Advanced Materials Technologies最新文献

Stretchable film strain sensors show potential applications in healthcare and human-machine interfacing, while poor signal linearity restricts their practical applications owing to inaccurate and instable strain indication. Signal sensitivity and linearity can be improved via constructing hetero-modulus microstructure on elastomeric substrate to some extent, though it is challenging to construct hetero-structure with distinct modulus differences for electrical signal linearity modulation over a wide strain range. Herein, a simple strategy is proposed to tune signal sensitivity, linearity, and detection range of stretchable strain sensors by adjusting the distribution of rigid polystyrene (PS) nanospheres coated on electrospun thermoplastic polyurethane (TPU) fiber mats. Heterostructure characteristics can be controlled by spray coating times of PS nanospheres, which are immobilized onto the fiber mats by weak swelling of TPU and the linking layer of reduced graphene oxide (rGO) between TPU and PS induced by hydrogen bonding and π–π stacking. Relatively, the sensors with moderate spray coating times of PS nanospheres show balanced signal sensitivity and linearity over a strain range of 0–80%, as well as fast response to tensile strain and good signal reproducibility. Such elastomeric film strain sensors can be used for monitoring physiological activities and interfacing human hand and bionic fingers.

A comprehensive strategy to enhance the polarization performance of mid-wave infrared photodetectors (PDs) is developed and implemented by integrating wire-grid polarizers (WGPs) using nanoimprint lithography and femtosecond laser (FSL) polishing. This combined approach offers significant advantages, including large-area fabrication capabilities, practical device integration, and improved polarization characteristics. By addressing optical losses, the primary factor contributing to polarization degradation through the thermal effects of FSL polishing, substantial improvements are achieved in surface roughness and grain boundary reduction on the WGP, resulting in remarkable performance enhancements. As a result, the extinction ratio of the integrated WGP InAs/GaSb type-II superlattice PD achieves an impressive value of up to 1044. This approach holds promising potential for advancing polarization-based imaging and measurement systems to new heights.

Large size high-quality perovskite single-crystals are highly desirable for investigating their fundamental materials properties and realizing state of the art electronic/optoelectronic device performance. Herein, a novel single-crystal growth method is reported by recrystallization of perovskites in oversaturated solutions. Perovskite single crystals including both organic–inorganic hybrid metal halides and their all-inorganic counterparts can be obtained in large amounts by this method. All of the synthesized perovskite single crystals exhibit large crystal sizes (centimeter level) and exceptional light emission properties. Meanwhile, the single-crystal growth can be well controlled and the solvent can be reused for cycles of single-crystal growth, which sheds light on the preparation of perovskite materials in a way of green chemistry. In addition, thermodynamic growth principles for the single-crystal growth are proposed, providing a universal approval for metal halide single-crystal synthesis.

Phase change fibers with multifunctionalities are a promising material for thermal management applications, however, it is still challenging to simultaneously give the fiber high energy conversion and storage capacity. Here, a cooperative in situ impregnation strategy is reported, to introduce Au nanoparticles (NPs) and polyethylene glycol (PEG) together into carbon nanotube (CNT) network during the expansion process, resulting in a CNT/Au/PEG composite phase change fiber. The obtained composite fiber have the characteristics of high loading (up to 88.0–98.6%) and uniform distribution of Au NPs, and thus exhibits superior mechanical, electrical, and thermal properties. The presence of Au NPs plays more important role in not only improving the PEG crystallinity and phase change enthalpy, but also enhancing the photothermal conversion efficiency (up to 88.2%). There is also a new feature of precise regulation of the phase change temperatures, e.g., from 9.5 to 20.5 °C for the solidification temperature. More importantly, due to the strong confinement of PEG and Au NPs inside the CNT network, the composite fiber also shows excellent thermal stabilities, including the anti-leakage behavior and cycling phase change ability.

Transfer printing is an important material heterogeneous technique with unique capability for developing existing and envisioned electronic or optoelectronic systems. Here, a simple design of ultrasonic droplet stamp is reported featuring a water droplet on an acoustic resonator attached to a glass sheet, for developing an efficient non-contact transfer printing. The water droplet offers the benefits of a gentle and conformal contact, yielding an enough adhesion for a reliable pickup in the absence of ultrasound, and ejects a sub-droplet rapidly due to the Raleigh instability with the ultrasound for an easy non-contact printing. Experimental studies are carried out to investigate the transient response of ultrasonic droplet stamp under the action of ultrasound and showed that the proposed stamp exhibited extraordinary capabilities of damage-free pickup and receiver-independent printing. Demonstrations of the ultrasonic droplet stamp in transfer printing of thin inks with different materials and shapes onto various flat, curved and rough surfaces illustrate its great potential for heterogeneous integration and deterministic assembly.

Topological analysis is widely adopted in various research fields to unveil intricate features and structural relationships implied in geometrical objects. Especially, in the fields of data analysis, exploring the topological properties of various images offers rich insights into the intrinsic geometrical information within them. In this study, a novel approach is proposed to investigate the topological properties of arbitrary grayscale images by employing a straightforward procedure used in 2D magnetism studies to calculate topological numbers. This method utilizes machine learning techniques to transfer chiral magnetic textures onto the images. Then, the topological number is then computed directly from the converted images by integrating the solid angles formed by adjacent spin vectors. The method successfully identifies the topological numbers of various grayscale images, showing stable performances against small noises. Furthermore, two applications of the method: are demonstrated topological analysis of the Modified National Institute of Standards and Technology (MNIST) dataset and the counting of blood cells in microscopic images.

Ballistocardiography (BCG) studies ballistic forces on the body generated during a heartbeat. As it is an unobtrusive detection method, that requires sensors measuring small dynamic forces. Piezoelectric sensors are ideal, but improvements in sensitivity are needed. Here, a universal method is demonstrated to obtain enhanced effective transverse charge constants by utilizing thin and long sensors fabricated upon compliant substrates. This approach is validated using the uniquely printable and patternable piezoelectric polymer, poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE). Discrete sensors detect displacements of less than 1 µm, dynamic forces of ∼mN, and accelerations of ≈1 mm⁻¹ s². Since the sensor is screen-printable, it is upscaled to a human-sized array (60 × 90 cm, 255 sensors). High quality spatially resolved BCG measurements of a person is demonstrated in seated and supine positions. The obtained heart rate is verified using photoplethysmography. This development opens the door to ever-more sensitive piezoelectric sensors, crucial for applications including and beyond healthcare.

Tweezers based on optical, electric, magnetic, and acoustic fields have shown great potential for contactless object manipulation. However, current tweezers designed for manipulating millimeter-sized objects such as droplets, particles, and small animals exhibit limitations in translation resolution, range, and path complexity. Here, a novel acoustic vortex tweezers system is introduced, which leverages a unique airborne acoustic vortex end effector integrated with a three-degree-of-freedom (DoF) linear motion stage, for enabling contactless, multi-mode, programmable manipulation of millimeter-sized objects. The acoustic vortex end effector utilizes a cascaded circular acoustic array, which is portable and battery-powered, to generate an acoustic vortex with a ring-shaped energy pattern. The vortex applies acoustic radiation forces to trap and spin an object at its center, simultaneously protecting this object by repelling other materials away with its high-energy ring. Moreover, The vortex tweezers system facilitates contactless, multi-mode, programmable object surfing, as demonstrated in experiments involving trapping, repelling, and spinning particles, translating particles along complex paths, guiding particles around barriers, translating and rotating droplets containing zebrafish larvae, and merging droplets. With these capabilities, It is anticipated that the tweezers system will become a valuable tool for the automated, contactless handling of droplets, particles, and bio-samples in biomedical and biochemical research.

The opportunity to create magneto-responsive soft materials (MSMs) with in-process tailorable and locally controllable magnetic properties is highly desirable across many technological and biomedical applications. In this paper, this capability is demonstrated for the first time using computer-controlled dual-material aerosol jet printing (DMAJP) technology. This approach allows controlled variation of composition between the aerosols of a magnetic nanoparticles (MNPs) ink and a photocurable polymer during the printing process. The mixing ratio of the two aerosols determines the MNPs loading in the nanocomposite, which can be used to locally control the magnetic properties of the printed structures. The printing process is structured in a layer-by-layer fashion in combination with a sacrificial layer approach for building fully freestanding MSM structures that combine magnetoactive and non-magnetoactive elements in a single process multi-material printing method with no further assembly requirements. Using this method, the direct manufacturing of small-scale multi-material soft objects with complex shapes and programmable functions whose movements can be controlled by the application of an external magnetic field is demonstrated.

The demand for stretchable strain sensors with customizable sensitivities has increased across a spectrum of applications, spanning from human motion detection to plant growth monitoring. Nevertheless, a major challenge remains in the digital fabrication of scalable and cost-efficient strain sensors with tailored sensitivity to diverse demands. Currently, there is a lack of simple digital fabrication approaches capable of adjusting strain sensitivity in a controlled way with no changes to the material and without affecting the linearity. In this study, parallel microgates-based strain sensors whose strain sensitivity can be adjusted systematically throughout an all-laser-based fabrication process without any material replacement are presented. The technique employs a two-step direct laser writing method that combines the well-established capabilities of laser ablation and laser marking, boasting a varying gauge factor of up to 433% (GF  =  168), while paving the way for the mass production of nanocomposite strain sensors. Parallel microgates-based strain sensors exhibit a remarkable signal-to-noise ratio at ultralow strains (ɛ  =  0.001), rendering them ideal for monitoring the gradual growth of plants. As an application demonstration, the proposed sensors are deployed on tomato plants to capture their growth under varying planting conditions including hydroponic and soil mediums, as well as diverse irrigation regimens.