Advanced Materials Technologies最新文献

Capacitive Touch Screens

In article number 2401029, Pegah Pezeshkpour and co-workers show a flexible capacitive touchscreen using silver nanowires as electrodes layers on polyimide. This technology is adapted to be used in Braille displays with ten dots-per-inch resolution developed for individuals with visual impairment. Using machine learning algorithms, a hand gesture recognition application is implemented with high detection accuracy.

Surface-enhanced Raman spectroscopy (SERS) is a powerful spectroscopic identification technique for analyzing chemical and biological analytes. Semiconductors are important materials that can expand the scope of SERS applications. However, the low SERS enhancements limit the application of semiconductor substrates. In this work, a new defect engineering approach is used, i.e., combining two types of defects, to enhance SERS performance by preparing of oxygen-vacancy-tunable W-doped VO₂ substrate. In this design, two types of defects effect in synergy to improve the SERS performance of rhodamine 6G (R6G). The oxygen vacancy concentration in W-doped VO₂ is adjusted through thermal annealing. This substrate achieves a detection limit of 1 × 10⁻⁷ m for R6G and an enhancement factor (EF) of 1.39 × 10⁶, comparable to noble metals. XPS and DFT analysis reveal that SERS enhancement can be attributed to the high density of electronic states associated with W-doping and oxygen vacancies. Additionally, W-doping increases the free electron concentration in the oxygen-deficient W-VO₂, which enhances the charge transfer (CT) between the substrate and R6G, leading to significant amplification of Raman signal. This work provides a defect-engineering approach based on the synergistic effect of oxygen vacancies and tungsten doping for enhancing the SERS performance of metal oxide semiconductor-based substrates.

Material Extrusion (MEX) 3D printing has been largely employed to process electrically conductive polymers to fabricate electronic components, which still suffer from bad performance due to high electrical resistance. The electroplating process is proven to drastically reduce the resistance by depositing a thin layer of copper on top of the electrically conductive polymer; however, this method comes with a price to pay: only external features can be plated with copper. The present research paper presents an innovative solution to overcome this issue by performing electroplating inside 3D-printed parts to plate internal layers (inaccessible for electroplating purposes with traditional approaches) with copper. Electroplating inside closed channels is performed: a remarkable reduction in electrical resistance of 5 orders of magnitude (from 2300 up to 0.08 Ω) is achieved in internal tracks. The proposed approach has also been implemented “on board” a commercial MEX machine to fabricate an assembly-free smart structure with a copper sensor completely embedded within dielectric material (improved performance compared to traditional counterpart). Furthermore, the proposed approach is proven to fully plate with copper not only planar tracks but also embedded 3D features such as coils. The present research unlocks the fabrication of assembly-free functional devices with embedded copper elements by only extruding polymers through MEX Additive Manufacturing.

Artificial lacrimal bypass tube (LBT) implantation has been widely used for treating proximal lacrimal drainage obstruction. However, its long-term clinical success is still constrained by the frequent tube dislodgement due to the mismatch mechanical properties to surrounding soft tissue and poor tissue fusion along its smooth surface. Aiming to tackle this challenge, here a method of 3D printing LBT is reported that comprises three key features: 1) mechanical adaptability to match with the characteristics of surrounding soft tissue, 2) tailorable surface porosity to promote tissue binding, and 3) customization to accommodate individual patient's anatomies. Using hydrogel-based biocompatible ink, LBTs are 3D printed that are initially rigid (compressive Young's moduli E: ≈1.6 GPa) for the ease of surgical insertion but become compliant (E: 0.16–3.36 MPa) after implantation to better match with the surrounding tissue. The inherent manufacturing flexibility of 3D printing enables integration of the LBT and porous shell to prompt tissue infusion to ensure its mechanical integrity. Ultimately, in vivo intramuscular and orthotopic implantation studies demonstrate that the LBTs exhibit excellent tolerance in rabbits with minimal inflammation observed, and the porous shells help to significantly reduce the dislocation rate from 80% to 13.3%.

Soft Actuators

The cover image showcases a dandelion-inspired artificial seed, which can float in the wind like a real dandelion seed, as detailed in article number 2400952 by Yixiong Feng, Xiuju Song, and co-workers. The close-up bubble at the bottom of the image displays the key component of the artificial seed: a stimuli-responsive actuator based on Ti₃C₂T_x MXene and polyethylene. The close-up bubble at the top highlights the MXene/PE soft actuator's ability to respond to six different types of stimuli, including humidity, light, high temperature, low temperature, applied voltage, and specific volatile organic compounds.

Wireless Acoustofluidics

In article number 2400572, Wujin Sun, Wei Zhou, Zhenhua Tian, and co-workers present wireless acoustofluidic chips that leverage wireless power transfer and frequency multiplexing to create programmable acoustic fields. These chips offer advanced capabilities for particle arrangement, cell alignment, fluid streaming, and microparticle enrichment, with potential applications in wearable sensors, implantable devices, and biomedical engineering.

Coplanar Edible Rechargeable Batteries

A riboflavin-quercetin edible rechargeable battery based on a new coplanar architecture with an increased capacity of 20 μAh is presented in article number 2400715 by Mario Caironi and co-workers. Its architecture favors multiple battery connections and interconnection with electronic components. The battery shows an operational stability of two weeks and stable performance between 0 °C and 37 °C, demonstrating its possible implementation in different low-power electronic applications.

Conducting Polymer Electrodes

In article number 2400849, Jadranka Travas-Sejdic, Peng Du, and co-workers demonstrate a wet-printing technique to fabricate stretchable conducting polymer electrodes. The electrodes remain strain-insensitive up large strain, resulting in superior signal quality compared to metal electrodes for in vivo recordings of gastric bioelectrical slow waves.

Vascular Grafts

In article number 2400224, Norbert Radacsi and co-workers use an innovative hybrid extrusion-printing and electrospinning technique to fabricate compliant vascular grafts. These grafts combine the strength of electrospun nanofibers with extrusion-printed hydrogels that can support cell growth. This method improves the mechanical properties of any hydrogel, offering a promising solution for bioprinting and advancing the field of regenerative medicine.