crucial for water droplets to move along the leaf veins and fi nally to the root, helping the plants to survive. It is recognized that the quasi-1D arrangement of micropapilla ( ≈ 5 μ m) covered with nanoscale surface features, namely a micro-and nano-, two-level hierarchical structure, leads to the observed anisotropic wetting. Inspired by this natural phenomenon, artifi cial anisotropic surfaces that mimic the quasi-1D microstructures of a rice leaf have attracted great attention for their important potential applications in fl uidic control, water-directional transportation, and so on. [ 5 , 6 ] A variety of technologies [7][8][9][10][11][12][13] such as photolithography, [ 7 , 8 ] surface wrinkling, [ 9 ] electrospinning, [ 10 ] and interference lithography [ 11 , 12 ] has been used to reproduce the biomimetic surfaces. Specifi cally, the smaller (width 0.3-20 μ m and height 0.05-5 μ m) groove arrays [ 7 , 9-12 , 13 a-d] have been widely prepared to mimic the quasi-1D microstructures of the rice leaf and have become the most common microstructures used for investigating anisotropic wetting properties. For example, Morita et al. [ 7 ] reported macroscopic anisotropic wetting on line-patterned surfaces prepared by vacuum-UV lithography, Zhao et al. [ 11 a] prepared anisotropic sub-micrometric periodic groove arrays on azobenzene-containing multiarm starpolymer fi lms, and Xia et al. [ 12 a] realized strongly anisotropic wetting on nanopatterned surfaces by multibeam-laser interference. Anisotropic contact angles from 5 o to 79 o have been successfully produced by designing different groove arrays, leading to great progress in the reproduction of the rice-leaf structure. Nevertheless, until now, the excellent anisotropic-sliding ability ( ≈ 3 o /9 o ) of the rice leaf, the most important expected function, has not been realized. Moreover, precise control of the anisotropic-sliding behavior remains challenging, possibly the direct result of insuffi cient understanding of the physical mechanism of anisotropic sliding. An apparent example is that artifi cial surfaces reported so far have focused on single-level groove arrays with of smaller size, which suffer from low contact angle (CA) so that the water droplet in Wenzel's state cannot freely roll. In addition, the technical challenge of characterizing anisotropic-dynamic behavior hinders deep insight into the underlying physics of anisotropic sliding. In detail, static CAs along the parallel and perpendicular directions of one surface are generally used to depict anisotropy because the water droplet is in the pinned state with a small contact angle. [7][8][9][10][11][12] However, for anisotropic surfaces with excellent superhydrophobicity (CA larger than 150 o ), it is insuffi cient to evaluate the anisotropic wetting by using CAs. In this case, the sliding angle Rice leaves with anisotropic sliding properties have the ability to directionally control the movement of water microdroplets. However, the realization of artifi cial anisotropic sliding biosurfa...

A simple seed-mediated growth route is developed to fabricate monodisperse, uniform superparamagnetic Fe(3)O(4) core/gold shell structured nanocomposites with tunable sizes and optical properties, in which gold seed formation and attachment onto the core surface via S-Au covalent bonding proceeds almost simultaneously in the one-pot synthesis. The as-prepared nanocomposite is demonstrated to have a great potential for magnetic resonance imaging (MRI)-guided, focused photothermal tumor therapy under near-IR laser radiation.

Artifi cial superhydrophobic surfaces [1][2][3][4][5][6][7][8][9][10] with water contact angles (CAs) greater than 150 ° have been intensively investigated due to their unique "anti-water" property that could be utilized in a wide range of applications. [11][12][13] Recent development of intelligent devices, such as microfl uidic switches and biomedicine transporters, makes strong demands on surface wettability control, therefore, responsive surfaces have become a signifi cant issue for superhydrophobic studies. Up to now, various smart surfaces have been successfully developed as reversible switches for wettability control through a micronanostructured surface on a responsive material. [14][15][16][17][18][19][20][21][22][23][24][25] These unique tunings of surface wettability greatly contributed to refi ned control of surface wettability. With the thorough understanding of superhydrophobic phenomenon, superhydrophobic surfaces have been classifi ed into fi ve states [ 26 ] according to the details of CA hysteresis, which have been well verifi ed on different samples based on experimental results. [ 1 , 8 , 27-29 ] Superhydrophobic surfaces in different states show distinctive advantages in varied applications. Hence, efforts have also been devoted to precise tuning between different superhydrophobic states. For example, Lai et al. [ 23 a] investigated superhydrophobic surfaces with controlled adhesion to water droplets by using different kinds of rough surfaces. Li et al. [ 23 b] observed reversible switching between a transitional state (sliding angle of 75 ° ) and the Wenzel superhydrophobic state (high adhesion force) by changing the temperature. This inspired no-loss microdroplet transfer and trace-liquid reactor applications, [ 15 ] which usually need precise control of water droplet movement on the same surface from "roll-down" to "pinned" superhydrophobic states. Nevertheless, this no-loss transfer of a given water droplet requires a sensitive in situ tuning of surface wettability. Jiang et al. have reported an in situ control of magnetic droplet movement using extra magnetic fi eld, where the tuning was based not on pure water droplets, but on magnetic liquids. [ 27 ] From the practical point of view, it is still worth pointing out that the above-mentioned tuning approaches usually depend on harsh tuning conditions, such as UV irradiation, [ 18 ] electrical current, [ 19 , 21 ] a wide range of temperature, [ 23 ] or treatments by chemical solvents. [ 22 , 25 ] They may be not suitable for mild condition applications. For example, enzymes or biological cells in microfl uidic devices would be seriously affected under UV irradiation, temperature change, or addition of chemical substances. In addition, most of these tunable surfaces are based on artifi cially introduced material compositions or particular material species, [18][19][20][21][22][23][24][25] such as azobenzene and metal oxides, which suffer from poor biocompatibility. Therefore, it is urgently desirable to fi nd a simple, environmentally...

Femtosecond lasers have unique characteristics of ultrashort pulse width and extremely high peak intensity; however, one of the most important features of femtosecond laser processing is that strong absorption can be induced only at the focus position inside transparent materials due to nonlinear multiphoton absorption. This exclusive feature makes it possible to directly fabricate three-dimensional (3D) microfluidic devices in glass microchips by two methods: 3D internal modification using direct femtosecond laser writing followed by chemical wet etching (femtosecond laser-assisted etching, FLAE) and direct ablation of glass in water (water-assisted femtosecond laser drilling, WAFLD). Direct femtosecond laser writing also enables the integration of micromechanical, microelectronic, and microoptical components into the 3D microfluidic devices without stacking or bonding substrates. This paper gives a comprehensive review on the state-of-the-art femtosecond laser 3D micromachining for the fabrication of microfluidic, optofluidic, and electrofluidic devices. A new strategy (hybrid femtosecond laser processing) is also presented, in which FLAE is combined with femtosecond laser two-photon polymerization to realize a new type of biochip termed the ship-in-a-bottle biochip.

Closed-packed high numerical aperture (NA) microlens arrays (MLA) are highly desirable for high resolution imaging and high signal-to-noise-ratio detection in micro-optical and integrated optical applications. However, realization of such devices remains technically challenging. Here, we report high quality fabrication of curved surfaces and MLAs by taking the full advantage of surface self-smoothing effect by creating highly reproducible voxels and by adopting an equal-arc scanning strategy. MLA of approximately 100% fill ratio and NA of 0.46, much greater than those ever reported, 0.13, is demonstrated, whose excellent optical performance was approved by the sharp focusing and high resolution imaging.

Lactic acid is an important platform molecule in the synthesis of a wide range of chemicals. However, in aqueous solutions without alkali, its efficient preparation via the direct catalysis of sugars is hindered by a side dehydration reaction to 5-hydroxymethylfurfural due to Brønsted acid, which originates from organic acids. Herein, we report that a previously unappreciated combination of common two metal mixed catalyst (Zn-Sn-Beta) prepared via solid-state ion exchange synergistically promoted this reaction. In water without a base, a conversion exceeding 99% for sucrose with a lactic acid yield of 54% was achieved within 2 hours at 190 °C under ambient air pressure. Studies of the acid and base properties of the Zn-Sn-Beta zeolite suggest that the introduction of Zn into the Sn-Beta zeolite sequentially enhanced both the Lewis acid and base sites, and the base sites inhibited a series of side reactions related to fructose dehydration to 5-hydroxymethylfurfural and its subsequent decomposition.

Composition modification and surface microstructures have been widely utilized in interface science to improve the surface performance. In this paper, we observed a significant improvement of oil contact angle (CA) from 66 ± 2° to 120 ± 4° by introducing a radical silanol group on a flat PDMS surface through oxygen plasma pretreatment. By combining surface microstructures and plasma modification, we produced three kinds of superoleophobic surfaces: 20 μm pitch micropillar arrays, 2.5 μm pitch micropillar arrays and gecko foot-like hierarchical microstructures. Among them, the hierarchical surface with high surface roughness showed extreme underwater superoleophobicity, which featured ultrahigh CA (175 ± 3°) and ultrasmall sliding angle (<1°). Quantitative measurements demonstrated that these superoleophobic surfaces exhibited distinct adhesive behaviors, by which they were interpreted as Wenzel's, Cassie's and the Lotus state, respectively. A microfluidic channel with superoleophobic microstructures was further created by novel curve-assisted imprint lithography, and the characterization based on anti-oil contamination applications was carried out and discussed. We believe that the superoleophobic surfaces will power broad applications in oil microdroplet transportation, anti-oil channels and droplet microfluidic systems.

True three-dimensionally (3D) integrated biochips are crucial for realizing high performance biochemical analysis and cell engineering, which remain ultimate challenges. In this paper, a new method termed hybrid femtosecond laser microfabrication which consists of successive subtractive (femtosecond laser-assisted wet etching of glass) and additive (two-photon polymerization of polymer) 3D microprocessing was proposed for realizing 3D "ship-in-a-bottle" microchip. Such novel microchips were fabricated by integrating various 3D polymer micro/nanostructures into flexible 3D glass microfluidic channels. The high quality of microchips was ensured by quantitatively investigating the experimental processes containing "line-to-line" scanning mode, improved annealing temperature (645°C), increased prebaking time (18 h for 1mm-length channel), optimal laser power (1.9 times larger than that on the surface) and longer developing time (6 times larger). The ship-in-a-bottle biochips show high capabilities to provide simultaneous filtering and mixing with 87% efficiency in a shorter distance and on-chip synthesis of ZnO microflower particles.