Sensor Review

Robert Bogue

2012 Sensor Review

doi: 10.1108/02602281211209374

Purpose – The purpose of this paper is to review the technology and applications of solar‐powered sensors. Design/methodology/approach – Following a short introduction, this paper first considers photovoltaic technology and then describes a selection of solar‐powered sensors and their applications. Findings – It is shown that solar‐powered sensors may be used as nodes in wireless sensor networks and also as stand‐alone devices. They offer a number of key operational and economic benefits and find applications in such diverse fields as structural and environmental monitoring, traffic management, weather forecasting, agriculture, process control, gas detection, satellite remote sensing and healthcare. Originality/value – The paper illustrates the important role that solar‐powered sensors and systems play in a wide range of applications and industries.

Richard Bloss

2012 Sensor Review

doi: 10.1108/02602281211209383

Purpose – The purpose of this paper is to review the Automate Show (vision and robotics), The Promat Show (material handling) that run jointly in Chicago, plus the Sensor Expo, with emphasis on the new sensor innovations and applications on display. Design/methodology/approach – The paper draws on in‐depth interviews with exhibitors of sensors of all types at these recent shows. Findings – Sensor suppliers have been busy applying wireless and energy harvesting technology to their devices. Vision suppliers continue to expand the capabilities of the video eye with 3D and other innovations. Practical implications – System integrators and users have an ever‐growing array of new sensor technologies to answer previously tough application needs. Wireless sensors and innovative vision systems, including 3‐D, offer new answers to material handling and other applications. MEMS commercialization development continues to drive ahead. Originality/value – Users and system integrators have an ever‐increasing range of innovative sensor solutions to help solve those previously difficult application requirements. For example, adding smart vision to logistic applications makes them faster, more accurate and more autonomous.

Gary Hunter; Randy Vander Wal; Laura Evans; Jennifer Xu; Gordon Berger; Michael Kullis; Azlin Biaggi‐Labiosa

2012 Sensor Review

doi: 10.1108/02602281211209392

Purpose – The development of chemical sensors based on nanostructures, such as nanotubes or nanowires, depends on the capability to reproducibly control the processing of the sensor. Alignment and consistent electrical contact of nanostructures on a microsensor platform is challenging. This can be accomplished using labor‐intensive approaches, specialized processing technology, or growth of nanostructures in situ. However, the use of standard microfabrication techniques for fabricating nanostructured microsensors is problematic. The purpose of this paper is to address this challenge using standard photoresist processing combined with dielectrophoresis. Design/methodology/approach – Nanostructures are suspended in photoresist and aligned between opposing sawtooth electrode patterns using an alternating current (AC) electric field (dielectrophoresis). The use of photoresist processing techniques allow the burying of the nanostructures between layers of metal, thus improving the electrical contact of the nanostructures to the microsensor platform. Findings – This approach is demonstrated for both multi‐walled carbon nanotubes and tin oxide nanowires. Preliminary data show the electrical continuity of the sensor structure as well as the response to various gases. Research limitations/implications – It is concluded that this approach demonstrates a foundation for a new tool for the fabrication of microsensors using nanostructures, and can be expanded towards enabling the combination of common microfabrication techniques with nanostructured sensor development. Originality/value – This approach is intended to address the significant barriers of deposition control, contact robustness, and simplified processing to realizing the potential of nanotechnology as applied to sensors.

Guofu Qiao; Huigang Xiao; Yi Hong; Yuelan Qiu

2012 Sensor Review

doi: 10.1108/02602281211209400

Purpose – Corrosion sensors and networks are the most effective techniques to obtain the corrosion information and recognize the corrosion status of reinforced concrete structures. However, reference electrode is the key element to provide the baseline for potential control of the corrosion monitoring sensors during corrosion measurement process. Therefore, the purpose of this paper is to provide the novel solid‐state reference electrode for the corrosion sensors. Design/methodology/approach – A solid‐state Ag/AgCl reference electrode has been prepared. Furthermore, the performance of the reference electrode, such as stability, temperature response, anti‐polarization and influence of the concrete admixture, has been investigated. Findings – The results indicate that the balance potential and the temperature coefficient of the reference electrode are 3.64±1mv (vs. SCE) at 25°C and −0.51 mv/°C±0.03 mv/°C, respectively. Furthermore, the polarization curve exhibits characteristics of three stages as the polarization current is in (−10μA/cm2,+10μA/cm2). Additionally, the reference electrode is insensitive to the concrete admixtures which include Na2SO4, NaCl, NaNO3 and NaNO2. Originality/value – The research provides the key element for the corrosion monitoring sensors to integrate structural health monitoring system in future.

M.F. Rahmat; N.S. Kamaruddin

2012 Sensor Review

doi: 10.1108/02602281211209419

Purpose – The use of pneumatic conveying of solid bulk over long distance has become a popular technique due to low operational cost, low maintenance requirement, layout flexibility and ease of automation. The purpose of this paper is to identifity the flow regime in a pneumatic conveyor system by electrodynamic sensor placed around the pipe using fuzzy logic tools. Design/methodology/approach – Electrical charge tomography is used to detect the existence of inherent charge on the moving particles through the pipe. Linear back projection algorithm and filtered back projection algorithm are employed to produce tomography image. Baffles of different shapes are inserted to create various flow regimes, such as full flow, three quarter flow, half flow and quarter flow. Fuzzy logic tools are used to identify different flow regimes and produce filtered back concentration profiles for each flow regime. Findings – The results show significant improvement in the pipe flow image resolution and measurement. Originality/value – This paper presents a flow identifier method using electrical charge tomography and fuzzy logic to monitor solid particles flow in pipeline.

Ahmad Fairuz Omar; Mohd Zubir MatJafri

2012 Sensor Review

doi: 10.1108/02602281211209428

Purpose – The purpose of this paper is to present a comparative study between two low‐cost turbidimeter designs using a multi purpose Optical Fiber NIR System (OF‐NIRS), Optical Fiber NIR System‐Modified (OF‐NIRS‐M) and High Sensitivity NIR System (HS‐NIRS) conducted in the development of a turbidimeter by closely replicating the existing standard design guideline. Optical method is a typical measuring technique that has been applied intensively for the measurement of water turbidity. Design/methodology/approach – Comprehensive guidelines for the development of turbidimeter have been stated by the United States Environmental Protection Agency (EPA Method 180.1) and the International Organization for Standardization (ISO 7027) and have been used as standards by instrument's manufacturers world wide, including the designs presented in this work. The development commonly does not only establish through physical instrumentation aspects, but also emphasizes on the physics of light‐matter interaction such as scattering and absorption that is embedded within the science of turbidity. The individual system design is the assembly of light emitting diode (LED) and photo detector with near infrared (NIR) band, amplifier, 12‐bit analogue to digital converter (ADC) and Basic Stamp 2pe microcontroller. Findings – The measurement by OF‐NIRS produces coefficient of determination, R2=0.8881 with standard error of 20.33 NTU while HS‐NIRS produces higher precision result with R2=0.995 with standard error of 1.809 NTU. A modified version of OF‐NIRS (OF‐NIRS‐M) has been introduced and consists of direct emission of NIR radiation to the sample. OF‐NIRS‐M produces R2=0.9921 with standard error of 2.37 NTU, a high linearity result, comparable to HS‐NIRS. Originality/value – This research introduced a fundamental design of a turbidimeter by following closely to the existing standards at much lower cost. This work presents a comparative study between two main designs that utilize different types of photo detector and amplification circuitry and enables related industry to develop their own in‐house turbidity monitoring system with flexible sensitivity.

Alfin Leo; Gino Rinaldi; Ion Stiharu; Rama Bhat

2012 Sensor Review

doi: 10.1108/02602281211209437

Purpose – It is currently difficult to measure temperature and pressure in harsh environments. Such measurements are limited by either the ability of the sensing element or the associated electrical wiring to withstand the operating environment. This is unfortunate as temperature and pressure are important measurands in various engineering structures as they provide critical information on the operating condition of the structure. Hence, there is a need to address this shortcoming. Such a sensor in place would enhance the operating efficiency thereby reducing the pollution burden and its impact on the environment. The purpose of this paper is to present theoretical and preliminary experimental results for a co‐integrated pressure and temperature sensor for harsh environments. Design/methodology/approach – This work describes a co‐integrated pressure‐temperature wireless sensing scheme. The approach presented herein provides the possibility of measuring dynamic pressure and temperature within an enclosed volume using acoustic signals. Resonance tube physics is exploited for the temperature sensing. A microphone is used to obtain the acoustic signal whose frequency is a function of the temperature and the tube geometry. Findings – The dynamic pressure is measured from the calibrated amplitude of the pressure wave signal measured by the microphone. The temperature can be measured through the shift of the standing wave frequency with a resolution of <1°C. The resonance tube can be fabricated using any material that resists harsh environments. The geometry of the tube can be tailored for any specific frequency range, as the application warrants. Also, this provides a means for accurate temperature compensation of pressure sensor data from high temperature environments. A Matlab/Simulink model is developed and presented for the acquisition of acoustic signals through the wall of an enclosed volume. For these applications the standing wave signal transmitted through the enclosure wall becomes a function of the wall material and wall thickness. Preliminary experimental results are presented in which a DC fan is used for generating the dynamic pressure in a varying temperature environment. Research limitations/implications – The major issue is the separation of the noise from the signal. As various applications yield specific signal noise, the problem needs detailed data to be addressed. Practical implications – Temperature and dynamic pressure could be recorded/monitored in very harsh environment conditions such as chemical reactors. Originality/value – This work demonstrates the possibility of employing a co‐integrated acoustic sensing scheme in which both pressure and temperature are measured simultaneously with a sole sensor. The major advantage with acoustic sensing is the wireless transmission of data. This allows for non‐invasive measurement from within enclosed systems. Direct real‐time temperature compensation is possible that does not require any compensation circuitry. Hence, pressure and temperature data may be obtained from caustic operating environments whose access is otherwise not feasible.

Ovidiu Ghita; Dana Ilea; Antonio Fernandez; Paul Whelan

2012 Sensor Review

doi: 10.1108/02602281211209446

Purpose – The purpose of this paper is to review and provide a detailed performance evaluation of a number of texture descriptors that analyse texture at micro‐level such as local binary patterns (LBP) and a number of standard filtering techniques that sample the texture information using either a bank of isotropic filters or Gabor filters. Design/methodology/approach – The experimental tests were conducted on standard databases where the classification results are obtained for single and multiple texture orientations. The authors also analysed the performance of standard filtering texture analysis techniques (such as those based of LM and MR8 filter banks) when applied to the classification of texture images contained in standard Outex and Brodatz databases. Findings – The most important finding resulting from this study is that although the LBP/C and the multi‐channel Gabor filtering techniques approach texture analysis from a different theoretical perspective, in this paper the authors have experimentally demonstrated that they share some common properties in regard to the way they sample the macro and micro properties of the texture. Practical implications – Texture is a fundamental property of digital images and the development of robust image descriptors plays a crucial role in the process of image segmentation and scene understanding. Originality/value – This paper contrast, from a practical and theoretical standpoint, the LBP and representative multi‐channel texture analysis approaches and a substantial number of experimental results were provided to evaluate their performance when applied to standard texture databases.

Aashis S. Roy; Ameena Parveen; Ambika Prasad; Koppalkar R. Anilkumar

2012 Sensor Review

doi: 10.1108/02602281211209455

Purpose – The purpose of this paper is to study the sensitivity and selectivity properties of polyaniline/tantalum pentoxide (PANI/Ta 2 O 5 ) composite to liquid petroleum gas (LPG). Design/methodology/approach – Polyaniline/tantalum pentaoxide (PANI/Ta 2 O 5 ) composites were synthesized by in situ chemical polymerization method using ammonium persulphate as an oxidizing agent. This is the novel polymerization process for the direct synthesis of emeraldine salt phase of the polymer. The composites were characterized by FTIR, XRD and SEM. Temperature dependence conductivity of the composites shows thermally activated behaviour. Sensitivity and selectivity of the composites are studied. Findings – The PANI/ Ta 2 O 5 composites of 20 wt% and 30 wt% are showing maximum change in resistance against time when compared to pure PANI and other polyaniline composites when exposed to LPG. The 20 wt % composites show maximum sensitivity of 83% to LPG. The selectivity studies reveals that LPG could be sensed better when compared to oxyacetylene and other test gases. Practical implications – Selectivity studies have been carried out and the sensor proved to be better than metal oxides sensors. Social implications – The sensing material is of low cost. Originality/value – To the best of the authors' knowledge, studies on Ta 2 O 5 ‐based gas sensor have not been reported previously.