Ag/alginate nanofiber membrane for flexible electronic skin.

Flexible electronic skin has stimulated significant interest due to its widespread applications in the fields of human-machine interactivity, smart robots and health monitoring. As typical elements of electrical skin, the fabrication process of most pressure sensors combined nanomaterials and PDMS films are redundant, expensive and complicated, and their unknown biological toxicity could not be widely used in electronic skin. Hence, we report a novel, cost-effective and antibacterial approach to immobilizing silver nanoparticles into-electrospun Na-alginate nanofibers. Due to the unique role of carboxyl and hydroxyl groups in Na-alginate, the silver nanopaticles with 30 nm size in diameter were uniformly distributed inside and outside the alginate nanofibers, which obtained pressure sensor shows stable response, including an ultralow detection limited (1 pa) and high durability (>1000 cycles). Notably, the pressure sensor fabricated by these Ag/alginate nanofibers could not only follow human respiration but also accurately distinguish words like 'Nano' and 'Perfect' spoke by a tester. Interestingly, the pixelated sensor arrays based on these Ag/alginate nanofibers could monitor distribution of objects and reflect their weight by measuring the different current values. Moreover, these Ag/alginate nanofibers exhibit great antibacterial activity, implying the great potential application in artificial electronic skin.

Wideband slow light with ultralow dispersion in a W1 photonic crystal waveguide.

A dispersion tailoring scheme for obtaining slow light in a silicon-on-insulator W1-type photonic crystal waveguide, novel to our knowledge, is proposed in this paper. It is shown that, by simply shifting the first two rows of air holes adjacent to the waveguide to specific directions, slow light with large group-index, wideband, and low group-velocity dispersion can be realized. Defining a criterion of restricting the group-index variation within a ±0.8% range as a flattened region, we obtain the ultraflat slow light with bandwidths over 5.0, 4.0, 2.5, and 1.0 nm when keeping the group index at 38.0, 48.8, 65.2, and 100.4, respectively. Numerical simulations are performed utilizing the three-dimensional (3D) plane-wave expansion method and the 3D finite-difference time-domain method.

[New method for wave-plate orientation determination based on the shape of the modulated spectrum].

A new method for the determination of fast axis of wave-plate is introduced. Based on the principle of electro-optic phase compensation in the wave-plate phase measuring method, the relation between the polarization extinction system out-put signal and the modulating signal can be acquired through the composition of frequency fixed alternating voltage modulation signal. Through the analysis of this process with Jones matrix, the out-put signal was usually found to be the composition of fundamental frequency and second harmonic frequency, the composition signal reflects the axis information as well as the phase information of the wave-plate, and this phenomenon has never been noticed before. Through the analysis of this phenomenon, the transformation trends of the composed wave-form by rotating of wave-plates with different orientations were deduced, and through the observation of the transformation trend, one can easily distinguish the fast and slow axes of wave-plates with phase retardation > pi as well as those with phase retardation < pi, and their phenomena are reverse to each other.