Advanced Materials Technologies最新文献

The fabrication of durable and high anticorrosion hydrogel composite materials composed of multi-walled carbon nanotubes (MCNTs) and crosslinked polyacrylic acid (PAA) for EMI shielding application is reported. The MCNTs contribute to the generation of 3D porous structures and enhance the mechanical properties of composite hydrogel. The 3D porous structure and high electrical conductivity inherited from ultrahigh electrically conductive MCNTs enable excellent EMI shielding properties with a total shielding efficiency EMI SE (SE_T) value of 32.8 dB (>99.9%) at only 3 wt% filler content of MCNTs. The MCNTs/PAA hydrogels also display superior EMI shielding performance under a strong acidic environment with SE_T > 99.99% while the 3D porous structure remained intact. The combination of electron–ion system in pH solution enriches the charge transfer and accumulation, enabling dipole orientation and polarization that are favorable for enhancing EMI attenuation. Moreover, the porous structure of MCNTs/PAA also contributes to partial trapping and dissipation of EM radiation energy via multiple scattering phenomena. This work thus paves the way toward applications of 3D hierarchical network materials for EMI shielding applications in both land and aqueous environments.

Microscopic defects in the amorphous regions of natural cellulose affect the mechanical properties of their materials. After dissolution and regeneration, cellulose's mechanical properties are still insufficient for application in advanced materials. Conventional compounding and crosslinking techniques with toxic crosslinking agents are not only cumbersome, but also have limited performance enhancement in cellulose materials Therefore, much attention has been paid to designing and developing more straightforward and efficient cellulose reinforcement technologies. Herein, an in situ multiscalarization strategy is used to form multiscale silk fiber-cellulose composites (MS-C) by the gradual nanosizing of silk fibers (SF) under heating in a 1-butyl-3-methylimidazolium chloride solution of cellulose (Cel-BmimCl). MS-C are constructed from micro and nano SF, fibroin chains, and cellulose molecules into a multidimensional network. Due to its advantage of multiscale structure, MS-C has excellent mechanical properties, the tensile strength and Young's modulus, which are 123.06% and 91.68% higher than that of pure regenerated cellulose after 5h heating treatment. Besides, MS-C has good biocompatibility and can be molded or 3D printed with direct ink writing, showing broad application prospects in medical, bioengineering, and other fields. This multiscale enhancement strategy can also be extended to the research and application of biopolymers such as natural polysaccharides or proteins.

Metallic nanostructures hold immense promise for radiative heating technology because of their distinctive capability to simultaneously achieve high mid-infrared reflectance and generate vibrant colors through structural or plasmonic effects. However, fabricating metallic nanostructures remains challenging using traditional top–down techniques. Here, the solid-state superionic stamping (S4) process is demonstrated as a scalable and economical tool to electrochemically imprint metallic grid nano-patterns onto flexible substrates. With precise control over grid width and length at the nanoscale, the S4 approach enables the fabrication of nano-patterned grid coatings exhibiting a spectrum of colors. These coatings also show high mid-infrared reflectance exceeding 80% at 9.5 µm, leading to radiative heating effects of 5.9 and 3.1 °C compared to bare skin and cotton, respectively. This work introduces a viable strategy for creating colored infrared-reflective patterns, paving the way for diverse thermal management applications.

Multifunctional Energy-Integrated Devices

Advanced multifunctional devices seamlessly integrate energy modules with electronic components and circuits, powering smart applications such as artificial intelligence, robotics and so on, demanding the future power sources to be the combination of multiple energy forms, high energy density, security, and miniaturization. More details can be found in the Guest Editorial by Guozhen Shen (2401273).

The tunable and reversible fabrication function of stealth metasurfaces has significant application value in complex electromagnetic environments., but the extremely low fault tolerance of the existing fabrication methods limits their further development and utilization. In this manuscript, a design and fabrication method for rewritable broadband stealth metasurfaces with memory function is proposed. The reversible phase transition is achieved by laser induced germanium telluride (GeTe) film, which provides the possibility for metasurface to realize the rewriting function. The process of laser induced GeTe and the simulation model of GeTe are investigated, and the conclusions are verified by rewritable broadband polarization converter (RBPC) and rewritable broadband lossy absorber (RBLA). The experimental results show that the reflectivity of fabricated RBLA is less than −10 dB in the range of 7.8–16.1 GHz, which is in good agreement with the numerical simulation results. Meanwhile, there is a highly consistent performance effect before and after repeated induction. The research has the advantages of high efficiency, region selectivity, non volatility and high fault tolerance, which can provide new manufacturing ideas and good candidates for tunable metamaterials.

Porous radiative cooling polymers have drawn significant attention for passive daytime cooling due to their desirable cooling performance and easy scalability. Since optimal pore parameters (i.e., pore diameter and porosity) will enhance light scattering, polymethyl methacrylate (PMMA) powders are sintered to fabricate samples with different pore parameters by the one-step full-dry powder sintering method. These samples have a hierarchically porous structure with pore diameters <5.0 µm. The most porous sample has 43% porosity, 0.964 reflectance in the 0.3–2.5 µm wavelength range, and 0.967 emittance in 8–13 µm wavelength range (which is the atmospheric window). The measured cooling temperature difference decreases when the porosity is low for hierarchically porous PMMA with similar pore size distribution. The high sub-ambient cooling temperature reduction provided by hierarchically porous PMMA with optimal pore parameters is due to high solar reflectance when illuminated by the sun. Similar cooling trends are evident when sunlight is simulated by a Xenon lamp and an optical filter. The powder-sintered hierarchically porous PMMA with optimal pore parameters can be an excellent radiative cooler for passive daytime cooling applications.

Soft actuators have great potential applications in sophisticated movement and sensitive devices due to their flexible nature, good interaction, and precise control. However, existing carbon-based optical actuators are limited in their response under visible light irradiation. The limited visible light absorbance of the carbon nanostructure brought the metallic nanoparticle into the soft actuators that can absorb visible light. This study introduces a new type of plasmonic photothermal-bimorph actuator, using graphene oxide (GO), reduced graphene oxide (rGO), and silver nanorods (Ag NRs) to overcome the limitations of traditional optical actuators. The bimorph film is actuated by visible and near-infrared light stimuli with various power densities showing reversible deformation behavior. The actuator shows significant bending associated with a ≈50° change in bending angle under visible light irradiation with a response time of ≈5 ± 1 sec. Furthermore, a smart photo-controlled non-contact switch is fabricated based on photo-thermal conversion properties, demonstrating perfect integration of plasmonic bimorph actuators. The density functional theory based molecular dynamics calculations provide an additional understanding of the bending of actuators under external stimulus. Using illustrative demonstrations of actuators, these results hint at a method for generating multipurpose visible light-based soft robots, supporting a new approach to developing an optical locking system.

Digital nucleic acid quantification has emerged as an exceptionally valuable technique in molecular diagnosis, capturing significant attention in the biomedical field. This study introduces a novel multi-volume digital loop-mediated isothermal amplification (dLAMP) chip that offers an extensive detection range and user-friendly operation. The chip consists of 1024 large chambers with the volume of 7.2 nL and 6400 small chambers with the volume of 0.064 nL. The ingenious combination of chambers with volume difference beyond a 100-fold on the single chip enables a broad dynamic range exceeding 10⁵ for nucleic acid quantification. Furthermore, this chip incorporates an automated strategy, enabling the rapid loading and partitioning of the reaction mixture into subvolumes within 4 min. In order to evaluate the quantitative capability of the multi-volume dLAMP chip, a 10-fold serial dilution of the β-actin DNA template is measured. Additionally, the chip is tested for β-actin DNA concentration in plasma samples from colorectal cancer patients and healthy individuals. By providing enhanced automation, wide dynamic range, and improved accuracy, this chip paves the way for broader applications and the advancement of biomedical research fields.

As the scaling down of semiconductor devices reaches its physical limits, 3D stacking packaging technology is emerging as a new miniaturization solution. Among the various 3D packaging technologies, Cu direct bonding is widely adopted due to copper's excellent electrical conductivity and the absence of intermetallic compounds for solder bumps. Since copper readily undergoes oxidation, technologies that prevent Cu surface oxidation during Cu direct bonding are essential. However, current research suggests that the methods require additional pretreatment processes, which demand high costs. In this study, a Cu direct bonding method utilizing glycerol vapor is developed to effectively streamline the pretreatment steps. The potential of glycerol as a reducing agent and antioxidant for Cu is demonstrated using a silicon die sample with a size of 10  ×  10 mm², verified through the X-ray photoelectron spectroscopy. The Cu direct bonding for 3D semiconductor packaging is successfully performed under glycerol vapor atmosphere, without any plasma pretreatment. The cross-section of the bonded specimens is examined by scanning electron microscopy, and mechanical reliability is assessed by die shear testing.