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Li X.,CAS Shanghai State Key Laboratory of Transducer Technology | Lee D.-W.,Chonnam National University
Measurement Science and Technology | Year: 2012

This topical review is focused on microcantilever-based sensing and probing functions that are realized by integrating a mechanically compliant cantilever with self-sensing and self-actuating elements, specific sensing materials as well as functionalized nano-tips. Such integrated cantilever devices have shown great promise in ultra-sensitive applications such as on-the-spot portable bio/chemical detection and in situ micro/nanoscale surface analysis and manipulation. The technical details of this review will be given in a sequence of cantilever sensors and, then, cantilever-tip probes. For the integrated cantilever sensors, the frequency-output style dynamic cantilevers are described first, with the contents including optimized resonance modes, sensing-group-modified nanostructures for specific bio/chemical mass adsorption and nanoscale sensing effects, etc. Thereafter, the static cantilever sensors for surface-stress detection are described in the sequence of the sensing mechanism, surface modification of the sensitive molecule layer and the model of specific reaction-induced surface-energy variation. After technical description of the cantilever sensors, the emphasis of the review moves to functionalized nano-tip equipped cantilever-tip probing devices. The probing functions are not only integrated on the cantilever but also integrated at the sharp apex of the tip. After description of single integrated cantilever probes and their applications in surface scanning and imaging, arrayed cantilever-tip devices and their simultaneous parallel operation for high throughput imaging and nanomechanical data storage are also addressed. With cantilever-tip probes as key elements, micro-analysis instruments are introduced that can be widely used for macro/nanoscale characterizations. © 2012 IOP Publishing Ltd.

Tao B.,CAS Shanghai State Key Laboratory of Transducer Technology | Tao B.,Qiqihar University | Zhang J.,CAS Shanghai State Key Laboratory of Transducer Technology | Hui S.,CAS Shanghai State Key Laboratory of Transducer Technology | And 2 more authors.
Electrochimica Acta | Year: 2010

A novel electrochemical methanol sensor based on a catalytic electrode of palladium-nickel/silicon nanowires (Pd-Ni/SiNWs) is presented in this paper. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and electrochemical methods are employed to investigate the Pd-Ni/SiNWs electrode materials. These nanocomposite materials exhibit a highly ordered, wire-like structure with a wire length of ∼50 μm and a wire diameter ranging from 100 to 300 nm. The substrate has good electrocatalytic activity towards the oxidation of methanol in alkaline solutions. The performances of the prototype sensor are characterized by cyclic voltammetry and fixed potential amperometry techniques. In a 1 mol L-1 KOH solution containing different methanol concentrations, the sensor exhibits a good sensitivity of 1.96 mA mmol-1 L cm-2 with R2 = 0.99 and the corresponding detection limit of 18 μmol L-1 (signal-to-noise ratio = 3, S/N = 3) for cyclic voltammetry. Meanwhile, the electrode also displays a sensitivity of 0.48 mA mmol-1 L cm-2 with R2 = 0.98 and the corresponding detection limit of 25 μmol L-1 (S/N = 3) for a fixed potential amperometry at -0.3 V versus an Ag/AgCl reference electrode. The results demonstrate that the Pd-Ni/SiNWs catalytic electrode has potential as an efficient and integrated sensor for methanol detection. © 2010 Elsevier Ltd. All rights reserved.

Ren N.,Jiangsu University | Liu Z.,Jiangsu University | Wang Q.,Jiangsu University | Wang Q.,CAS Shanghai State Key Laboratory of Transducer Technology
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2015

Flat, B-doped, low-stress and non-stress polysilicon (poly-Si) thin films were deposited by low pressure chemical vapor deposition (LPCVD). X-ray diffraction (XRD), combined with atomic force microscopy (AFM) and Raman system, UV-Raman measurements and spectroscopic ellipsometry, was used to study the microstructure, the morphology and optical properties of the films. The results indicate that the surface roughness is related to the grain size and the change in the microstructure. The B-doped poly-Si shows a tensile stress, while the flat poly-Si shows a high compressive stress. The bandgap of the B-doped poly-Si is the narrowest because of its most disordered microstructure. © 2015 Elsevier B.V.

Liu Q.,Zhejiang University | Liu Q.,CAS Shanghai State Key Laboratory of Transducer Technology | Wu C.,Zhejiang University | Cai H.,Zhejiang University | And 4 more authors.
Chemical Reviews | Year: 2014

A biosensor is an analytical device that can be used for detecting analytes and combines a biological component with a physicochemical detecting transducer. In recent years, biosensors have rapidly expanded and evolved in many new fields such as molecularly sensitive receptors, biomimetic sensors, and nanotechnologies. In contrast to molecule-based approaches, cell-based biosensors have a broad spectrum of detection capabilities. Moreover, in addition to analyte sensing and detecting, cell-based biosensors can provide the advantages of rapid and sensitive analysis for in situ monitoring with cells. Cells naturally encapsulate molecular sensor arrays. Enzymes, receptors, and ion channels, all with a stable status, could respond to their corresponding analytes via a native cellular mechanism.

Tang J.,CAS Shanghai State Key Laboratory of Transducer Technology | Tang J.,University of Chinese Academy of Sciences | Sun X.,CAS Shanghai State Key Laboratory of Transducer Technology | Luo L.,CAS Shanghai State Key Laboratory of Transducer Technology
Journal of Micromechanics and Microengineering | Year: 2011

A wafer-level microwave multi-chip module (MMCM) packaging process is presented. Thick photosensitive-benzocyclobutene (photo-BCB) polymer (about 25 νm/layer) is used as the dielectric for its simplified process and the capability of obtaining desirable electrical, chemical and mechanical properties at high frequencies. The MMCM packaging structure contains a monolithic microwave integrated circuit (MMIC) chip embedded in a lossy-silicon wafer, a microwave band-pass filter (BPF) and two layers of BCB/Au interconnection. Key processes of fabrication are described in detail. The non-uniformity of BCB film and the sidewall angle of the via-holes for inter-layer connection are tested. Via-chains prepared by metal/BCB multilayer structures are tested through the Kelvin test structure to investigate the resistances of inter-layer connection. The average value is measured to be 73.5 mΩ. The electrical characteristic of this structure is obtained by a microwave transmission performance test from 15 to 30 GHz. The measurement results show good consistency between the bare MMIC die and the packaged die in the test frequency band. The gain of the MMIC chip after packaging is better than 18 dB within the designed operating frequency range (from 23 to 25 GHz). When the packaged MMIC chip is connected to a BPF, the maximum gain is still measured to reach 11.95 dB at 23.8 GHz. © 2011 IOP Publishing Ltd.

Yang Y.,CAS Shanghai State Key Laboratory of Transducer Technology | Li X.,CAS Shanghai State Key Laboratory of Transducer Technology
IEEE Electron Device Letters | Year: 2011

A giant piezoresistive coefficient is, for the first time, experimentally measured for n-type nanothick silicon. Compared to n-type bulk silicon, the nanothick silicon resistors exhibit at least one order of magnitude higher piezoresistive coefficient. Based on 2-D quantum confinement effect, our theoretic calculation indicates that the piezoresistive sensitivity will decrease and approach to zero, along with continually thinning the n-type silicon resistor. Thus, quantum effect is not responsible for the giant piezoresistance of the n-type nanothick silicon. By phenomenon analysis and qualitative modeling, we attribute the obtained giant piezoresistance to stress-enhanced Si/SiO2 interfacial electron-trapping effect. Hence, the giant piezoresistance in n-type nanothick silicon is dominantly originated from electron concentration change, instead of equivalent mobility change in conventional piezoresistance of bulk silicon. © 2006 IEEE.

Yao W.,CAS Shanghai State Key Laboratory of Transducer Technology | Chen X.,CAS Shanghai State Key Laboratory of Transducer Technology | Zhang J.,CAS Shanghai State Key Laboratory of Transducer Technology
Sensors and Actuators, B: Chemical | Year: 2010

This paper describes an application of polymer encapsulated gold nanoparticles used as relative humidity (RH) sensors. The gold nanoparticles are prepared by a most popular method, and the polymer, polyvinyl alcohol (PVA), is used to encapsulate Au for getting core-shell hybrid structures. Scanning electron microscopy (SEM) and atom force microscopy (AFM) were used to observe the structural and morphological properties of the polymer encapsulated gold nanoparticles. X-ray diffraction (XRD) was used to estimate the crystallite size of gold nanoparticles. And then gold (Au) and gold-polyvinyl alcohol (Au-PVA) nanoparticles were applied to construct Au sensors and Au-PVA sensors, respectively. Sensing experiments were examined by measuring the capacitance shift of Au and Au-PVA sensors which have been put into different relative humidity environments. The results showed that the Au-PVA sensors had higher humidity sensitivity, better stability, faster humidity response and better reproducibility than the Au sensors. Therefore, a capacitive humidity sensor based on Au-PVA core-shell nanocomposites is potentially developed. © 2009 Elsevier B.V. All rights reserved.

Zhou D.,CAS National Center for Nanoscience and Technology | Zhou D.,CAS Shanghai State Key Laboratory of Transducer Technology | Zhang T.-L.,CAS National Center for Nanoscience and Technology | Han B.-H.,CAS National Center for Nanoscience and Technology | Han B.-H.,CAS Shanghai State Key Laboratory of Transducer Technology
Microporous and Mesoporous Materials | Year: 2013

A graphene-based magnetic hybrid porous material was fabricated through a one-step solvothermal approach using graphene oxide and iron precursors, in which the reduction of the graphene oxide and the formation of the magnetic iron oxide nanoparticles proceeded simultaneously. Owing to the driving force of the chemisorption interaction, the graphene sheets and magnetic nanoparticles assembled into three-dimensional structures. The materials exhibit superparamagnetism (saturation magnetization: 0.1-20.3 emu g -1), and were characterized by X-ray diffraction, thermal gravimetric analysis, transmission electron microscopy, infrared spectra and Raman spectroscopy. Gas sorption analysis shows the as-prepared hybrid material has high porosity (BET specific surface area: 418-901 m 2 g -1), and the hydrogen uptake value ranges from 0.88 to 1.44 wt.%. © 2012 Elsevier Inc. All rights reserved.

Wang Q.,Jiangsu University | Zhang J.,Jiangsu University | Yuan S.,Jiangsu University | Li X.,CAS Shanghai State Key Laboratory of Transducer Technology
Applied Physics Letters | Year: 2012

Graphene has many unique properties that make it an ideal material for fundamental studies as well as for potential applications. This paper mainly focuses on the electrical properties of a few layers of graphene (FLG). The I-V curves of the FLG devices pass though the origin, but the relationship between the voltage and current is nonlinear. This phenomenon may be due to tunneling current when voltage is applied to the FLG. Also, charged impurities on the sample cause shifts in the maximum resistance point in FLG R-V curves, with fewer graphene layers corresponding to larger changes in resistance. © 2012 American Institute of Physics.

Zhou D.,CAS National Center for Nanoscience and Technology | Zhou D.,CAS Shanghai State Key Laboratory of Transducer Technology | Cheng Q.-Y.,CAS National Center for Nanoscience and Technology | Cheng Q.-Y.,CAS Shanghai State Key Laboratory of Transducer Technology | And 2 more authors.
Carbon | Year: 2011

We developed a simple surfactant-free approach to graphene dispersion through a solvothermal reduction of graphene oxides in N,N-dimethylformamide, and the concentration of the as-prepared graphene dispersion can reach up to 0.3 mg mL-1. The as-prepared graphene could be re-dispersed well in more than six kinds of solvents, such as N-methylpyrrolidone, N,N-dimethylacetamide, and acetonitrile. In the solvothermal reduction process, no extra reducing agent and/or stabilizer is needed, and the deoxygenation is promoted by the relatively high temperature and autogenous pressure in the autoclave. Atomic force microscopy analysis shows most of the graphene sheets in the as-prepared dispersion are single-layered. X-ray photoelectron spectroscopy, thermal gravimetric analysis, and infrared spectroscopy confirm the efficient removal of the oxygen-containing groups. © 2011 Elsevier Ltd. All rights reserved.

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