Wafer-Level Manufacturing of MEMS H Sensing Chips Based on Pd Nanoparticles Modified SnO Film Patterns.

In this manuscript, a simple method combining atomic layer deposition and magnetron sputtering is developed to fabricate high-performance Pd/SnO film patterns applied for micro-electro-mechanical systems (MEMS) H sensing chips. SnO film is first accurately deposited in the central areas of MEMS micro hotplate arrays by a mask-assistant method, leading the patterns with wafer-level high consistency in thickness. The grain size and density of Pd nanoparticles modified on the surface of the SnO film are further regulated to obtain an optimized sensing performance.

Review on recent progress in on-line monitoring technology for atmospheric pollution source emissions in China.

Emissions from mobile sources and stationary sources contribute to atmospheric pollution in China, and its components, which include ultrafine particles (UFPs), volatile organic compounds (VOCs), and other reactive gases, such as NH and NO, are the most harmful to human health. China has released various regulations and standards to address pollution from mobile and stationary sources. Thus, it is urgent to develop online monitoring technology for atmospheric pollution source emissions.

The Dehydrogenation of H-S Bond into Sulfur Species on Supported Pd Single Atoms Allows Highly Selective and Sensitive Hydrogen Sulfide Detection.

The supported metal catalysts on scaffolds usually reveal multiple active sites, resulting in the occurrence of side reaction and being detrimental to the achievement of highly consistent catalysis. Single atom catalysts (SACs), possessed with highly consistent single active sites, have great potentials for overcoming such issues. Herein, the authors used SACs to modulate kinetic process of gas sensitive reaction.

High-performance field-effect transistor glucose biosensors based on bimetallic Ni/Cu metal-organic frameworks.

Accurate detection of glucose is essential for the diagnosis of diabetes, wherein effective and sensitive biosensors for glucose detection are needed. Here, we fabricated a glucose sensor based on field-effect transistor (FET) with bimetallic nickel-copper metal-organic frameworks (Ni/Cu-MOFs) as its channel layers which were grown in-situ through a simple one-step hydrothermal method and modified with glucose oxidase (GOD) by using glutaraldehyde (GA) as linkers. Due to the synergistic effect of Ni ions and Cu ions in MOFs, the sensor (GOD-GA-Ni/Cu-MOFs-FET) showed good field effect performance and great responses to glucose through enzymatic reactions.

Au-Decorated ZnFeO Yolk-Shell Spheres for Trace Sensing of Chlorobenzene.

Noble metals supported on metal oxides are promising materials for widely applying on gas sensors because of their enviable physical and chemical properties in enhancing the sensitivity and selectivity. Herein, pristine ZFO yolk-shell spheres composed of ultrathin nanosheets and ultrasmall nanoparticles decorated with nanosized Au particles with a diameter of 1-2 nm are fabricated using the method of solution-phase deposition-precipitation. As a result, the Au@ZFO yolk-shell sphere based sensor exhibits significantly sensing performances for chlorobenzene (CB).

Improved SERS activity of non-stoichiometric copper sulfide nanostructures related to charge-transfer resonance.

The low enhancement factor of semiconductor SERS substrates is a major obstacle for their practical application. Therefore, there is a need to explore the facile synthesis of new SERS substrates and reveal the SERS enhancement mechanism. Here, we develop a simple, facile and low-cost two-step method to synthesize copper sulfide based nanostructures with different CuS contents.

Field-Effect Transistor Based on an in Situ Grown Metal-Organic Framework Film as a Liquid-Gated Sensing Device.

Ni(HITP), a novel and promising two-dimensional metal-organic framework (MOF) material, has been utilized in the areas of catalysis, sensing, and supercapacitors. It is very suitable for preparing field-effect transistor (FET) devices due to its good conductivity, porous structure, as well as easy film formation. Nevertheless, there is a challenge to transfer membrane materials undamaged to the substrates.

Pd-Catalyzed Reaction-Producing Intermediate S on a Pd/InO Surface: A Key To Achieve the Enhanced CS-Sensing Performances.

Although chemiresistive gas sensors, based on metal-oxide semiconductors, have exhibited particular promise for the monitoring of air pollution, they are often limited because of poor selectivity. In that case, to overcome this issue, according to the essence of the gas-sensing process, the method of reforming the surface reaction path on the surface of the sensing materials was used. Here, we report that Pd nanoparticles supported over the InO composites, featured with a yolk-shell structure, enable the trace detection of carbon disulfide (CS) gas molecules, which are immensely dangerous to humans and animals.

Facile Synthesis of the Composites of Polyaniline and TiO₂ Nanoparticles Using Self-Assembly Method and Their Application in Gas Sensing.

The composites of polyaniline and TiO₂ nanoparticles with different contents were prepared in the aqueous solution of phosphoric acid, in which the phosphoric acid was selected as the protonic acid to improve the conductivity of polyaniline. In the composites, the TiO₂ nanoparticles with the size of about 20 nm were coated by a layer of polyaniline film with a thickness of about 5 nm. Then, the gas sensors were constructed by a liquid⁻gas interfacial self-assembly method.

Self-Assembly of CuO Monolayer Colloidal Particle Film Allows the Fabrication of CuO Sensor with Superselectivity for Hydrogen Sulfide.

CuO monolayer colloidal particle films with controllable thickness and homogeneous microstructure were prepared by self-assembly and subsequent calcination based on CuO colloidal particles. Large-scale CuO monolayer colloidal particle films have the particle size of 300-500 nm, and CuO colloidal particles are hollow. It was found that such a structure exhibits excellent room-temperature HS-gas-sensing properties.

The Fabrication of Au@C Core/Shell Nanoparticles by Laser Ablation in Solutions and Their Enhancements to a Gas Sensor.

A convenient and flexible route is presented to fabricate gold noble metal nanoparticles wrapped with a controllable ultrathin carbon layer (Au@C) in one step based on laser ablation of the noble metal targets in toluene-ethanol mixed solutions. The obtained metal nanoparticles were <20 nm in size after ablation, and the thickness of the wrapped ultrathin carbon layer was 2 nm in a typical reaction. The size of the inner noble metal nanoparticles could be controlled by adjusting the power of laser ablation, and the thickness of the ultrathin carbon layer can be controlled from 0.

Ultrafine Pt NPs-Decorated SnO/α-FeO Hollow Nanospheres with Highly Enhanced Sensing Performances for Styrene.

Styrene, a chronic toxic gas, is of great harm to human health. It is urgently required to develop a portable, efficient, and inexpensive method to detect this toxic gas. Chemiresistive gas sensor based on semiconductor metal-oxides is considered as one of the best candidate suited to above features, while its sensitivity and selectivity are not enough high for the applications.

Facile Synthesis of Polyaniline Nanotubes Using Self-Assembly Method Based on the Hydrogen Bonding: Mechanism and Application in Gas Sensing.

Based on hydrogen bonding, the highly uniform polyaniline (PANI) nanotubes were synthesized by self-assembly method using citric acid (CA) as the dopant and the structure-directing agent by optimizing the molar ratio of CA to aniline monomer (Ani). Synthesis conditions like reaction temperature and mechanical stirring were considered to explore the effects of hydrogen bonding on the morphologies. The effects of CA on the final morphology of the products were also investigated.

Structure and thickness-dependent gas sensing responses to NO under UV irradiation for the multilayered ZnO micro/nanostructured porous thin films.

The structure and thickness of the chemiresistive thin films can significantly affect their gas sensing performances for the heating-typed sensors. Under light irradiation, however, their influences are still to be addressed. In present paper, the multilayered ZnO porous thin films with different (three types) micro/nanostructures and controllable thickness are fabricated via layer by layer construction of the self-assembled colloidal-layers.

Detection of dimethyl methylphosphonate by thin water film confined surface-enhanced Raman scattering method.

It is important and necessary to effectively detect the chemical warfare agents, such as highly toxic never agent sarin. However, based on the surface-enhanced Raman scattering (SERS) effect, detection of nerve agent simulant dimethyl methylphosphonate (DMMP) which is weakly interacted with SERS-active substrate has been the most challenge for the routine SERS detection method. To overcome this challenge, we put forward a thin water film confined SERS strategy.

In situ synthesis of porous array films on a filament induced micro-gap electrode pair and their use as resistance-type gas sensors with enhanced performances.

Resistance-type metal-oxide semiconductor gas sensors with high sensitivity and low detection limit have been explored for practical applications. They require both sensing films with high sensitivity to target gases and an appropriate structure of the electrode-equipped substrate to support the sensing films, which is still challenging. In this paper, a new gas sensor of metal-oxide porous array films on a micro-gap electrode pair is designed and implemented by taking ZnO as a model material.

Micro/Nano gas sensors: a new strategy towards in-situ wafer-level fabrication of high-performance gas sensing chips.

Nano-structured gas sensing materials, in particular nanoparticles, nanotubes, and nanowires, enable high sensitivity at a ppb level for gas sensors. For practical applications, it is highly desirable to be able to manufacture such gas sensors in batch and at low cost. We present here a strategy of in-situ wafer-level fabrication of the high-performance micro/nano gas sensing chips by naturally integrating microhotplatform (MHP) with nanopore array (NPA).

Janus gas: reversible redox transition of Sarin enables its selective detection by an ethanol modified nanoporous SnO₂ chemiresistor.

A reversible janus gas redox transition was discovered in the trace Sarin sensing process using an ethanol-aged nanoporous SnO2 micro-chemiresistor, which was reliable to realize the identification of Sarin from other gases and even its simulant. This sensor also endows a rather low detection threshold of 6 ppb to Sarin.

Fabrication of silver nanoplate hierarchical turreted ordered array and its application in trace analyses.

Silver nanoplate hierarchical turreted ordered arrays were fabricated through an electro-deposition method on ordered acuate silicon nanocone templates. Such arrays can be used as SERS substrates for trace analyses of streptomycin sulphate, and exhibit high activity and stability. This work is of importance in practical applications based on the SERS effect of noble metal micro/nano-structured arrays.

Rapid synthesis of monodisperse Au nanospheres through a laser irradiation-induced shape conversion, self-assembly and their electromagnetic coupling SERS enhancement.

We develop a facile and effective strategy to prepare monodispersed Au spherical nanoparticles by two steps. Large-scale monocrystalline Au nanooctahedra with uniform size were synthesized by a polyol-route and subsequently Au nanoparticles were transformed from octahedron to spherical shape in a liquid under ambient atmosphere by non-focused laser irradiation in very short time. High monodispersed, ultra-smooth gold nanospheres can be obtained by simply optimizing the laser fluence and irradiation time.

Physical deposition improved SERS stability of morphology controlled periodic micro/nanostructured arrays based on colloidal templates.

An effective and inexpensive method is developed to fabricate periodic arrays by sacrificial colloidal monolayer template route by chemical deposition and further physical deposition. By a colloidal template induced precursor solution dipping strategy, different periodic arrays of semi-hollow sphere array, inverse opal with monolayer pore arrays and hole arrays are obtained under different conditions. After magnetron sputtering deposition, their morphologies are changed to novel micro/nanostructured arrays of honeycomb-shaped arrays, hollow cavity arrays, and regular network arrays due to multiple direction deposition of sputtering deposition and shadow effect.

Wet etching-assisted colloidal lithography: a general strategy toward nanodisk and nanohole arrays on arbitrary substrates.

A simple and facile strategy is presented to fabricate the metal nanodisk and nanohole arrays based on a wet etching-assisted polystyrene colloidal lithography. Gold is chosen to demonstrate the validity of such a strategy. The hexagonally arranged Au nanodisk and nanohole arrays are thus fabricated with large area and good uniformity.

CuO-ZnO micro/nanoporous array-film-based chemosensors: new sensing properties to H2S.

CuO-ZnO micro/nanoporous array-films are synthesized by transferring a solution-dipped self-organized colloidal template onto a device substrate and sequent heat treatment. Their morphologies and structures are characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectrum analysis. Based on the sensing measurement, it is found that the CuO-ZnO films prepared with the composition of [Cu(2+)]/[Zn(2+)]=0.

Gold binary-structured arrays based on monolayer colloidal crystals and their optical properties.

A simple and flexible route is presented to fabricate a gold binary-structured ordered array by one step based on non-shadow deposition on a plasma etching-induced dualistic monolayer colloidal crystal. Such a Au binary-structure array is built of hexagonally arranged nanoshells and nanorings which stand between two adjacent nanoshells. Six gold nanorings surround each nanoshell.

Fabrication of gold nanoparticles by laser ablation in liquid and their application for simultaneous electrochemical detection of Cd2+, Pb2+, Cu2+, Hg2+.

In this paper, we demonstrated the fabrication of high active and high sensitive Au nanoparticles by laser ablation in liquid (LAL) method, and their application in electrochemical detection of heavy metal ions. First, LAL method are used to fabricate Au nanoparticles in water in a clean way. Second, the Au nanoparticles were assembled onto the surface of the glassy carbon (GC) electrode by an electrophoretic deposition method to form an AuNPs/GC electrode for electrochemical characterization and detection.