Self-Powered Colorful Dynamic Electrowetting Display Systems Based on Triboelectricity.

Electrowetting displays (EWDs) based on microfluidics are highly sought after in the fields of electronic devices, smart homes, and information communication. However, the power supply of the EWD systems for visually engaging multi-color displays remains a big challenge. Herein, self-powered colorful dynamic display systems are developed by integrating the triboelectric nanogenerator (TENG) with the EWD device. The TENG is designed with a nanotube-patterned surface and can generate open-circuit voltages ranging from 30 to 295 V by controlling the contact area. The wetting property of the micro-droplet exhibits a response to the applied voltage, enabling the triboelectricity-triggered electrowetting-on-dielectric. Driven by the voltage of 160 V, the monochromatic EWD exhibits bright color switching from magenta to transparent with a pixel aperture ratio of 78%, and the recovery process can be rapidly completed. Furthermore, the self-powered colorful dynamic EWD system can be achieved. By selectively applying the voltage to the pixels in the three monochromatic layers that constitute the colorful EWD, the wetting properties of the fluids can be controlled, allowing for colorful dynamic display. This work contributes to the advancement of color display technology for portable and wearable electronic ink displays, indoor and outdoor sports equipment, and information communication.

Phase-Transformation Nanoparticles Synchronously Boosting Mechanical and Electromagnetic Performance of SiBCN Ceramics.

Precursor-derived silicoboron carbonitride ceramic (PDC-SiBCN) has attracted significant attention as an advanced electromagnetic (EM) wave-absorbing material. However, the inherent porous and brittle characteristics limit its application as a structural load component in an EM interference environment. In this study, phase-transformation HfO2 nanoparticles were incorporated into PDC-SiBCN to reduce volume shrinkage, improve bonding interactions, and control structural defects, simultaneously boosting the plastic deformation and EM performance of brittle ceramics. The obtained HfO2/SiBCN ceramic showed enhanced flexural strength of up to 430.1% compared with that of the pure SiBCN ceramic. Furthermore, the HfO2/SiBCN ceramic also demonstrated excellent high-temperature EM absorption. The minimum reflection coefficient (RCmin) could reach -45.26 dB, and the effective absorption bandwidth (EAB) covered 2.80 GHz of the X band at 2.28 mm thickness at room temperature. Furthermore, the RCmin can still reach -44.83 dB, and the EAB can cover 2.4 GHz at 1.58 mm even at 1073 K. This work shows that phase-transformation nanoparticles could simultaneously improve the deformation ability and EM wave absorption properties of SiBCN ceramics. The results could guide the design and preparation of PDCs with strong carrying capacity and excellent EM absorption, even in harsh environments.

A phonic Braille recognition system based on a self-powered sensor with self-healing ability, temperature resistance, and stretchability.

Braille recognition is of great significance for the visually impaired and blind people to achieve convenient communication and learning. A self-powered Braille recognition sensing system with long-term survivability and phonic function could provide those people with greatly enhanced access to information and thus improve their living quality. Herein, we develop a skin-like self-powered Braille recognition sensor with self-healing, temperature-resistant and stretchable properties, which is further connected with the designed audio system to realize real-time conversion from mechanical stimulus to electrical signals and then to audio signals. The sensor is fabricated using dynamic interaction-based self-healing materials, which constitute an imine bond-based cross-linked polymer for the triboelectric layer and a hydrogen bond-based organohydrogel for the electrode layer. Moreover, the conductive organohydrogel-based electrode is provided with stretchable, anti-freezing, and non-drying properties. Consequently, minimized impact on the output performance of the sensor is found under mechanical impact, harsh environments and large deformation, enabling a long lifespan, high durability, and good stability. The self-powered sensor can be applied in a Braille recognition system, in which the Braille characters can be further decoded and read out. This work shows a reliable and flexible device with promising prospects in information technology.

Highly Stretchable, Self-Healable, Ultrasensitive Strain and Proximity Sensors Based on Skin-Inspired Conductive Film for Human Motion Monitoring.

Recently, flexible electronics have been paid great attention due to their unique characteristics, such as high stretchability, arbitrary bending, and recoverable deformation. As a core component, flexible conductive materials with skin-like properties are desirable and valuable for the development of flexible electronics. However, the integration of skin-like mechanical properties, inherent self-healing ability, ultrahigh sensitivity, and electrical conductivity into one material is difficult to be realized. Here, this study reports a kind of conductive film (PAM-dc-fGO) fabricated by cross-linking intrinsic self-repair polyazomethine (PAM) and ethylenediamine-functionalized graphene oxide (fGO) through dynamic covalent bonds (imine bonds, -CH═N-). The as-prepared conductive films exhibit skin-like mechanical properties with a stretchability of 212-275% and elastic moduli of 0.76-4.23 MPa. In addition, the healing efficiency in mechanical properties of the 24 h healed specimen can restore up to 99%, and the healing efficiency in terms of electrical conductivity still maintains above 95% after five breaking/healing cycles, indicating an excellent capability of self-repair. Due to the ultrahigh sensing sensitivity with the gauge factor (GF) of 641, the PAM-dc-fGO film-based strain sensor can precisely detect the weak signals from the human body. Moreover, the remote monitoring of human motions with a long distance of about 100 cm has been successfully conducted by a PAM-dc-fGO proximity sensor. This work provides a new path for the development of multifunctional soft materials, and the sensors show great potential in health diagnoses and security protection applications.

A flexible topo-optical sensing technology with ultra-high contrast.

Elastic folding, a phenomenon widely existing in nature, has attracted great interests to understand the math and physical science behind the topological transition on surface, thus can be used to create frontier engineering solutions. Here, we propose a topo-optical sensing strategy with ultra-high contrast by programming surface folds on targeted area with a thin optical indicator layer. A robust and precise signal generation can be achieved under mechanical compressive strains (>0.4). This approach bridges the gap in current mechano-responsive luminescence mechanism, by utilizing the unwanted oxygen quenching effect of Iridium-III (Ir-III) fluorophores to enable an ultra-high contrast signal. Moreover, this technology hosts a rich set of attractive features such as high strain sensing, encoded logic function, direct visualisation and good adaptivity to the local curvature, from which we hope it will enable new opportunities for designing next generation flexible/wearable devices.

Antisolvent-assisted controllable growth of fullerene single crystal microwires for organic field effect transistors and photodetectors.

There are only a few reported methods by which the size and morphology of organic single crystals for high-performance organic field-effect transistors (OFETs) or other devices can be controlled. Here, a facile solution-processed antisolvent vapor diffusion method was employed to grow millimeter-length C60 single crystal microwires directly in solution. The size of the microwires can be controllably varied via the C60 concentration and/or the choice of antisolvent. OFETs fabricated from the as-produced microwires exhibit mobilities as high as 2.30 cm2 V-1 s-1. A clear relationship between the crystal preparation conditions and device performance is revealed whereby it is observed that the lower the evaporation rate of antisolvent and/or the higher the C60 concentration, the higher the device performance. Photodetectors based on our microwires give a responsivity that is an order of magnitude higher than those grown by drop-casting methods. This study provides a facile method for the crystal engineering of size-tunable millimeter-length C60 single crystals, and revealed the important influences of the antisolvent on the C60 crystal size and the performance of devices based on them. We believe that our processing approach can be further exploited for a broad range of other organic semiconductors to achieve desirable single crystal size and morphology and thus obtain desirable OFETs and photodetector performance.

Acid-Cleavable Unimolecular Micelles from Amphiphilic Star Copolymers for Triggered Release of Anticancer Drugs.

In this contribution, amphiphilic star copolymers (H40-star-PCL-a-PEG) with an H40 hyperbranched polyester core and poly(ε-caprolactone)-a-poly(ethylene glycol) copolymer arms linked with acetal groups are synthesized using ring-opening polymerization and a copper (I)-catalyzed alkyne-azide cycloaddition click reaction. The acid-cleavable acetal groups between the hydrophilic and hydrophobic segments of the arms endow the amphiphilic star copolymers with pH responsiveness. In aqueous solution, unimolecular micelles can be formed with good stability and a unique acid degradability, as is desirable for anticancer drug carriers. For the model drug of doxorubicin, the in vitro release behavior, intracellular release, and inhibition of proliferation of HeLa cells show that the acid-cleavable unimolecular micelles with anticancer activity can be dissociated in an acidic environment and efficiently internalized by HeLa cells. Due to the acid-cleavable and biodegradable nature, unimolecular micelles from amphiphilic star copolymers are promising for applications in intracellular drug delivery for cancer chemotherapy.

Antifungal activity of chitooligosaccharides against the dermatophyte Trichophyton rubrum.

Antifungal activity against the dermatophytic fungus Trichophyton rubrum by a well-characterized chitooligosaccharides (COS) sample, hydrolyzed using a recombinant chitosanase, was investigated in vitro and in vivo. The minimum inhibitory concentration (MIC) of COS ranged between 0.25 and 0.50%, which was measured using a microdilution method. Analysis of inhibition rates using an agar diffusion method showed that treatment with 0.5% and 1% COS significantly suppressed T. rubrum cell growth (p<0.05 and p<0.01, respectively, in comparison with untreated control). Morphological changes and structural alterations of cells were observed by TEM. In vivo efficacy of COS in treatment of T. rubrum dermatophytosis was evaluated using a guinea pig model. Skin lesion scores revealed a strong, dose-dependent therapeutic effect of COS. The 5% COS group showed a reduction of skin lesions even greater than that of the positive control group treated with 1% fluconazole (FCZ). Histological analysis revealed no inflammation or tissue destruction in the groups treated with 5% COS or 1% FCZ. Hyperkeratosis was also observed, perhaps resulting from a defensive response of the tissue cells to COS. The findings indicate that COS has excellent potential for development of novel antifungal drugs for clinical treatment/remission of dermatophytoses.