Search for: All records

ABSTRACT While silver selenide (Ag₂Se) is considered a promisingn‐type thermoelectric material, the low throughput of conventional solid‐state processing for selenide‐based systems highlights the need for scalable solution‐based alternatives. However, most solution‐processing approaches require thermal annealing to form high‐quality films, whereas Ag₂Se exhibits limited thermal stability (<350°C), posing a nontrivial issue for processing. To address this, we systematically investigate the incorporation of a controlled dual dopant (Sb‐Se) into Ag₂Se through a compositionally tuned nano‐ink. Flexible Sb_xAgSe_0.5+yfilms were fabricated using the direct ink writing (DIW) approach, and the doped films demonstrated enhanced thermal stability. The effect of dopants on microstructure was further studied using neutron diffraction at the VULCAN instrument and elemental analysis using SEM‐EDS. Results demonstrated that elemental doping of Sb and Se leads to stable/enhanced Seebeck coefficients after thermal exposure, in contrast to undoped Ag₂Se films with decreased Seebeck due to thermal degradation, where the thermal behavior and possible degradation pathways are evaluated at 200, 400, and 600°C. A wearable thermoelectric generator (TEG) demonstrated a peak power density of ∼60 µW cm⁻²at 30°C temperature difference. Overall, this study suggests the possibility of printing‐based Ag₂Se thermoelectric devices with high‐temperature processability for waste‐heat harvesting and harsh electronic applications. 

Abstract Recent advancements in additive manufacturing (AM) techniques have significantly expanded the potential applications of magnetic materials and devices. This review summarizes various AM methods, including ink‐based and ink‐free processes, and their use in fabricating complex magnetic structures with specific properties tailored for different fields. Key applications discussed include energy‐harvesting devices enhanced with magnetic nanoparticles, water decontamination through magnetically guided microswimmers, and magnetic soft composites in robotics and medical devices. In addition, the integration of AM in producing wearable and flexible magnetic sensors is highlighted, demonstrating its transformative impact on human‐machine interactions. Furthermore, rare‐earth‐free magnets and electric motor designs enabled by AM techniques are also discussed. Despite material compatibility and scalability challenges, AM provides opportunities for creating multifunctional, sustainable devices with reduced waste. Future research should focus on optimizing these techniques for complex applications and large‐scale production, particularly in eco‐friendly and industrial settings. 

This study elucidates how functional property changes in printed sensors across multiple reuse phases and presents a surface-cleaning method for regenerating printable nanoinks. 

This review is focused on non-traditional granular magnetoresistive (MR) sensors. It discusses the underlying physical mechanisms, material configurations, fabrication strategies, and MR device performance evolution over the past two decades. 

One key challenge preventing commercially viable domestic recycling lies in the gap between the high costs of the recycling process and the limited value of recycled raw materials. While additive manufacturing (AM) has the potential to narrow such a gap by converting waste materials into value‐added products through the remanufacturing process, the ink formulation for waste materials remains a formidable task due to poor processability. In contrast to high‐temperature metallurgy (1000–2000 K), a facile approach is developed to convert waste metals (e.g., stainless steel machining chips) into printable and stable inks for 3D‐printed electronics at near room temperature. Moreover, the binder chemistry and percolation mechanism are studied, enabling sustainable ink formulation with non‐toxic solvents and environmentally benign polymers (i.e., no fluorinated polymer). The ink formulation is generalizable for various functional materials, including other metals, carbons, and clays. As a proof of concept, a 3D‐printed strain sensor from recycled stainless steel (SS) chips is demonstrated, which is shown to effectively identify even minor strains from the human body, highlighting potential wearable applications. 

The ever-increasing energy demand has highlighted the need for sustainable, low-carbon, and multi-functional energy solutions. Recently, multi-material additive manufacturing (MMAM) has become an emerging processing approach to prototype energy storage and conversion devices by enabling the fabrication of complex systems in a single, streamlined process while offering design freedom to customize end-product properties at precise, user-defined patterns and geometries. Moreover, it provides opportunities to fine-tune interfaces and material compositions at the microscale, opening new avenues for next-generation energy storage and conversion devices. As MMAM is still in its early stages, a comprehensive understanding of the interplay between material chemistry, processing methods, and device design is fundamental to fully realize its potential for developing high-performance energy materials. This review proposes a framework to bridge the gaps between the fundamental principles of processing physics and the practical implementation of various MMAM techniques in fabricating advanced energy storage and conversion devices, highlighting research challenges and future opportunities. 

This review highlights recent advances in additive manufacturing of rare-earth-free (REF) magnetic materials, emphasizing innovations in material synthesis, ink formulation, printing techniques, and device applications.