Search for: All records

Abstract Although metal-polymer heterogeneous structures possess exceptional mechanical, thermal, and electrical properties, their fabrication remains challenging due to the reactive nature of the materials and the risk of property alteration during manufacturing. This study investigates the printing quality of metal-polymer structures fabricated using electrically assisted heterogeneous material printing (EF-HMP), focusing on the relationship between the polymer and metal layers and their electrical properties. The developed printing solution enables the transport of metal ions for metal printing onto a polymer matrix under a controlled electrical field. The study emphasizes the critical role of polymer microstructures in influencing metal electrodeposition, including printing time and morphology. Three microstructure geometries—rectangular, trapezoidal, and semicircular—were designed based on manufacturability and surface-area-to-volume ratio and evaluated for their impact on metal-polymer fabrication via EF-HMP process. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and electrical conductivity tests revealed that the semicircular microstructure provided the best printing performance, forming a robust metal structure in a short time and achieving the lowest resistance of 12 kΩ. This research highlights the potential of EF-HMP for metal-polymer fabrication, offering new insights into the influence of interfacial polymer microstructures on metal printing at room temperature. These findings pave the way for optimizing the design and functionality of metal-polymer components in metamaterials, thermal management, and flexible electronics applications. 

Laser based additive manufacturing (AM) methods, that incorporate a high-density laser to sinter, melt, or solidify the desired material, have developed into an ideal technology for the design and fabrication of robust and highly customizable functional devices which aim to address key challenges in the aerospace, biomedical, and defense sectors. Recent advancements in powder bed fusion (PBF) approaches, such as selective laser sintering (SLS) and melting (SLM) have significantly improved the range of printable materials, minimum feature size, and microstructure evolution, endowing precise control over the physical properties of the final printed part. Furthermore, studies on novel photoresist materials and laser scanning strategies used during multiphoton lithography (MPL) approaches indicated that nanoscale spatial resolution could be achieved, allowing for the design of intricate biomedical implants or smooth optical devices. This chapter focuses on an extensive review of current research being conducted on laser-based AM technologies highlighting the current compatible materials and applications of SLS, SLM, and MLP printed functional devices. Future perspectives and notable challenges of the laser-based AM technologies are discussed in detail with the purpose of identifying critical research areas for each methodology. 

Abstract The cell is a microcapsule system wherein biological materials are encapsulated by a thin membrane, which provides valuable information on the metabolism, morphology, development, and signal transduction pathways of the studied cell. The cell-inspired microdroplet has the characteristics of efficient nanoscale substance transportation, self-organization, and morphological adaptation. However, it is extremely difficult to manufacture such systems. Mostly vesicles such as liposomes, polymersomes, and microcapsules are first produced by a high-pressure homogenizer and microfluidizer as an emulsion and then encapsulated microcapsules by the drop or emulsion method. Currently, acoustic levitation opens entirely new possibilities for creating bioinspired microdroplets because of its ability to suspend tiny droplets in an antigravity and noncontact manner. Herein, we propose contactless printing of single-core or multi-core cell-inspired microdroplets via acoustic levitation. First, the oscillation mode and microscopic morphology of the droplets under different ultrasonic vibration frequencies are shown by simulation, and the curing characteristics of the shell structure under different ultraviolet illumination conditions are quantitatively measured. The feasibility of manufacturing multi-core microdroplets and manufacturing submillimeter-scale particles based on oil trapping is extensively studied. To explore the morphological adaptability of microdroplets, ferromagnetic Fe3O4 nanoparticles are used to give magnetic-responsive properties to cells, and the microscopic deformation and motion in microfluidic channels under the magnetic field are characterized. Finally, the proposed printing method proves the versatility of in-space contactless printing of complex 3D beam structures and provides a powerful platform for developing biomedical devices and microrobots and studying morphogenesis and synthetic biological systems. 

Abstract This paper presents a scalable and straightforward technique for the immediate patterning of liquid metal/polymer composites via multiphase 3D printing. Capitalizing on the polymer's capacity to confine liquid metal (LM) into diverse patterns. The interplay between distinctive fluidic properties of liquid metal and its self‐passivating oxide layer within an oxidative environment ensures a resilient interface with the polymer matrix. This study introduces an inventive approach for achieving versatile patterns in eutectic gallium indium (EGaIn), a gallium alloy. The efficacy of pattern formation hinges on nozzle's design and internal geometry, which govern multiphase interaction. The interplay between EGaIn and polymer within the nozzle channels, regulated by variables such as traverse speed and material flow pressure, leads to periodic patterns. These patterns, when encapsulated within a dielectric polymer polyvinyl alcohol (PVA), exhibit an augmented inherent capacitance in capacitor assemblies. This discovery not only unveils the potential for cost‐effective and highly sensitive capacitive pressure sensors but also underscores prospective applications of these novel patterns in precise motion detection, including heart rate monitoring, and comprehensive analysis of gait profiles. The amalgamation of advanced materials and intricate patterning techniques presents a transformative prospect in the domains of wearable sensing and comprehensive human motion analysis.