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Article
Publication date: 19 June 2017

Xuehai Guo, Guofeng Pan, Xin Ma, Xiangzhou Li, Ping He, Zhongqiu Hua and Haiqing Li

The purpose of this research is to synthesize Al2O3-ZnO thick films, study the effect of doping and optical excitation on their sensing properties and introduce an…

Abstract

Purpose

The purpose of this research is to synthesize Al2O3-ZnO thick films, study the effect of doping and optical excitation on their sensing properties and introduce an attractive candidate for acetone detection in practice.

Design/methodology/approach

ZnO nanoparticles doped with Al2O3 were prepared by sol-gel method and characterized via X-ray diffraction and field-emission scanning electron microscopy. The sensing properties to acetone were investigated with an irradiation of UV. The sensing mechanism was also discussed with UV-Vis spectroscopy.

Findings

The doping of Al2O3 promoted the sensing response and stability of ZnO nanoparticles. The optimum performance was obtained by 4.96 Wt.% Al2O3-ZnO. The response to acetone (1,000 ppm) was significantly increased to 241.81, even just at an operating temperature of 64°C. It was also demonstrated that optical excitation with UV irradiation greatly enhanced the sensing response and the sensitivity can reach up to 305.14.

Practical implications

The sensor fabricated from 4.96 Wt.% Al2O3-ZnO exhibited excellent acetone-sensing characteristics. It is promising to be applied in low power and miniature acetone gas sensors.

Originality/value

In the present research, the optimum performance was obtained by 4.96 Wt.% Al2O3-ZnO at a low operating temperature of 64°C. The sensing properties were enhanced significantly with optical excitation, and the sensing mechanism was discussed with UV-Vis spectroscopy which has been reported rarely before.

Details

Sensor Review, vol. 37 no. 3
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 22 May 2008

Alexander D. Klose and Andreas H. Hielscher

This paper sets out to give an overview about state‐of‐the‐art optical tomographic image reconstruction algorithms that are based on the equation of radiative transfer (ERT).

Abstract

Purpose

This paper sets out to give an overview about state‐of‐the‐art optical tomographic image reconstruction algorithms that are based on the equation of radiative transfer (ERT).

Design/methodology/approach

An objective function, which describes the discrepancy between measured and numerically predicted light intensity data on the tissue surface, is iteratively minimized to find the unknown spatial distribution of the optical parameters or sources. At each iteration step, the predicted partial current is calculated by a forward model for light propagation based on the ERT. The equation of radiative is solved with either finite difference or finite volume methods.

Findings

Tomographic reconstruction algorithms based on the ERT accurately recover the spatial distribution of optical tissue properties and light sources in biological tissue. These tissues either can have small geometries/large absorption coefficients, or can contain void‐like inclusions.

Originality/value

These image reconstruction methods can be employed in small animal imaging for monitoring blood oxygenation, in imaging of tumor growth, in molecular imaging of fluorescent and bioluminescent probes, in imaging of human finger joints for early diagnosis of rheumatoid arthritis, and in functional brain imaging.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 18 no. 3/4
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 18 September 2007

Wenjun Liu and Bozhi Yang

The goal of this review paper is to provide information on several commonly used thermography techniques in semiconductor and micro‐device industry and research today.

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Abstract

Purpose

The goal of this review paper is to provide information on several commonly used thermography techniques in semiconductor and micro‐device industry and research today.

Design/methodology/approach

The temperature imaging or mapping techniques include thin coating methods such as liquid crystal thermography and fluorescence microthermography, contact mechanical methods such as scanning thermal microscopy, and optical techniques such as infrared microscopy and thermoreflectance. Their principles, characteristics and applications are discussed.

Findings

Thermal issues play an important part in optimizing the performance and reliability of high‐frequency and high‐packing density electronic circuits. To improve the performance and reliability of microelectronic devices and also to validate thermal models, accurate knowledge of local temperatures and thermal properties is required.

Originality/value

The paper provides readers, especially technical engineers in industry, a general knowledge of several commonly used thermography techniques in the semiconductor and micro‐device industries.

Details

Sensor Review, vol. 27 no. 4
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 2 November 2017

Jiliang Mu, Zhang Qu, Zongmin Ma, Shaowen Zhang, Yunbo Shi, Jian Gao, Xiaoming Zhang, Huiliang Cao, li Qin, Jun Liu and Yanjun Li

This study aims to fabricate and manipulate ensemble spin of negative nitrogen-vacancy (NV) centres optimally for future solid atomic magnetometers/gyroscope. Parameters…

Abstract

Purpose

This study aims to fabricate and manipulate ensemble spin of negative nitrogen-vacancy (NV) centres optimally for future solid atomic magnetometers/gyroscope. Parameters for sample preparation most related to magnetometers/gyroscope are, in particular, the concentration and homogeneity of the NV centres, the parameters’ microwave antenna of resonance frequency and the strength of the microwave on NV centres. Besides, the abundance of other impurities such as neutral NV centres (NV0) and substitutional nitrogen in the lattice also plays a critical role in magnetic sensing.

Design/methodology/approach

The authors succeeded in fabricating the assembly of NV centres in diamond and they determined its concentration of (2-3) × 1016 cm−3 with irradiation followed by annealing under a high temperature condition. They explored a novel magnetic resonance approach to detect the weak magnetic fields that takes advantage of the solid-state electron ensemble spin of NV centres in diamond. In particular, the authors set up a magnetic sensor on the basis of the assembly of NV centres. They succeeded in fabricating the assembly of NV centres in diamond and determined its concentration. They also clarified the magnetic field intensity measured at different positions along the antenna with different lengths, and they found the optimal position where the signal of the magnetic field reaches the maximum.

Findings

The authors mainly reported preparation, initialization, manipulation and measurement of the ensemble spin of the NV centres in diamond using optical excitation and microwave radiation methods with variation of the external magnetic field. They determined the optimal parameters of irradiation and annealing to generate the ensemble NV centres, and a concentration of NV centres as high as 1016 cm−3 in diamond was obtained. In addition, they found that sensitivity of the magnetometer using this method can reach as low as 5.22 µT/Hz currently.

Practical implications

This research can shed light on the development of an atomic magnetometer and a gyroscope on the basis of the ensemble spin of NV centres in diamond.

Social implications

High concentration spin of NV in diamond is one of the advantages compared with that of the atomic vapor cells, because it can obtain a higher concentration. When increasing the spin concentration, the spin signal is easy to detect, and macro-atomic spin magnetometer become possible. This research is the first step for solid atomic magnetometers with high spin density and high sensitivity potentially with further optimization. It has a wide range of applications from fundamental physics tests, sensor applications and navigation to detection of NMR signals.

Originality/value

As has been pointed out, in this research, the authors mainly worked on fabricating NV centres with high concentration (1015-1016 cm−3) in diamond by using optimal irradiation and annealing processes, and they quantitatively defined the NV concentration, which is important for the design of higher concentration processes in the magnetometer and gyroscope. Until now, few groups can directly define the NV concentration. Besides, the authors optimized the microwave antenna parameters experimentally and explored the dependence between the splitting of the magnetic resonance and the magnetic fields, which dictated the minimum detectable magnetic field.

Details

Sensor Review, vol. 37 no. 4
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 26 June 2019

Raj K. Vinnakota and Dentcho A. Genov

Selective laser melting (SLM) is an advanced rapid prototyping or additive manufacturing technology that uses high power density laser to fabricate metal/alloy components…

Abstract

Purpose

Selective laser melting (SLM) is an advanced rapid prototyping or additive manufacturing technology that uses high power density laser to fabricate metal/alloy components with minimal geometric constraints. The SLM process is multi-physics in nature and its study requires development of complex simulation tools. The purpose of this paper is to study – for the first time, to the best of the authors’ knowledge – the electromagnetic wave interactions and thermal processes in SLM based dense powder beds under the full-wave formalism and identify prospective metal powder bed particle distributions that can substantially improve the absorption rate, SLM volumetric deposition rate and thereby the overall build time.

Design/methodology/approach

We present a self-consistent thermo-optical model of the laser-matter interactions pertaining to SLM. The complex electromagnetic interactions and thermal effects in the dense metal powder beds are investigated by means of full-wave finite difference simulations. The model allows for accurate simulations of the excitation of gap, bulk and surface electromagnetic resonance modes, the energy transport across the particles, time dependent local permittivity variations under the incident laser intensity, and the thermal effects (joule heating) due to electromagnetic energy dissipation.

Findings

Localized gap and surface plasmon polariton resonance effects are identified as possible mechanisms toward improved absorption in small and medium size titanium powder beds. Furthermore, the observed near homogeneous temperature distributions across the metal powders indicates fast thermalization processes and allows for development of simple analytical models to describe the dynamics of the SLM process.

Originality/value

To the best of the authors’ knowledge, for the first time the electromagnetic interactions and thermal processes with dense powder beds pertaining to SLM processes are investigated under full-wave formalism. Explicit description is provided for important SLM process parameters such as critical laser power density, saturation temperature and time to melt. Specific guidelines are presented for improved energy efficiency and optimization of the SLM process deposition rates.

Article
Publication date: 1 February 1986

J.A. Neff

A major limitation to achieving significant speed increases in VLSI lies in the metallic interconnects. They are costly not only from the charge transport standpoint but…

Abstract

A major limitation to achieving significant speed increases in VLSI lies in the metallic interconnects. They are costly not only from the charge transport standpoint but also from capacitive loading effects. The Defense Advanced Research Projects Agency, in pursuit of fifth generation supercomputing, is investigating alternatives to the VLSI metallic interconnects, especially the use of optical techniques to transport the information between chips or between boards. As the on‐chip performance of VLSI continues to improve via the scale‐down of the logic elements, the problems associated with transferring data off and onto the chip become more severe. The use of optical carriers to transfer the information within the computer is very appealing from several viewpoints. Besides the potential for gigabit propagation rates, the conversion from electronics to optics conveniently provides a decoupling of the various circuits from one another. Significant gains will also be realised in reducing cross‐talk between the metallic routings, and the interconnects need no longer be constrained to the plane of the VLSI chip. In addition, optics can offer an increased programming flexibility for restructuring the interconnect network.

Details

Microelectronics International, vol. 3 no. 2
Type: Research Article
ISSN: 1356-5362

Article
Publication date: 11 July 2019

Yaser Javed, Mohtashim Mansoor and Irtiza Ali Shah

Pressure, being one of the key variables investigated in scientific and engineering research, requires critical and accurate measurement techniques. With the advancements…

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Abstract

Purpose

Pressure, being one of the key variables investigated in scientific and engineering research, requires critical and accurate measurement techniques. With the advancements in materials and machining technologies, there is a large leap in the measurement techniques including the development of micro electromechanical systems (MEMS) sensors. These sensors are one to two orders smaller in magnitude than traditional sensors and combine electrical and mechanical components that are fabricated using integrated circuit batch-processing technologies. MEMS are finding enormous applications in many industrial fields ranging from medical to automotive, communication to electronics, chemical to aviation and many more with a potential market of billions of dollars. MEMS pressure sensors are now widely used devices owing to their intrinsic properties of small size, light weight, low cost, ease of batch fabrication and integration with an electronic circuit. This paper aims to identify and analyze the common pressure sensing techniques and discuss their uses and advantages. As per our understanding, usage of MEMS pressure sensors in the aerospace industry is quite limited due to cost constraints and indirect measurement approaches owing to the inability to locate sensors in harsh environments. The purpose of this study is to summarize the published literature for application of MEMS pressure sensors in the said field. Five broad application areas have been investigated including: propulsion/turbomachinery applications, turbulent flow diagnosis, experimentalaerodynamics, micro-flow control and unmanned aerial vehicle (UAV)/micro aerial vehicle (MAV) applications.

Design/methodology/approach

The first part of the paper deals with an introduction to MEMS pressure sensors and mathematical relations for its fabrication. The second part covers pressure sensing principles followed by the application of MEMS pressure sensors in five major fields of aerospace industry.

Findings

In this paper, various pressure sensing principles in MEMS and applications of MEMS technology in the aerospace industry have been reviewed. Five application fields have been investigated including: Propulsion/Turbomachinery applications, turbulent flow diagnosis, experimental aerodynamics, micro-flow control and UAV/MAV applications. Applications of MEMS sensors in the aerospace industry are quite limited due to requirements of very high accuracy, high reliability and harsh environment survivability. However, the potential for growth of this technology is foreseen due to inherent features of MEMS sensors’ being light weight, low cost, ease of batch fabrication and capability of integration with electric circuits. All these advantages are very relevant to the aerospace industry. This work is an endeavor to present a comprehensive review of such MEMS pressure sensors, which are used in the aerospace industry and have been reported in recent literature.

Originality/value

As per the author’s understanding, usage of MEMS pressure sensors in the aerospace industry is quite limited due to cost constraints and indirect measurement approaches owing to the inability to locate sensors in harsh environments. Present work is a prime effort in summarizing the published literature for application of MEMS pressure sensors in the said field. Five broad application areas have been investigated including: propulsion/turbomachinery applications, turbulent flow diagnosis, experimental aerodynamics, micro-flow control and UAV/MAV applications.

Details

Sensor Review, vol. 39 no. 5
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 8 January 2018

Yuxin Miao, Guofeng Pan, Caixuan Sun, Ping He, Guanlong Cao, Chao Luo, Li Zhang and Hongliang Li

The purpose of this paper is to study the effect of doping, annealing temperature and visible optical excitation on CuO-ZnO nanocomposites’ acetone sensing properties and…

Abstract

Purpose

The purpose of this paper is to study the effect of doping, annealing temperature and visible optical excitation on CuO-ZnO nanocomposites’ acetone sensing properties and introduce an attractive candidate for acetone detection at about room temperature.

Design/methodology/approach

ZnO nanoparticles doped with CuO were prepared by sol-gel method, and the structure and morphology were characterized via X-ray diffraction, scanning electron microscope, energy dispersive spectroscopy and Brunauer-Emmett-Teller. The photoelectric responses of CuO-ZnO nanocomposites to cetone under the irradiation of visible light were investigated at about 30°C. The photoelectric response mechanism was also discussed with the model of double Schottky.

Findings

The doping of CuO enhanced performance of ZnO nanoparticles in terms of the photoelectric responses and the gas response and selectivity to acetone of ZnO nanoparticles, in addition, decreasing the operating temperature to about 30ºC. The optimum performance was obtained by 4.17% CuO-ZnO nanocomposites. Even at the operating temperature, about 30ºC, the response to 1,000 ppm acetone was significantly increased to 579.24 under the visible light irradiation.

Practical implications

The sensor fabricated by 4.17% CuO-ZnO nanocomposites exhibited excellent acetone-sensing characteristics at about 30ºC. It is promising to be applied in low power and miniature acetone gas sensors.

Originality/value

In the present research, a new nanocomposite material of CuO-ZnO was prepared by Sol-gel method. The optimum gas sensing properties to acetone were obtained by 4.17% CuO-ZnO nanocomposites at about 30ºC operating temperature when it was irradiated by visible light with the wavelength more than 420 nm.

Details

Sensor Review, vol. 38 no. 3
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 25 January 2008

Vinod Kumar Khanna

This paper aims to discover the novelties in biosensor fabrication brought about by breakthroughs in nanomaterials and process techniques, the resulting enhancement in…

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Abstract

Purpose

This paper aims to discover the novelties in biosensor fabrication brought about by breakthroughs in nanomaterials and process techniques, the resulting enhancement in biosensor functionalities, new applications and future possibilities.

Design/methodology/approach

The impact of nanotechnology on biosensor advancement has been examined. Different directions of biosensor research in the nano era have been highlighted. These include the efforts made through nanotechnology to improve the performance parameters of the existing biosensors, and for implementation of innovative biosensor concepts.

Findings

Nanotechnology is a key technology in biosensor development. It has permeated into the biosensor field and brought in its wake far‐reaching changes.

Practical implications

Biosensor science and engineering are central to virtually all aspects of life including medical diagnostics, environmental monitoring and biotechnological process control. Therefore, the progress in biosensors brought about by nanotechnology influences one's everyday life.

Originality/value

The study helps in understanding the applications of nanotechnology in fabricating a new generation of biosensors with improved characteristics. It provides information of value to those involved in biosensor research.

Details

Sensor Review, vol. 28 no. 1
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 1 April 1988

Peter McGeehin of Compton Consultants explains the trends taking place.

Abstract

Peter McGeehin of Compton Consultants explains the trends taking place.

Details

Sensor Review, vol. 8 no. 4
Type: Research Article
ISSN: 0260-2288

1 – 10 of 659