying conductive, magnetic, and mechanical properties. These include magneto-mechanical films and flexible electronic devices with unprecedented processing times and economy for high-resolution patterns. This self-assembly approach can disrupt the current lithography/direct write paradigm that dominates micro/meso-fabrication, enabling the next generation of devices across a broad range of fields via a flexible, industrially scalable, and environmentally friendly manufacturing route., (© 2024 The Author(s). Small published by Wiley‐VCH GmbH.)