Jun Liu

Microneedling has found various applications in dermatology recently. However, many problems still need to be solved in the fabrication of high-aspect-ratio polymeric microneedles with good mechanical strength, dimensional accuracy and thermal conductivity for energy-assisted treatments. Herein, a low-shrinkage photocurable resin specifically designed for high-precision additive manufacturing was developed in this work to enable the rapid and reproducible fabrication of ultra-long microneedle arrays through photopolymerisation-based 3D printing. Moreover, an even and uninterrupted layer of silver was added to the surface at room temperature via electroless plating. The resulting microneedle arrays have good structural integrity and high mechanical strength, and the thermal conductivity of them has been increased by a factor of 37 compared to that of uncoated polymeric materials. Mechanical tests showed that the compressive strength was high enough, and simulated skin and ex vivo porcine skin penetration experiments also demonstrated a low insertion force and stable microchannel formation. The in vitro cytotoxicity tests showed good cell compatibility both before and after silver coating. Such work has successfully developed an all-purpose and manufacturable microneedle platform that connects high-precision additive manufacturing with energy-based dermatological therapy, which provided a scalable strategy for expanding the application of polymeric microneedles in medical aesthetics and related clinical fields. The complete route from the digital model to the finished silver-coated array takes about 2.5 h and requires no mould, master or dedicated tooling. The arrays are intended to serve as low-cost, single-use and geometrically customisable needle-electrode cartridges for energy-assisted dermatological treatment and in particular for fractional radiofrequency (RF) microneedling.

Additively manufactured resin molds are susceptible to thermomechanical failure and accumulated damage during molding processes, severely limiting their service life. To address this, a thermally stable self-healing photocurable resin was developed for liquid crystal display (LCD) 3D printing. Microcapsules (MCs) comprising a commercial E51-grade epoxy resin core and a melamine–urea–formaldehyde (MUF) shell were incorporated into the photocurable matrix together with an amine curing agent to enable crack repair. At 7 wt % MCs, the optimized formulation showed a healing efficiency of 68.97% after healing at 60 °C for 12 h. It exhibited a 5% mass-loss temperature of 372.1 °C, a maximum mass-loss-rate temperature of 428.1 °C, and short-term shape retention after treatment at 240 °C for 4 h. Open-ended internal channels were fabricated and demonstrated room-temperature flow connectivity. Representative molds were further printed and used for silicone molding, demonstrating the potential of the optimized formulation for repairable LCD-printed resin molds requiring short-term heat resistance.

Among additive manufacturing techniques, vat photopolymerization (VPP) enables high‐resolution fabrication but remains limited by slow layer‐by‐layer processing. Although continuous liquid interface production (CLIP) eliminates platform retraction by creating an oxygen‐permeable dead zone, it still relies on discrete vertical lifts and costly membranes. Here, we present a continuous and uninterrupted 3D printing strategy that achieves high‐resolution fabrication at a very high speed up to 360 mm h ⁻¹ , even on LCD devices with only a weak UV illumination of 3 mW cm ⁻² . This strategy only involves a common high rigidity release film and low‐surface‐energy resins, which can effectively reduce interfacial deformation and separation forces to enable the build platform to lift continuously at a high speed. These print speeds allow parts to be produced in several minutes instead of hours.

Aqueous Zn-ion batteries promise safe, low-cost storage but are constrained by the coupled penalties of slow Zn2+ interfacial transfer and structural degradation in layered vanadium cathodes. Here we engineer a sequential hybrid architecture in which Ca2+ pillarization stabilizes and widens the V–O galleries, while an ultrathin polypyrrole (PPy) skin establishes a percolating electronic network and a chemically active interface. The Ca2+-reinforced host mitigates collapse during deep (de)insertion and reduces electrostatic trapping of Zn2+, whereas PPy lowers the desolvation/charge-transfer resistance and suppresses vanadium dissolution. Combined electrochemical analysis and multiscale characterizations reveal a shift toward faster interfacial redox and enhanced Zn2+ diffusivity. The optimized CaVO@PPy cathode delivers outstanding electrochemical performance and stability, achieving a high specific capacity of 478 mA h g-1 at 0.1 A g-1 and retaining 92% of its capacity after 1,000 cycles at 5 A g-1. This work illustrates how polymer interfaces, when coupled to inorganic pillarization, can re-balance kinetics and stability in aqueous multivalent cathodes.

Laser-cladding directed energy deposition enables both the repair and fabrication of complex metallic components with curved surfaces. However, during multi-axis deposition on curved substrates, sharp transient feed-rate fluctuations at corner segments—together with an approximately constant powder feed rate—readily cause local over-deposition and geometric defects (e.g., nodules and humps). These defects compromise surface-profile fidelity, thereby creating a major barrier to practical deployment. To overcome this limitation, we propose a corner-oriented path-optimization strategy based on geometric code parsing. By operating directly on the toolpath without modifying the Computer-Aided Design model or slicing workflow, the proposed method suppresses corner overbuild and associated morphological distortion in curved-surface directed energy deposition, substantially improving dimensional consistency and surface quality. Overall, this strategy provides a scalable and broadly applicable route toward high-precision, high-reliability, industrial-scale curved-surface additive manufacturing.

This paper investigates the impact of different charging methods on battery lifespan. Through theoretical analysis and mathematical derivation, a power function-based battery capacity degradation model K(I) = PI ^C is established, and the performance differences between constant-current charging (CC) and linear tapered-current charging (TC) strategies under different exponent C values are compared. The study finds that when C > 1, constant-current charging results in smaller capacity loss; when 0 < C < 1, tapered-current charging is more advantageous; and when C = 1, the two strategies are equivalent. A piecewise charging strategy is further proposed, dynamically selecting charging modes based on the fitting exponent C _i of current intervals. An Arduino-based piecewise charging control program is designed to regulate current via PWM signals, optimizing battery degradation under constant average current. Experimental results show that reasonable selection of the charging slope can effectively reduce the battery degradation rate and improve charging efficiency.

W-Cu composites are widely used in the fields of switch contact materials and electronic packages because of their high hardness, high plasticity, and excellent thermal conductivity, while the traditional W-Cu composite preparation process is often accompanied by problems such as a long production cycle, difficulties in the processing of shaped parts, and difficulties in guaranteeing the uniformity. Therefore, this work developed a chemical plating technique to prepare W-20 wt.% Cu composite powder with a core–shell structure and used this powder as a raw material for powder metallurgy to solve the problem of inhomogeneity in the production of W-Cu composite by the conventional solution infiltration method. Moreover, the work also developed a high-temperature-resistant photosensitive resin, which was used as a raw material to prepare injection molds using photocuring to replace traditional steel molds. Compared to steel molds, which take about a month to prepare, 3D printed plastic molds take only a few hours, greatly reducing the production cycle. At the same time, 3D printing also provides the feasibility of the production of shaped parts. The injection molded blanks were degreased and sintered under different sintering conditions. The results show that the resultant chemically plated W-Cu composite powder has a uniform Cu coating on the surface, and the Cu forms a dense and uniform three-dimensional network in the scanning electron microscope images of each subsequent sintered specimen, while the photocuring-prepared molds were used to prepare the W-Cu shaped parts, which greatly shortened the production cycle. This preparation method enables rapid preparation of tungsten–copper composite-shaped parts with good homogeneity.

Direct energy deposition (DED) technology shows promising applications in the production of roller die cutters. The optimization of process parameters, scanning strategies, and analyses of compressive properties and wear behavior are required prior to application. Therefore, this work investigated the influence of scanning strategy and overlap ratio on the microstructure, microhardness, compressive properties, and wear resistance of M2 high-speed steel (HSS) with DED on a 316 L cylindrical surface. The results reveal that along the deposition direction of the sample, the grain size gradually decreases, with hardness increasing from 187 HV in the matrix to 708 HV. As the overlap ratio increases, the grain size initially rises and then decreases, while hardness first declines and subsequently increases. The cross-scanning strategy effectively enhances the compressive strength by reducing porosity defects. Furthermore, the compressive strength of the samples initially increases with the overlap ratio before experiencing a slight decrease. The M-3 sample with a 50% overlap ratio exhibits the best compressive strength (3904 MPa). The wear rate decreases and then increases with the rising overlap ratio. Therefore, the M-3 sample, prepared using cross-scanning strategies with an overlap ratio of 50%, demonstrates a uniform and dense microstructure, resulting in superior wear resistance, and the wear rate is as low as 8 × 10⁻⁶ mm³·N⁻¹·m⁻¹. The current experimental results provide valuable references for the DED of die-cut knives.