Molecular self-assembly is the spontaneous association of molecules under equilibrium conditions into stable, structurally well-defined aggregates joined by noncovalent bonds. Molecular self-assembly is ubiquitous in biological systems and underlies the formation of a wide variety of complex biological structures. Understanding self-assembly and the associated noncovalent interactions that connect complementary interacting molecular surfaces in biological aggregates is a central concern in structural biochemistry. Self-assembly is also emerging as a new strategy in chemical synthesis, with the potential of generating nonbiological structures with dimensions of 1 to 10(2) nanometers (with molecular weights of 10(4) to 10(10) daltons). Structures in the upper part of this range of sizes are presently inaccessible through chemical synthesis, and the ability to prepare them would open a route to structures comparable in size (and perhaps complementary in function) to those that can be prepared by microlithography and other techniques of microfabrication.

Molecular self-assembly and nanochemistry: A chemical strategy for the synthesis of nanostructures

Recent developments of zinc oxide based photocatalyst in water treatment technology: A review

Mechanosensation electronics (or Electronic skin, e-skin) consists of mechanically flexible and stretchable sensor networks that can detect and quantify various stimuli to mimic the human somatosensory system, with the sensations of touch, heat/cold, and pain in skin through various sensory receptors and neural pathways. Here we present a skin-inspired highly stretchable and conformable matrix network (SCMN) that successfully expands the e-skin sensing functionality including but not limited to temperature, in-plane strain, humidity, light, magnetic field, pressure, and proximity. The actualized specific expandable sensor units integrated on a structured polyimide network, potentially in three-dimensional (3D) integration scheme, can also fulfill simultaneous multi-stimulus sensing and achieve an adjustable sensing range and large-area expandability. We further construct a personalized intelligent prosthesis and demonstrate its use in real-time spatial pressure mapping and temperature estimation. Looking forward, this SCMN has broader applications in humanoid robotics, new prosthetics, human-machine interfaces, and health-monitoring technologies.

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Skin-inspired highly stretchable and conformable matrix networks for multifunctional sensing

New concept ultraviolet photodetectors

Introduction to Surface Chemistry and Catalysis

Ultraviolet (UV) photodetection has drawn a great deal of attention in recent years due to a wide range of civil and military applications. Because of its wide band gap, low cost, strong radiation hardness and high chemical stability, ZnO are regarded as one of the most promising candidates for UV photodetectors. Additionally, doping in ZnO with Mg elements can adjust the bandgap largely and make it feasible to prepare UV photodetectors with different cut-off wavelengths. ZnO-based photoconductors, Schottky photodiodes, metal–semiconductor–metal photodiodes and p–n junction photodetectors have been developed. In this work, it mainly focuses on the ZnO and ZnMgO films photodetectors. We analyze the performance of ZnO-based photodetectors, discussing recent achievements, and comparing the characteristics of the various photodetector structures developed to date.

https://www.mdpi.com/1424-8220/10/9/8604/pdf

ZnO-Based Ultraviolet Photodetectors

ZnO nanowire photodetectors with and without Au nanoparticles have been fabricated and investigated. The dark current decreases by 2 orders of magnitude and the ratio of photo current to dark current increases after covering with Au nanoparticles. Meanwhile, the decorated Au nanoparticles can drastically improve the response speed of ZnO nanowire photodetectors. A physical model based on band energy theory was developed to illustrate the origin of the improvement of performance for ZnO nanowire photodetector attached with Au. Our work suggests that rational integration of ZnO wire and metal nanoparticles is a viable approach to improving the performance of ZnO nanowire photodetectors, which may help to advance optoelectronic devices.

Giant Improvement of the Performance of ZnO Nanowire Photodetectors by Au Nanoparticles

Scanning tunneling microscope (STM) induced light emission from artificial atomic scale structures comprising silicon dangling bonds on hydrogen-terminated Si(001) surfaces has been mapped spatially and analyzed spectroscopically in the visible spectral range. The light emission is based on a novel mechanism involving optical transitions between a tip state and localized states on the sample surface. The wavelength of the photons can be changed by the bias voltage of the STM. The spatial resolution of the photon maps is as good as that of STM topographic images and the photons are emitted from a quasipoint source with a spatial extension similar to the size of a dangling bond.

/pdf/visible-light-emission-from-atomic-scale-patterns-fabricated-500etybuhk.pdf

Visible light emission from atomic scale patterns fabricated by the scanning tunneling microscope

Owing to the special properties and wide applications, UV photodetectors based on wide-band-gap semiconductors have drawn an increasing interest during the last two decades. However, practical UV photodetectors are required two contradictory performances: high internal gain and fast recovery speed, because high internal gain is achieved by long life time of photoexcited carriers and fast recovery needs their fast decay. Their slow decay in wide-band-gap semiconductors has been known as a persistent photoconductivity (PPC) problem and hinders applications. In this paper, a good solution to the above contradictory problem is demonstrated on a single SnO2 microrod photoconductor, which shows both high photoconductive gain (≈1.5 × 109) and quick recovery speed ( 1 d), which is induced by a novel “reset” process: bending and straightening the microrod and subsequently applying a voltage pulse. This result suggests that SnO2 microrods have potential applications in high-performance UV photodetecting devices.

Ultrahigh-Gain Single SnO2 Microrod Photoconductor on Flexible Substrate with Fast Recovery Speed

Fabrication of protein–inorganic hybrid materials of innumerable hierarchical patterns plays a major role in the development of multifunctional advanced materials with their improved features in synergistic way. However, effective fabrication and applications of the hybrid structures is limited due to the difficulty in control and production cost. Here, we report the controlled fabrication of complex hybrid flowers with hierarchical porosity through a green and facile coprecipitation method by using industrial waste natural silk protein sericin. The large surface areas and porosity of the microsize hybrid flowers enable water purification through adsorption of different heavy metal ions. The high adsorption capacity depends on their morphology, which is changed largely by sericin concentration in their fabrication. Superior adsorption and greater selectivity of the Pb(II) ions have been confirmed by the characteristic growth of needle-shaped nanowires on the hierarchical surface of the hybrid flowers. The...

Controlled Fabrication of Silk Protein Sericin Mediated Hierarchical Hybrid Flowers and Their Excellent Adsorption Capability of Heavy Metal Ions of Pb(II), Cd(II) and Hg(II)

Makoto Sakurai

Papers

ZnO-Based Ultraviolet Photodetectors

Giant Improvement of the Performance of ZnO Nanowire Photodetectors by Au Nanoparticles

Visible light emission from atomic scale patterns fabricated by the scanning tunneling microscope

Ultrahigh-Gain Single SnO2 Microrod Photoconductor on Flexible Substrate with Fast Recovery Speed

Controlled Fabrication of Silk Protein Sericin Mediated Hierarchical Hybrid Flowers and Their Excellent Adsorption Capability of Heavy Metal Ions of Pb(II), Cd(II) and Hg(II)