A new issue of this journal has just been published. To see abstracts of the papers it contains (with links through to the full papers) click here:
Selected papers from the latest issue:
Gradient heat flux sensors for high temperature environments
12 March 2012, 09:24:04
Publication year: 2012
Source:Sensors and Actuators A: Physical, Volume 176
Andrey V. Mityakov, Sergey Z. Sapozhnikov, Vladimir Y. Mityakov, Andrei A. Snarskii, Maxim I. Zhenirovsky, Juha J. Pyrhönen
The paper studies gradient heat flux sensors (GHFS) based on artificial anisotropic thermoelements. Fundamentals, manufacturing technique and examples of applications in thermal measurement experiments are presented. Comparison of different types of sensors is provided.
Source:Sensors and Actuators A: Physical, Volume 176
Andrey V. Mityakov, Sergey Z. Sapozhnikov, Vladimir Y. Mityakov, Andrei A. Snarskii, Maxim I. Zhenirovsky, Juha J. Pyrhönen
The paper studies gradient heat flux sensors (GHFS) based on artificial anisotropic thermoelements. Fundamentals, manufacturing technique and examples of applications in thermal measurement experiments are presented. Comparison of different types of sensors is provided.
Design and characterization of MEMS micromotor supported on low friction liquid bearing
12 March 2012, 09:24:04
Publication year: 2012
Source:Sensors and Actuators A: Physical, Volume 177
Mei Lin Chan, Brian Yoxall, Hyunkyu Park, Zhaoyi Kang, Igor Izyumin, Jeffrey Chou, Mischa M. Megens, Ming C. Wu, Bernhard E. Boser, David A. Horsley
This paper examines the performance of rotating microdevices incorporating a liquid bearing to couple a rotating element to a fixed substrate. Liquid bearing technology promises to significantly improve the durability and lifetime of micromechanical motors. Here, the fluid is confined between the rotor and stator using surface patterning of a hydrophobic layer. Magnetic actuation of 10mm diameter silicon rotor is used to characterize the liquid bearing motor at rotation rates up to 1800rpm. Bearings with fluid thickness from 20 to 200μm are characterized. A minimum torque of 0.15μN-m is required to initiate rotation. At rotation rates above 720rpm, the rotor wobble is less than ±1mrad and the bearing exhibits viscous friction with a drag coefficient of 1.2×10−3 μN-m/rpm. The drag performance of the disk-type liquid bearing using H2O as the fluid is approximately 15 times lower than that demonstrated in a micro-ball bearing supported rotor.
Source:Sensors and Actuators A: Physical, Volume 177
Mei Lin Chan, Brian Yoxall, Hyunkyu Park, Zhaoyi Kang, Igor Izyumin, Jeffrey Chou, Mischa M. Megens, Ming C. Wu, Bernhard E. Boser, David A. Horsley
This paper examines the performance of rotating microdevices incorporating a liquid bearing to couple a rotating element to a fixed substrate. Liquid bearing technology promises to significantly improve the durability and lifetime of micromechanical motors. Here, the fluid is confined between the rotor and stator using surface patterning of a hydrophobic layer. Magnetic actuation of 10mm diameter silicon rotor is used to characterize the liquid bearing motor at rotation rates up to 1800rpm. Bearings with fluid thickness from 20 to 200μm are characterized. A minimum torque of 0.15μN-m is required to initiate rotation. At rotation rates above 720rpm, the rotor wobble is less than ±1mrad and the bearing exhibits viscous friction with a drag coefficient of 1.2×10−3 μN-m/rpm. The drag performance of the disk-type liquid bearing using H2O as the fluid is approximately 15 times lower than that demonstrated in a micro-ball bearing supported rotor.
An array of microliter-sized microbial fuel cells generating 100μW of power
12 March 2012, 09:24:04
Publication year: 2012
Source:Sensors and Actuators A: Physical, Volume 177
Seokheun Choi, Junseok Chae
We report an array of three microliter-sized microbial fuel cells (MFCs) connected in series. The three MFCs were integrated into a sandwich of two glass slides, incorporating two chambers of 50μL volumetric capacity that were separated by a cation exchange membrane (CEM). Each anolyte/catholyte chamber was defined by 500-μm thick PTEE (polytetrafluoroethylene) gaskets. The MFCs contained a Geobacter-enriched mixed bacterial culture and ferricyanide, which were independently driven into anolyte/catholyte chambers, respectively. The MFC array produced 100μW total power (33μW/cm2 or 667μW/cm3) and 1.8V output voltage, which are approximately 10 times and 4.5 times higher, respectively, than the maximum values of previously reported microliter-sized MFCs.
Source:Sensors and Actuators A: Physical, Volume 177
Seokheun Choi, Junseok Chae
We report an array of three microliter-sized microbial fuel cells (MFCs) connected in series. The three MFCs were integrated into a sandwich of two glass slides, incorporating two chambers of 50μL volumetric capacity that were separated by a cation exchange membrane (CEM). Each anolyte/catholyte chamber was defined by 500-μm thick PTEE (polytetrafluoroethylene) gaskets. The MFCs contained a Geobacter-enriched mixed bacterial culture and ferricyanide, which were independently driven into anolyte/catholyte chambers, respectively. The MFC array produced 100μW total power (33μW/cm2 or 667μW/cm3) and 1.8V output voltage, which are approximately 10 times and 4.5 times higher, respectively, than the maximum values of previously reported microliter-sized MFCs.
Piezoresistive CMOS sensor for out-of-plane normal stress
12 March 2012, 09:24:04
Publication year: 2012
Source:Sensors and Actuators A: Physical, Volume 176
Benjamin Lemke, Rajashree Baskaran, Oliver Paul
A piezoresistive sensor for measuring the temperature compensated sum (σ xx + σ yy )/2− βσ zz of the three mechanical normal stress components, where σ xx + σ yy , σ zz , and β denote the in-plane normal stress sum, the out-of-plane normal stress, and a numerical factor close to 1 is presented. The device is based on CMOS-compatible diffusions and exploits the piezoresistive effect acting on vertical current components. The sensor signal and resulting possibilities to extract mechanical stress components are analyzed. Experimental results illustrate the influence of design parameters and operating conditions on the sensor performance and are compared to a simple analytical sensor model. A second-order cross-sensitivity to in-plane shear stresses is discussed and determined experimentally. The temperature compensation is demonstrated by a force measurement with a deviation between the numerically expected and the experimentally extracted value smaller than 15% over the temperature range from 10°C to 60°C.
Source:Sensors and Actuators A: Physical, Volume 176
Benjamin Lemke, Rajashree Baskaran, Oliver Paul
A piezoresistive sensor for measuring the temperature compensated sum (σ xx + σ yy )/2− βσ zz of the three mechanical normal stress components, where σ xx + σ yy , σ zz , and β denote the in-plane normal stress sum, the out-of-plane normal stress, and a numerical factor close to 1 is presented. The device is based on CMOS-compatible diffusions and exploits the piezoresistive effect acting on vertical current components. The sensor signal and resulting possibilities to extract mechanical stress components are analyzed. Experimental results illustrate the influence of design parameters and operating conditions on the sensor performance and are compared to a simple analytical sensor model. A second-order cross-sensitivity to in-plane shear stresses is discussed and determined experimentally. The temperature compensation is demonstrated by a force measurement with a deviation between the numerically expected and the experimentally extracted value smaller than 15% over the temperature range from 10°C to 60°C.
Design of patterned leaf spring for sensor-probe with stable reflectivity and high sensitivity
12 March 2012, 09:24:04
Publication year: 2012
Source:Sensors and Actuators A: Physical, Volume 176
Yeon-Gwan Lee, Dae-Hyun Kim, Chun-Gon Kim
In sensors, integrated reflection mechanisms of the illuminating light to the reflection material on the proof mass require a strict single degree of motion because the accuracy almost entirely depends on the motion of the proof mass. Therefore, this paper describes the optimum design of a mass–spring structure that features high sensitivity and long linear elastic motion range of the leaf spring without rotation and lateral motion of the proof mass. Accordingly, finite element analyses were conducted to determine an optimal leaf spring pattern and to predict the probe performance. The optimum design of the leaf spring was determined by considering five criteria within the linear elastic region of the eight leaf spring models. Then, two types of leaf springs were manufactured, and the proposed mass–spring system integrated to the prototype was fabricated. The reliability of the FEA results and the performance of the fabricated mass–spring model were verified through the force–displacement curve test, the dynamic test, and the rotation test.
Source:Sensors and Actuators A: Physical, Volume 176
Yeon-Gwan Lee, Dae-Hyun Kim, Chun-Gon Kim
In sensors, integrated reflection mechanisms of the illuminating light to the reflection material on the proof mass require a strict single degree of motion because the accuracy almost entirely depends on the motion of the proof mass. Therefore, this paper describes the optimum design of a mass–spring structure that features high sensitivity and long linear elastic motion range of the leaf spring without rotation and lateral motion of the proof mass. Accordingly, finite element analyses were conducted to determine an optimal leaf spring pattern and to predict the probe performance. The optimum design of the leaf spring was determined by considering five criteria within the linear elastic region of the eight leaf spring models. Then, two types of leaf springs were manufactured, and the proposed mass–spring system integrated to the prototype was fabricated. The reliability of the FEA results and the performance of the fabricated mass–spring model were verified through the force–displacement curve test, the dynamic test, and the rotation test.
Microfabrication of compliant all-polymer MEMS thermal actuators
12 March 2012, 09:24:04
Publication year: 2012
Source:Sensors and Actuators A: Physical, Volume 177
Aaron P. Gerratt, Sarah Bergbreiter
This paper presents a fabrication process for compliant all-polymer MEMS actuators. This process allows high-aspect ratio conductive and non-conductive polymer features to be fabricated together in-plane. With this capability, robust all-polymer thermal actuators have demonstrated displacements as large at 100μm and forces as high as 55μN. The actuators are fabricated with elastomeric materials only, so they are very robust and can undergo large strains in both tension and bending and still operate once released.
Source:Sensors and Actuators A: Physical, Volume 177
Aaron P. Gerratt, Sarah Bergbreiter
This paper presents a fabrication process for compliant all-polymer MEMS actuators. This process allows high-aspect ratio conductive and non-conductive polymer features to be fabricated together in-plane. With this capability, robust all-polymer thermal actuators have demonstrated displacements as large at 100μm and forces as high as 55μN. The actuators are fabricated with elastomeric materials only, so they are very robust and can undergo large strains in both tension and bending and still operate once released.
Miniature conductive polymer actuators for high pressure generation in lab on chip systems
12 March 2012, 09:24:04
Publication year: 2012
Source:Sensors and Actuators A: Physical, Volume 177
M. Hiraoka, P. Fiorini, J. O’Callaghan, I. Yamashita, C. Van Hoof, M. Op de Beeck
We developed a miniaturized ‘syringe type’ pump (8mm diameter, 1mm thickness) which generates a flow rate of 2μL/min at a pressure of 3MPa. It consists of a stack of several conductive polymer (CP) layers intercalated with electrolyte layers. The stack is housed in a polycarbonate case specially conceived for integration in a lab-on-chip device. The dependence of strain on applied bias is investigated and the optimum working condition is determined. The actuator operates at a bias lower than 2V. A maximum strain of 13% is measured in the single CP layer when it expands against atmospheric pressure; this strain is reduced by only a factor of 3 when pressure increases up to 15MPa. The power efficiency of the actuator is also measured; it is in the range 10−3–10−4 and increases when pressure increases. Using a stacked actuator, consisting of 8 single actuators stacked on top of each other, a maximum strain of 5% is measured against atmospheric pressure.
Source:Sensors and Actuators A: Physical, Volume 177
M. Hiraoka, P. Fiorini, J. O’Callaghan, I. Yamashita, C. Van Hoof, M. Op de Beeck
We developed a miniaturized ‘syringe type’ pump (8mm diameter, 1mm thickness) which generates a flow rate of 2μL/min at a pressure of 3MPa. It consists of a stack of several conductive polymer (CP) layers intercalated with electrolyte layers. The stack is housed in a polycarbonate case specially conceived for integration in a lab-on-chip device. The dependence of strain on applied bias is investigated and the optimum working condition is determined. The actuator operates at a bias lower than 2V. A maximum strain of 13% is measured in the single CP layer when it expands against atmospheric pressure; this strain is reduced by only a factor of 3 when pressure increases up to 15MPa. The power efficiency of the actuator is also measured; it is in the range 10−3–10−4 and increases when pressure increases. Using a stacked actuator, consisting of 8 single actuators stacked on top of each other, a maximum strain of 5% is measured against atmospheric pressure.
Dynamic wood slice recognition using image blur information
12 March 2012, 09:24:04
Publication year: 2012
Source:Sensors and Actuators A: Physical, Volume 176
Chen Guang-Sheng, Zhao Peng
Image motion blur and defocus blur often occur when there is a relative motion between the imaging camera and the detected object. In this paper, we propose a robust wood slice recognition scheme using the low quality color wood slice images with the above-mentioned image blurs. First, a novel 2-D image measurement machine is devised, to obtain the object images sequentially by using a color camera. Second, the image-moment-based blur invariant features are calculated. Third, wood slice recognition is performed by using the computed Euclidean distance based on the moment invariants. We have experimentally proved that the effective use of image blur information improves the recognition accuracy of camera-captured wood slices. Moreover, the allowed maximum translation speed of the moving gallery is also discussed theoretically and experimentally. This scheme can identify the wood species by means of the slice recognition so as to judge the physical property and economic value of different wood species correctly.
Source:Sensors and Actuators A: Physical, Volume 176
Chen Guang-Sheng, Zhao Peng
Image motion blur and defocus blur often occur when there is a relative motion between the imaging camera and the detected object. In this paper, we propose a robust wood slice recognition scheme using the low quality color wood slice images with the above-mentioned image blurs. First, a novel 2-D image measurement machine is devised, to obtain the object images sequentially by using a color camera. Second, the image-moment-based blur invariant features are calculated. Third, wood slice recognition is performed by using the computed Euclidean distance based on the moment invariants. We have experimentally proved that the effective use of image blur information improves the recognition accuracy of camera-captured wood slices. Moreover, the allowed maximum translation speed of the moving gallery is also discussed theoretically and experimentally. This scheme can identify the wood species by means of the slice recognition so as to judge the physical property and economic value of different wood species correctly.
Structural optimization of contact electrodes in microbial fuel cells for current density enhancements
12 March 2012, 09:24:04
Publication year: 2012
Source:Sensors and Actuators A: Physical, Volume 177
Shogo Inoue, Erika A. Parra, Adrienne Higa, Yingqi Jiang, Pengbo Wang, Cullen R. Buie, John D. Coates, Liwei Lin
More than 200% current density enhancement in miniaturized microbial fuel cells (MFCs) has been successfully demonstrated by optimizing the contact electrode structure using micro and nano features. Two fundamental issues are addressed in this work: (1) a methodology to enhance current/power density of MFCs by changing micro and nano structural configurations of contact electrodes and (2) a study on the effectiveness of charge transfer between living cells with organic nanowire-pili and micro/nano interfacial electrodes. This paper details the fabrication and characterization processes of miniaturized MFCs with experimental results, and discusses the prospective power density of MFCs using micro/nano processes. Moreover, a hypothesis for the direct electron transport mechanism from living cells to electrodes is experimentally corroborated. As such, this work represents a step toward higher energy conversion efficiency as well as practical applications of MFCs.
Source:Sensors and Actuators A: Physical, Volume 177
Shogo Inoue, Erika A. Parra, Adrienne Higa, Yingqi Jiang, Pengbo Wang, Cullen R. Buie, John D. Coates, Liwei Lin
More than 200% current density enhancement in miniaturized microbial fuel cells (MFCs) has been successfully demonstrated by optimizing the contact electrode structure using micro and nano features. Two fundamental issues are addressed in this work: (1) a methodology to enhance current/power density of MFCs by changing micro and nano structural configurations of contact electrodes and (2) a study on the effectiveness of charge transfer between living cells with organic nanowire-pili and micro/nano interfacial electrodes. This paper details the fabrication and characterization processes of miniaturized MFCs with experimental results, and discusses the prospective power density of MFCs using micro/nano processes. Moreover, a hypothesis for the direct electron transport mechanism from living cells to electrodes is experimentally corroborated. As such, this work represents a step toward higher energy conversion efficiency as well as practical applications of MFCs.
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