Complex 3D Research Articles

3D-AJP: Fabrication of Advanced Microarchitected Multimaterial Ceramic Structures via Binder-Free and Auxiliary-Free Aerosol Jet 3D Nanoprinting.

Manufacturing of ceramics is challenging due to their low toughness and high hardness. Additive Manufacturing (AM) has been explored to create complex ceramic structures, but current techniques face a tradeoff between precisely controlled feature sizes and high shrinkage at the microscales. Here, we introduce 3D-AJP, a novel freeform ceramic fabrication method that enables highly complex microscale 3D ceramic architectures-such as micropillars, spirals, and lattices-with minimal shrinkage and no auxiliary support. Using a near-binder-free nanoparticle ink in an Aerosol Jet (AJ) 3D printer, our approach precisely controls feature sizes down to 20 µm with aspect ratios up to 30:1. The resulting structures exhibit exceptionally low linear shrinkage of 2-6% upon sintering, spanning five orders of magnitude in length scale. Bi-material 3D architectures (zinc oxide/zirconia, zinc oxide/titania, titania/zirconia) and hybrid ceramics further demonstrate the technique's versatility. We showcase two key applications. First, 3D ceramic photocatalysts improve water purification performance, achieving a 400% increase in photocatalytic efficiency compared to bulk ceramics. Second, we develop a highly sensitive Her2 biomarker sensor for breast cancer detection, achieving a 22-second response time and a record-low detection limit of 0.0193 fm. Our technique will lead to high-performance sensing, filtration, microelectronics packaging, catalysis, and tissue regeneration technologies.

Immune cells adapt to confined environments in vivo to optimise nuclear plasticity for migration.

Cells navigating in complex 3D microenvironments frequently encounter narrow spaces that physically challenge migration. While in vitro studies identified nuclear stiffness as a key rate-limiting factor governing the movement of many cell types through artificial constraints, how cells migrating in vivo respond dynamically to confinement imposed by local tissue architecture, and whether these encounters trigger molecular adaptations, is unclear. Here, we establish an innovative in vivo model for mechanistic analysis of nuclear plasticity as Drosophila immune cells transition into increasingly confined microenvironments. Integrating live in vivo imaging with molecular genetic analyses, we demonstrate how rapid molecular adaptation upon environmental confinement (including fine-tuning of the nuclear lamina) primes leukocytes for enhanced nuclear deformation while curbing damage (including rupture and micronucleation), ultimately accelerating movement through complex tissues. We find nuclear dynamics in vivo are further impacted by large organelles (phagosomes) and the plasticity of neighbouring cells, which themselves deform during leukocyte passage. The biomechanics of cell migration in vivo are thus shaped both by factors intrinsic to individual immune cells and the malleability of the surrounding microenvironment.

Kidney Fibrosis In Vitro and In Vivo Models: Path Toward Physiologically Relevant Humanized Models.

Chronic kidney disease (CKD) affects over 10% of the global population and is a leading cause of mortality. Kidney fibrosis, a key endpoint of CKD, disrupts nephron tubule anatomy and filtration function, and disease pathomechanisms are not fully understood. Kidney fibrosis is currently investigated with in vivo models, that gradually support the identification of possible mechanisms of fibrosis, but with limited translational research, as they do not fully recapitulate human kidney physiology, metabolism, and molecular pathways. In vitro 2D cell culture models are currently used, as a starting point in disease modeling and pharmacology, however, they lack the 3D kidney architecture complexity and functions. The failure of several therapies and drugs in clinical trials highlights the urgent need for advanced 3D in vitro models. This review discusses the urinary system's anatomy, associated diseases, and diagnostic methods, including biomarker analysis and tissue biopsy. It evaluates 2D and in vivo models, highlighting their limitations. The review explores the state-of-the-art 3D-humanized in vitro models, such as 3D cell aggregates, on-chip models, biofabrication techniques, and hybrid models, which aim to mimic kidney morphogenesis and functions. These advanced models hold promise for translating new therapies and drugs for kidney fibrosis into clinics.

Reduced-order modeling for complex 3D seismic wave propagation

Summary Elastodynamic Green’s functions are an essential ingredient in seismology as they form the connection between direct observations of seismic waves and the earthquake source. They are also fundamental to various seismological techniques including physics-based ground motion prediction and kinematic or dynamic source inversions. In regions with established 3D models of the Earth’s elastic structure, such as southern California, 3D Green’s functions can be computed using numerical simulations of seismic wave propagation. However, such simulations are computationally expensive which poses challenges for real-time ground motion prediction and uncertainty quantification in source inversions. In this study, we address these challenges by using a reduced-order model (ROM) approach that enables the rapid evaluation of approximate Green’s functions. The ROM technique developed approximates three-component time-dependent surface velocity wavefields obtained from numerical simulations of seismic wave propagation. We apply our ROM approach to a 50 km × 40 km area in greater Los Angeles accounting for topography, site effects, 3D subsurface velocity structure, and viscoelastic attenuation. The ROM constructed for this region enables rapid computation (≈0.0001 CPU hours) of complete, high-resolution (500 m spacing), 0.5 Hz surface velocity wavefields that are accurate for a shortest wavelength of 1.0 km for a single elementary moment tensor source. Using leave-one-out cross validation, we measure the accuracy of our Green’s functions for the CVM-S velocity model in both the time domain and frequency domain. Averaged across all sources, receivers, and time steps, the error in the rapid seismograms is less than 0.01 cm/s. We demonstrate that the ROM can accurately and rapidly reproduce simulated seismograms for generalized moment tensor sources in our region, as well as kinematic sources by using a finite fault model of the 1987 MW 5.9 Whittier Narrows earthquake as an example. We envision that rapid, accurate Green’s functions from reduced-order modeling for complex 3D seismic wave propagation simulations will be useful for constructing real-time ground motion synthetics and source inversions with high spatial resolution.

Study of evolution for 3D structured surface with nano-balls and walls-like features with thickness variation for WO3 thin films made by spray deposition

The present work regards a unique yet study of 3D structured surface evolution of nano-balls and walls-like features with thickness variation, for tungsten oxide (WO3) thin films made by spray deposition. Since in most optoelectronic applications the surface morphology and structure play a crucial role and WO3 is one of the most studied and used metal oxide semiconductors in a significant variety of optoelectronic applications, a detailed study of recently observed and reported unique 3D complex architecture of WO3 coatings fabricated by spray pyrolysis (starting from different precursors) is of great importance for further development of thin film coatings and devices. In this scope, two different series of WO3 of 11 samples with different thicknesses each, starting from two tungsten peroxide precursor concentrations (0.05 M and 0.1 M) were fabricated by spray pyrolysis and thoroughly characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction and Raman spectroscopy. Results suggest that, for the mentioned concentrations, the main structural differences affect mostly the surface morphology and slightly the surface texturing. These observations prove the reliability of fabrication of coatings with such surface morphology by spray pyrolysis method and open new perspectives for better sensors, electrochromic or photochromic devices, and more.

Designing Spiking Neural Network-Based Reinforcement Learning for 3D Robotic Arm Applications

This study investigates a novel approach to robotic arm control through integrating spiking neural networks with the twin delayed deep deterministic policy gradient reinforcement learning algorithm. Specifically, it presents the first application of spiking neural networks-based twin delayed deep deterministic policy gradient in 3D robotic manipulation, demonstrating its extension from traditional 2D tasks to complex 3D target-reaching scenarios with improved energy efficiency and stability. Additionally, with the inertial measurement unit data the system successfully mimics human arm movements, achieving a success rate of 0.95 among 50 trials and enabling an intuitive and accurate human–robot interaction system. This pioneering attempt highlights the feasibility of combining the biologically inspired spiking neural networks with the reinforcement learning algorithm to address the real-time challenges in high-dimensional robotic environments and advance the field of human–robot interaction systems.

Complex 3D surface structuring by means of laser chemical machining with modulated laser power

Laser chemical machining (LCM) utilizes the thermal induced chemical dissolution to remove the material far below the melting temperature. Material removal during LCM with modulated laser power depends on the modulation frequency applied. The spatial frequency of the depth’s oscillation corresponds to the spatial frequency of the laser power up to the threshold frequency. Above this threshold, the removal depth remains constant. The aim of this work is to investigate whether modulated laser power could be used for surface structuring and its influence on the wetting behavior. Therefore, line scans with different overlaps were generated to create a surface structure on titanium grade 1 using a rectangular function of the output power with frequencies below the threshold. In addition to the modulation frequency and the line overlap, the phase angle between two neighboring lines was also studied. Subsequently, a wide range of surface structures was achieved, including wavelike and braidlike structures. The wettability investigation highlighted the considerable impact of the line overlap on the wetting behavior of the surfaces produced. While higher overlaps caused an isotropic wetting, lower overlaps induced an anisotropic wetting. These results, thus, demonstrate for the first time the possibility of achieving anisotropic wetting behavior by LCM processing.

3D Mechanical Response Stem Cell Complex Repairs Spinal Cord Injury by Promoting Neurogenesis and Regulating Tissue Homeostasis.

Spinal cord injury (SCI) leads to acute tissue damage that disrupts the microenvironmental homeostasis of the spinal cord, inhibiting cell survival and function, and thereby undermining treatment efficacy. Traditional stem cell therapies have limited success in SCI, due to the difficulties in maintaining cell survival and inducing sustained differentiation into neural lineages. A new solution may arise from controlling the fate of stem cells by creating an appropriate mechanical microenvironment. In this study, mechanical response stem cell complex (MRSCC) is created as an innovative therapeutic strategy for SCI, utilizing 3D bioprinting technology and gelatin microcarriers (GM) loaded with mesenchymal stem cells (MSCs). GM creates an optimal microenvironment for MSCs growth and paracrine activity. Meanwhile, 3D bioprinting allows accurate control of spatial pore architecture and mechanical characteristics of the cell construct to encourage neuroregeneration. The mechanical microenvironment created by MRSCC is found to activate the Piezo1 channel and prevent excessive nuclear translocation of YAP, thereby increasing neural-related gene expression in MSCs. Transplanting MRSCC in rats with spinal cord injuries boosts sensory and motor recovery, reduces inflammation, and stimulates the regeneration of neurons and glial cells. The MRSCC offers a new tissue engineering solution that can promote spinal cord repair.

An Innovative Deposition Technology for Conductive & Dielectric Materials

Electronics manufacturers’ roadmaps are pushing the boundaries of dispensing to levels where new capabilities and new technologies are needed. Materials are expected to be deposited at always higher resolutions. Various process solutions are being offered, but these always require tradeoffs. Higher resolutions come at the expense of having to use custom materials, such as in inkjet, or lower speed, such as in dispensing. Ideally,ly, we would discover a a process concept solution that has thewould should combine allow to keep the throughput of traditional analog solutions, such as screen printing, with the accuracy and flexibility of traditional digital solutions, such as jetting and needle dispensing, while using industry standard materials, in a and offering a greener approacsustainable and cost effective manner. With Continuous Laser Assisted Deposition (CLAD), there is no more tradeoff between materials and other parameters. ioTech’s contactless technology is nozzle and mesh-free. In the CLAD dispensing process, materials are evenly coated on a transparent carrier film and then exposed to a laser beam. The laser applies a short burst of energy which releases perfectly consistent drops of material onto the substrate below. The deposited material can then be sintered or cured inline. A very wide range of geometries and form factors can be achieved. CLAD can deposit material drops at high speed and high resolution. The viscosity window includes standard certified materials between 500cPs and 500,000cPs, without the need for any reformulation. Most materials can be printed, including conductive materials, polymers, carbon inks, ceramics pastes and silicone. The CLAD deposition technology can be used for multiple applications. In this presentation, we will focus on applications related to SEMI packaging and µelectronics applications, such as conductive and dielectric deposition. We will highlight examples such as RDL/Fan Out structures and Flip Chips pillars. The system’s multi material printing feature comes with embedded post-processing options such as heat and UV curing, sintering and ablation. This combination delivers a unique capability to build multi-functional 3D structures. The CLAD technology provides manufacturers with unmatched design flexibility, high productivity, and a major sustainability advantage vs existing technologies. As the system process also allows for the concurrent deposition and curing of up to five different materials, we will also study the case of complex 3D interconnects. CLAD and its multiple benefits have been warmly welcomed by the industry, leading to multiple awards, and attracting prestigious semiconductor customers.

Effect of Thermal Reflow on Microstructural Morphology and Contact Mechanics in the Photo-Lithographic Fabrication of Biomimetic Adhesive Materials.

Bionic adhesive materials with 3D complex micro/nanostructures have several advantages of low preload, strong adhesion, switchable adhesion, etc. As the primary high-precision fabrication method for such materials, lithography is inherently limited by its 2D processing capabilities. Achieving complex 3D morphologies typically requires auxiliary processes, such as dipping and double-sided separate UV exposures, which increase both the complexity and limitations of the fabrication process. In this work, an efficient dimensional regulation method-the photo-lithographic thermal reflow is proposed. The technique utilizes the intrinsic properties of photoresist materials, introducing thermal energy to transform microstructures from 2D to 3D. Mushroom-shaped morphology is taken as an example to fabricate bionic adhesive materials. The fabricated mushroom-shaped micropillar arrays exhibit different tendencies in adhesion force, friction, reversible adhesion, and repeatability, demonstrating the precise tunability of the micropillar geometry. The optimized mushroom-shaped adhesive material not only exhibits the adhesion force of up to 12.26 N on the silicon surface (superior to that of a single foot of gecko (10 N)) but also shows superior friction, easy peeling and high durability. The result demonstrates that this method enables rapid and efficient regulation of 3D morphology and provides a novel approach for the fabrication of complex micro/nanostructure.

Polarization-controlled metasurface for simultaneous holographic display and three-dimensional depth perception

Abstract Simultaneous optical display and depth perception are crucial in many intelligent technologies but are usually realized by separate bulky systems unfriendly to integration. Metasurfaces, artificial two-dimensional optical surfaces with strong light–matter interaction capabilities at deep subwavelength scales, offer a promising approach for manufacturing highly integrated optical devices performing various complex functions. In this work, we report a polarization-multiplexed metasurface that can functionally switch between holographic display and Dammann gratings. By tailoring the incidence polarization, the metasurface can display high-quality holographic images in the Fresnel region or project a uniform spot cloud nearly covering the entire 180° × 180° transmissive space. For the latter, a projection and three-dimensional (3D) reconstruction experiment is conducted to elaborate the potential in retrieving 3D complex spatial information. The current results provide a prominent way to manufacture lightweight and highly-integrated comprehensive imaging systems especially vital for cutting-edge intelligent visual technologies.

Building blocks for nanophotonic devices and metamaterials.

Nanophotonic devices control and manipulate light at the nanometer scale. Applications include biological imaging, integrated photonic circuits, and metamaterials. The design of these devices requires the accurate modeling of light-matter interactions at the nanoscale and the optimization of multiple design parameters, both of which can be computationally demanding and time intensive. Further, fabrication of these devices demands a high level of accuracy, resolution, and throughput while ideally being able to incorporate multiple materials in complex geometries. To address these considerations in the realization of nanophotonic devices, recent work within our lab has pursued the efficient and accurate modeling of nanoparticles and the assembly of complex 3D micro- and nanostructures using optical tweezers. This Feature Article review highlights these developments as well as related efforts by others in computation and fabrication methods related to nanophotonic devices and metamaterials.

A Solvatochromic Aluminum-1,8-Naphthalimide Complex 2D Nanostructure as a Versatile Probe for Sudan III Detection and Forensic Analysis

A Solvatochromic Aluminum-1,8-Naphthalimide Complex 2D Nanostructure as a Versatile Probe for Sudan III Detection and Forensic Analysis

3D 형상의 자동차 도어트림(Door Trim)을 인식 재봉하는 로봇 설계

Currently, the sewing industry is experiencing a decline in the number of technicians because approximately 77.7% of domestic sewing technicians (primarily those in their 50s and 60s) are retiring, with little to no influx of new technicians in their 20s and 30s. This has led to a continuous decrease in the number of highly experienced sewing technicians besides the challenges in recruiting new technicians. Furthermore, there is a shortage of technicians skilled in sewing complex 3D door trims, resulting in productivity issues. This study addresses these challenges by developing an AI-powered robotic sewing solution for recognizing and stitching intricate 3D door trim lines.

Induction of MASH in three-dimensional bioprinted human liver tissue.

Metabolic dysfunction-associated steatohepatitis (MASH), formerly known as nonalcoholic steatohepatitis (MASH), is a major risk factor for cirrhosis and hepatocellular carcinoma (HCC) and a leading cause of liver transplantation. MASH is caused by an accumulation of toxic fat molecules in the hepatocyte which leads to inflammation and fibrosis. Inadequate human "MASH in a dish" models have limited our advances in understanding MASH pathogenesis and in drug discovery. This study uses complex multicellular 3D bioprinting, combining hepatocytes with nonparenchymal cells in physiologically relevant cell ratios using biocompatible hydrogels to generate bioinks Bioprinted human liver tissues consisting of the four major cell types, (hepatocytes, liver endothelial cells, Kupffer cells, and hepatic stellate cells) are generated from cells purified from normal human livers, using this complex bioprinting platform. These liver tissues are incubated in a cocktail consisting of fatty acids, lipopolysaccharide (LPS), and fructose to produce a MASH phenotype in comparison to liver tissues incubated in control media. Furthermore, these bioprinted liver tissues are of sufficient size to undergo histological processing and immunohistchemistry comparable to classic clinical pathological analysis. The MASH liver tissues develop hepatocyte steatosis, inflammation, and fibrosis, in response to the MASH induction media. Additionally, the transcriptome of the MASH tissues differed significantly from the healthy tissues and more closely resembled the transcriptome of biopsies of MASH livers from patients Thus, this study has developed a MASH bioprinted liver tissue suitable for studies on pathophysiology and drug discovery.

Exciton Collimation, Focusing and Trapping Using Complex Transition Metal Dichalcogenide Lateral Heterojunctions

AbstractControlling the motion of neutral excitons in optically active media is a mandatory development to enable the conception of advanced circuits and devices for applications in excitronics, quantum photonics, and optoelectronics. Recently, proof of unidirectional exciton transport from high‐ to low‐bandgap material is evidenced using a high‐quality lateral heterostructure separating transition metal dichalcogenide monolayers (TMD‐MLs). In this paper, by combining room‐temperature micro‐photoluminescence far‐field imaging with a statistical description of exciton transport, the underlying excitonic local distribution and fluxes taking place near lateral heterojunctions are unveiled. The complex 2D excitonic transport properties found near a linear interface separating WSe2 from MoSe2 TMD‐MLs are studied and reveal two distinct diffusion regimes profoundly affecting the effective diffusion length. Then, it is shown that combining two and three of these interfaces, allows advanced in‐plane control of the excitonic distribution and flux over large distances. Exciton focalization and trapping, allowing an increase in the local exciton density up to three orders of magnitude are demonstrated. Finally, flux collimation is achieved with the formation of parallel current lines extending a few micrometers away from the source. We believe that the deterministic shaping and positioning of the exciton distribution and flux shown here will be key toward the conception of realistic excitronic devices.

Inorganic/Inorganic Composites Through Emulsion Templating.

Inorganic/inorganic composites are found in multiple applications crucial for the energy transition, from nuclear reactors to energy storage devices. Their microstructures dictate their properties from mass transport to fracture resistance. Consequently, there has been a multitude of processes developed to control them, from powder mixing and the use of short or long fibers, to tape casting for laminates up to recent 3D printing. Here, emulsions and slip casting are combined into a simpler, broadly available, inexpensive processing platform that allows for in situ control of composite microstructure while also enabling complex 3D shaping. This study shows that slip casting of emulsions triggers a two-step solvent removal, opening the possibility for the conformal coating of pores. This process is showcased by producing strong and lightweight alumina scaffolds reinforced by a conformal zirconia coating. In addition, by manipulating magnetically responsive droplets, their distribution can be controlled, allowing for the formation of inorganic fibers inside an inorganic matrix in situ during slip casting. Using this approach, alumina has been reinforced with aligned metallic iron fibers to prepare composites with a work of fracture an order of magnitude higher than the pure ceramics.

Nearfield observation of spin-orbit interactions at nanoscale using photoinduced force microscopy.

Optical spin and orbital angular momenta are intrinsic characteristics of light determined by its polarization and spatial degrees of freedom, respectively. At the nanoscale, sharply focused structured light carries coupled spin-orbital angular momenta with complex 3D nearfield structures, crucial for manipulating multidimensional information of light in nanophotonics. However, characterizing these interactions faces challenges with conventional farfield-based methods, which typically lack the essential accuracy and resolution to interrogate the structured nearfield with high fidelity. To address this challenge, we experimentally observe spin-orbit interactions at the nanoscale using photoinduced force microscopy. Such interactions are enabled through sharply focused circularly polarized optical vortices, which are then mapped by nearfield optical forces in high resolution. Because the optical forces can reveal both longitudinal and transverse nearfield structures with high fidelity, the spin-orbit interactions are eventually evaluated quantitatively at the nearfield, as an important inspiration to use the coupled momenta in dense optical nano-device systems.

Instruction-responsive programmable assemblies with DNA origami block pieces.

DNA nanotechnology has created a wide variety of nanostructures that provide a reliable platform for nanofabrication and DNA computing. However, constructing programmable finite arrays that allow for easy pre-functionalization remains challenge. We aim to create more standardized and controllable DNA origami components, which could be assembled into finite-scale and more diverse superstructures driven by instruction sets. In this work, we designed and implemented DNA origami building block pieces (DOBPs) with eightmutually independent programmable edges and formulated DNA instructions that tailored such components. This system enables DOBPs to be assembled into one or more specific 2D arrays according to the instruction sets. Theoretically, a two-unit system can generate up to 48 distinct DNA arrays. Importantly, experiments results demonstrated that DOBPs are capable of both deterministic and nondeterministic assemblies. Moreover, after examining the effects of different connection strategies and instruction implementations on the yield of the target structures, we assembled more complex 2D arrays, including limited self-assembly arrays such as 'square frames', 'windmills' and 'multiples of 3' long strips. We also demonstrated examples of Boolean logic gates 'AND' and 'XOR' computations based on these assembly arrays. The assembly system provides a model nano-structure for the research on controllable finite self-assembly and offers a more integrated approach for the storage and processing of molecular information.

Computing the multimodal stochastic dynamics of a nanobeam in a viscous fluid

The stochastic dynamics of small elastic objects in fluid are central to many important and emerging technologies. It is now possible to measure and use the higher modes of motion of elastic structures when driven by Brownian motion alone. Although theoretical descriptions exist for idealized conditions, computing the stochastic multimodal dynamics for the complex conditions of an experiment is very challenging. We show that this is possible using deterministic finite-element calculations with the fluctuation dissipation theorem by exploring the multimodal stochastic dynamics of a doubly clamped nanobeam. We use a very general, and flexible, finite-element computational approach to quantify the stochastic dynamics of multiple modes simultaneously using only a single deterministic simulation. We include the experimentally relevant features of an intrinsic tension in the beam and the influence of a nearby rigid boundary on the dynamics through viscous fluid interactions. We quantify the stochastic dynamics of the first 11 flexural modes of the beam when immersed in air or water. We compare the numerical results with theory, where possible, and find excellent agreement. We quantify the limitations of the computational approach and describe its range of applicability. These results pave the way for computational studies of the stochastic dynamics of complex 3D elastic structures in a viscous fluid where theoretical descriptions are not available.