Advanced Materials Technologies最新文献

Over the past decade, significant advancements in micro-nano robots have enabled non-invasive operations in hazardous, confined environments, particularly targeting persistent bacterial biofilms in hard-to-reach areas. However, many of these robots are limited by poor magnetic properties, hindering their effectiveness against biofilms. This study proposes a novel strategy using a swarm with strong magnetic effects (Hercules swarm) combined with near-infrared (NIR) light for effective biofilm eradication. Carbonyl iron particles coated with polydopamine (CI@PDA), averaging ≈3 µm in diameter, demonstrate clustering and significant magneto-force under a rotating magnetic field due to their large magnetic saturation. This enables the Hercules swarm to achieve rapid delivery (100 mm s⁻¹), efficient cargo transport (carrying twice its own weight), and effective catheter clearance (1 mm min⁻¹). The controllable motion and high photothermal activity enable precise biofilm eradication without toxic agents. The aggregation of magnetic particles into chains and their rotation are explored by improved particle dynamic model. Simulations also reveal enhanced fluid convection and mechanical pressure around the particle chain. Due to its easy operation, straightforward controllability, and environmental compatibility, the magnetic Hercules swarm emerges as a promising treatment modality for eliminating biofilms entrenched within intricate, narrow, and convoluted medical implants or industrial conduits.

Soft robots have excellent spatial adaptability and high flexibility, but they are limited by the low stiffness of their constituent materials when faced with high-load tasks. In recent years, there have been many works on the development of stiffness-tunable soft actuators by introducing variable stiffness materials into soft actuators, but the existing solutions usually suffer from the problems of slow response, complex structure, and the need of many auxiliary devices to support the completion of the stiffness tuning cycle. This paper proposes a tendon-driven stiffness-tunable soft actuator that addresses these issues. Benefiting from the bidirectional temperature control of thermoelectric modules and the excellent in-plane thermal conductivity of graphene, the actuator is capable of achieving the heating and cooling process by transferring the heat flow through the graphene structure into and out of the shape-memory polymer (SMP) layer of the tendon-driven actuator. This enables stiffness tuning via a single device, reducing the dependence on complex external cooling systems. The use of tendon-driven actuators further eliminates the complex bellow structure of conventional pneumatic actuators and dramatically reduces the size and manufacturing difficulty of individual actuators. Finally, the high load capacity and shape adaptability of the actuator are demonstrated by a gripper equipped with three actuators, which successfully grips objects of various shapes and weights, ranging from less than 10 g to up to 1.6 kg.

In this study, terahertz time-domain spectroscopy (THz-TDS) is employed for the first time to explore the characteristics of mono-, bi-, and tri-layer graphene coated on guided-mode resonance filters (GMRFs). Owing to high quality-factor (Q-factor) resonances of GMRF, the proposed method significantly enhances the resonance depth variation by up to 9.3, 5.1, and 4.2 times at 0.58 THz in TE mode for mono-, bi-, and tri-layer graphene, respectively, in contrast to conventional THz-TDS methods relying on amplitude variation at 0.50 THz in TE mode. Excellent agreement is observed between experimental results and theoretical simulations using the Kubo formula and Drude model, even accounting for variations in sidelobes at an incident angle of 0.6 degrees. Through meticulous fitting process between measurements and simulations for the resonances formed by the GMRF and graphene, the study accurately determines the electrical and optical properties of mono-, bi-, and tri-layer graphene, including frequency-dependent sheet conductivity (σ_s(ω)), mobility (μ), carrier density (N), and Fermi velocity (v_F). Furthermore, in the THz high-frequency region, the observation reveals that as the number of graphene layers increases, the decrease in σ_s(ω) occurs more rapidly than in single-layer graphene, attributed to the screening effect arising from electronic interactions between each graphene layer.

This study introduces a novel frictional mechanical metamaterial composed of a central hexagon or re-entrant honeycomb frame, a lower section with four tapered columns, and an upper portion with a blade shape. When subjected to an external uniaxial force, the 3D structure of the metamaterial utilizes sliding interactions to dissipate frictional energy. The mechanical properties of the proposed metamaterial, such as load-displacement relationships, hysteresis area, and peak force, can be fine-tuned by adjusting geometric parameters and constituent materials. Extensive analysis is conducted through experimental compression tests, finite element (FE) simulations, and theoretical modeling. Comparative assessments of the metamaterial's energy dissipation performance demonstrated a good agreement between experimental and simulation results, with minor variations observed for deeper compression cycles. The proposed metamaterial offers the potential for superior elastic energy absorption and dissipation, making it a promising solution for applications requiring repeated energy dissipation or damping under cyclical loads while maintaining a lightweight profile.

Micro and nanomechanical devices offer enhanced sensing capabilities for detecting biological and chemical small molecules. However, miniaturization necessitates advanced fabrication processes and complex measurement systems, hindering routine sensor analysis. While alternative methods like 3D printing show promise, challenges such as low device resolution persist due to intrinsic damping of polymer inks. In this study, an array of micrometric pillar resonators is fabricated in Ti6Al4 V alloy using additive manufacturing based on laser powder bed fusion technology. These metallic nanomechanical resonators exhibit a very high quality factor with minimal difference between air and vacuum measurements due to low intrinsic damping. Furthermore, titania nanotubes grown on the pillars via anodic oxidation heighten sensitivity for molecular dye degradation evaluation. Leveraging the weak coupling phenomenon among the pillars in the array, these devices facilitate large-scale parallelized measurements, here demonstrated with real-time analysis of dye degradation process. This approach to creating mass sensing devices via metallic additive manufacturing can usher in a new generation of highly performing resonating sensor arrays, offering a cost-effective and efficient alternative to traditional silicon microfabrication methods.

Although 3D micropattern has received considerable attention due to their remarkable usability, the introduction of specific functions, such as “chromism”, is still a challenge mainly due to the lack of adequate functional materials that can be introduced into 3D printing system. In this study, 3D micropatterns with temperature-responsive properties are created by elaborately aligned thermochromic polymer microfibers using charge reversal electro-jet writing (CREW) method with a 3D printer. A reversible color change in response to the temperature change is exhibited in the micropattern, displaying various chromic colors, such as red, blue, and black, at their own thermochromic temperatures. Multiple-color phases can be sequentially expressed in a single structure by incorporating pigments of different colors with distinguishable color shift ranges. Various patterning methods are proposed for manufacturing diverse patterns and demonstrating applications using combinations of color. In addition to directly increasing temperature, the thermochromic process of micropatterns can be induced by heat generated from external factors using electrical energy. These 3D thermochromic micropatterns using the CREW method can be extended to various fields, including sensors, clothing, and anti-counterfeiting.

Recently it is shown that sensitivity of biosensors can be considerably improved using single trap phenomena resulting in two-level random telegraph signal (RTS) switching in current. To develop the transistor structure with a predefined trap position using gold antenna is suggested, which can be excited by light of different intensities to influence the properties of the underlying dielectric layer. High-quality liquid gate-all-around (LGAA) silicon nanowire (NW) field-effect transistor (FET) biosensors are fabricated with a gold bowtie antenna. The transport and noise properties of these new NW FETs are investigated at 940 nm LED excitation in a 1 mm phosphate-buffered saline (PBS) solution with pH = 7.4. A strong sensitivity of I–V and noise characteristics is revealed with an increase in LED intensity. Well-resolved Lorentzian components are only found under the influence of light excitation. A two-level RTS is successfully excited with linear dependence of its amplitude versus intensity. In addition, repeatable fluctuations in current are resolved as small peaks in I–V curves under infrared illumination, thus confirming the excitation of a two-level RTS in the biosensors. The results demonstrate that the FET devices with a gold antenna have significant potential for the excitation of two-level signals to enhance the sensitivity of biosensors.

Recent advances in manufacturing technology and new material processes have enabled novel device designs. As the growing field of robotic tactile sensing calls for advanced tactile sensors, waveguide-based tactile sensors have shown promising mechanisms but system-level integrated solutions are needed to demonstrate their feasibility for sensor applications. In this work, a novel ultra-compact high-resolution tactile sensor based on asymmetric Mach-Zehnder interferometers (MZI) is proposed: PITS (Photonic Integrated Tactile Sensor). It is made from Parylene C waveguides using the Parylene photonic material platform. The sensor is composed of a 4 × 4 array of MZI sensing units and demonstrates multipoint contact sensing as well as shape detection with high sensitivity and low inter-unit crosstalk. The sensing unit is based on multimode interference mechanism explored with supplementary mechanical and optical simulation models. It demonstrates a 0.08 N dynamic range with <0.01 N force resolution, 7.59 signal-to-noise ratio and an average hysteresis of 7.7% over 10 repeated indents. The sensor is fabricated in two layers: a Parylene photonic layer and an align-bonded polydimethylsiloxane (PDMS) micropillar layer on top, which actuates the sensing units. This architecture features a design and fabrication pipeline that allows customizable sensitivity and dynamic range as well as scalable array designs.

Fog represents an underestimated water resource, particularly in arid coastal areas where the abundance of fog makes fog harvesting a highly viable and operational option. In response to the limitations of traditional fog harvesting techniques, biomimetic fog harvesting materials with special wettable surfaces have emerged as a promising solution, offering a notable enhancement in water collection efficiency (WCE). This work presents a bio-inspired multi-strategy fog harvesting material integrated with a wettability contrast pattern and asymmetric wettability. The implementation of multiple strategies at each stage of fog harvesting synergistically improves the WCE of aluminum plates by up to 53%. A solar-powered active fog-collecting system is devised based on this material to cope with changing environments, which demonstrates a significant improvement in WCE compared to a conventional fog net, reaching up to 736.67% under a static fog environment. This work provides a viable design of bio-inspired fog harvesting materials and offers a promising approach for their large-scale implementation.

In this paper, the hydrolysis process of Dichlorohydroxytriazine (NHDT) under alkaline conditions are studied. A qualitative and quantitative method for the determination of HNDT and its hydrolysis products are established, which further clarified the hydrolysis mechanism of NHDT. Under alkaline conditions, the hydrolysis products are mainly compound 4, compound 6 and chloride (Cl⁻). The hydrolysis rate of NHDT at different NaOH concentration and temperature is studied. This research can be used to guide the high efficiency preparation of low fibrillation Lyocell fiber. According to the quantitative detection of wet abrasion numbers and the qualitative analysis of the fiber by SEM after slapping, it is concluded that the low fibrillation Lyocell fiber is less prone to fibrillation under the combined action of wet state and mechanical force. Due to hydrolysis of the unreacted second chlorine resulting in harmful products on the low fibrillation Lyocell fiber, the fibrillation propensity increased with the increase of storage time. The mechanical properties of low fibrillation Lyocell fiber prepared under different fiber states are studied. The tensile breaking strength of low fibrillation Lyocell fiber prepared in the form of sequentially arranged fiber bundles are better, which is closely related to the fiber surface.