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Papers from the latest issue:High Temperature Dynamic Viscosity Sensor for Engine Oil Applications
28 October 2011, 20:45:52
Publication year: 2011
Source: Sensors and Actuators A: Physical, Available online 28 October 2011
Matthew Brouwer, Lokesh A. Gupta, Farshid Sadeghi, Dimitrios Peroulis, Douglas Adams
This paper presents a new high temperature dynamic viscosity sensor for in-situ condition monitoring of engine lubricants. The sensor is used to measure the variation in the quality factor of a vibrating piezoelectric cantilever beam due to viscous damping. The sensor was used to measure the dynamic viscosity of various single and multi-grade engines oils up to 180cP from 25°C to 60°C. The sensor is capable of detecting degradation and dilution of engine oil for both new and used samples of 5 W-30 and 10 W-40 and diluted SAE 30 engine oils. All of the viscosity measurements presented are within 0.13% to 9.8% of the results obtained using the standard Walther equation at various temperatures. An equation relating dynamic viscosity of an oil sample to the quality factor of the beam is presented. The quality factor measurement circuit presented in this research can be implemented in automotive applications for in-situ condition monitoring of lubricant viscosity.
Source: Sensors and Actuators A: Physical, Available online 28 October 2011
Matthew Brouwer, Lokesh A. Gupta, Farshid Sadeghi, Dimitrios Peroulis, Douglas Adams
This paper presents a new high temperature dynamic viscosity sensor for in-situ condition monitoring of engine lubricants. The sensor is used to measure the variation in the quality factor of a vibrating piezoelectric cantilever beam due to viscous damping. The sensor was used to measure the dynamic viscosity of various single and multi-grade engines oils up to 180cP from 25°C to 60°C. The sensor is capable of detecting degradation and dilution of engine oil for both new and used samples of 5 W-30 and 10 W-40 and diluted SAE 30 engine oils. All of the viscosity measurements presented are within 0.13% to 9.8% of the results obtained using the standard Walther equation at various temperatures. An equation relating dynamic viscosity of an oil sample to the quality factor of the beam is presented. The quality factor measurement circuit presented in this research can be implemented in automotive applications for in-situ condition monitoring of lubricant viscosity.
Highlights
► Sensor measures dynamic viscosity of various engine oils at temperatures up to 60°C. ► Maximum measurement range for this specific sensor was 180 cP. ► Capable of detecting degradation and dilution of engine oil in-situ.Dependency between amplitude and modeshape on vibrating diaphragms
26 October 2011, 20:40:04
Publication year: 2011
Source: Sensors and Actuators A: Physical, Available online 25 October 2011
Luis Teia Gomes
Two theories governing the vibration of plates were compared: one, considering the amplitude is independent of modeshape (method of separation of variables) and the other, considering it dependent (Lord Rayleighs’ approach). An exhaustive and thorough study was made, both theoretical for an homogeneous diaphragm and experimentally for several piezoelectric diaphragms, showing that Lord Rayleigh's theory is the correct one and that amplitude of vibration is dependent on modeshape through the coupling factor C. To verify this dependency, several equations were graphically compared showing that accounting for C is critical for a correct prediction. Moreover, the meaning of the coupling factor is explained from a mathematical and physical point of view. The theory predicts correctly both qualitatively and quantitatively the vibration of a diaphragm for varying excitation frequency having only as an input the geometrical and physical properties of the diaphragm.
Source: Sensors and Actuators A: Physical, Available online 25 October 2011
Luis Teia Gomes
Two theories governing the vibration of plates were compared: one, considering the amplitude is independent of modeshape (method of separation of variables) and the other, considering it dependent (Lord Rayleighs’ approach). An exhaustive and thorough study was made, both theoretical for an homogeneous diaphragm and experimentally for several piezoelectric diaphragms, showing that Lord Rayleigh's theory is the correct one and that amplitude of vibration is dependent on modeshape through the coupling factor C. To verify this dependency, several equations were graphically compared showing that accounting for C is critical for a correct prediction. Moreover, the meaning of the coupling factor is explained from a mathematical and physical point of view. The theory predicts correctly both qualitatively and quantitatively the vibration of a diaphragm for varying excitation frequency having only as an input the geometrical and physical properties of the diaphragm.
LPG-based optical fibre sensor for acoustic wave detection
26 October 2011, 20:40:04
Publication year: 2011
Source: Sensors and Actuators A: Physical, Available online 25 October 2011
J-O Gaudron, F Surre, T Sun, K.T.V. Grattan
In this work, a long period grating (LPG)-based optical fibre sensor system has been designed and set up, following which it has been evaluated and optimized for acoustic wave detection. The device relies upon the interaction of the acoustic wave with a LPG placed between two pillars (with one being movable) and exposed to a range of representative acoustic waves generated by a loudspeaker placed at a known distance from the sensor thus created. Through determining the response both to the variation of the magnitude and the frequency of the acoustic signals generated by the loudspeaker, the long period grating-based sensor system created has been successfully characterized, showing clear sensitivities to specific acoustic frequencies, irrespective of the signal intensity variations. In addition, these frequencies are found to be closely related to the configuration of the LPG, i.e. the LPG bending curvature created which can be varied, in this laboratory set-up, by changing the distance between the pillars. The experimental results obtained are in good agreement with those obtained from a modified elastic string theory approach, and thus show potential for the use of LPG-based technique for acoustic wave detection in various media,such as fluidsto create a compact and easy to use sensor system.
Source: Sensors and Actuators A: Physical, Available online 25 October 2011
J-O Gaudron, F Surre, T Sun, K.T.V. Grattan
In this work, a long period grating (LPG)-based optical fibre sensor system has been designed and set up, following which it has been evaluated and optimized for acoustic wave detection. The device relies upon the interaction of the acoustic wave with a LPG placed between two pillars (with one being movable) and exposed to a range of representative acoustic waves generated by a loudspeaker placed at a known distance from the sensor thus created. Through determining the response both to the variation of the magnitude and the frequency of the acoustic signals generated by the loudspeaker, the long period grating-based sensor system created has been successfully characterized, showing clear sensitivities to specific acoustic frequencies, irrespective of the signal intensity variations. In addition, these frequencies are found to be closely related to the configuration of the LPG, i.e. the LPG bending curvature created which can be varied, in this laboratory set-up, by changing the distance between the pillars. The experimental results obtained are in good agreement with those obtained from a modified elastic string theory approach, and thus show potential for the use of LPG-based technique for acoustic wave detection in various media,such as fluidsto create a compact and easy to use sensor system.
Enhancing Displacement of Lead-Zirconate-Titanate (PZT) Thin-Film Membrane Microactuators via a Dual Electrode Design
26 October 2011, 20:40:04
Publication year: 2011
Source: Sensors and Actuators A: Physical, Available online 25 October 2011
Chuan Luo, G.Z. Cao, I.Y. Shen
A common design of piezoelectric microactuators adopts a membrane structure that consists of a base silicon diaphragm, a layer of bottom electrode, a layer of piezoelectric thin film, and a layer of top electrode. In particular, the piezoelectric thin film is often made of lead-zirconate-titanate (PZT) for its high piezoelectric constants. When driven electrically, the PZT thin film extends or contracts flexing the membrane and generating an out-of-plane displacement. Many manufacturing defects, however, could significantly reduce the designed actuator displacement. Examples include residual stresses, warping, non-uniform etching of the silicon diaphragm, and misalignment between the top electrode and the silicon diaphragm. The purpose of this paper is to develop a dual top-electrode design to enhance the actuator displacement. In this design, the top electrode consists of two disconnected (thus independent) electrode areas, while a continuous bottom electrode serves as the ground. The two top electrodes are located in two regions with opposite curvature when the diaphragm deflects. When the two top electrodes are driven in an out-of-phase manner, the actuator displacement is enhanced. Finite element analyses and experimental measurements both confirm the feasibility of this design. When manufacturing defects are present, experimental results indicate that the actuator displacement can be optimized by adjusting the phase difference between the dual top electrodes.
Source: Sensors and Actuators A: Physical, Available online 25 October 2011
Chuan Luo, G.Z. Cao, I.Y. Shen
A common design of piezoelectric microactuators adopts a membrane structure that consists of a base silicon diaphragm, a layer of bottom electrode, a layer of piezoelectric thin film, and a layer of top electrode. In particular, the piezoelectric thin film is often made of lead-zirconate-titanate (PZT) for its high piezoelectric constants. When driven electrically, the PZT thin film extends or contracts flexing the membrane and generating an out-of-plane displacement. Many manufacturing defects, however, could significantly reduce the designed actuator displacement. Examples include residual stresses, warping, non-uniform etching of the silicon diaphragm, and misalignment between the top electrode and the silicon diaphragm. The purpose of this paper is to develop a dual top-electrode design to enhance the actuator displacement. In this design, the top electrode consists of two disconnected (thus independent) electrode areas, while a continuous bottom electrode serves as the ground. The two top electrodes are located in two regions with opposite curvature when the diaphragm deflects. When the two top electrodes are driven in an out-of-phase manner, the actuator displacement is enhanced. Finite element analyses and experimental measurements both confirm the feasibility of this design. When manufacturing defects are present, experimental results indicate that the actuator displacement can be optimized by adjusting the phase difference between the dual top electrodes.
Application of Silane-Free Atmospheric-Plasma Silicon Deposition to MEMS Devices
26 October 2011, 20:40:04
Publication year: 2011
Source: Sensors and Actuators A: Physical, Available online 25 October 2011
Yoshinori Yokoyama, Takaaki Murakami, Shinichi Izuo, Yukihisa Yoshida, Toshihiro Itoh
We have developed a silane-free atmospheric-pressure plasma Si deposition process and investigated the properties of the deposited films by fabricating strain gauge type pressure sensors for the first time. The Si deposition process, which is known as plasma-enhanced chemical transport, utilizes the temperature difference between the solid Si source and the substrate in atmospheric hydrogen plasma. The Si films were deposited at a low temperature of 300 °C at 700 Torr. We have clarified that the Si films were composed of poly crystals by X-ray Diffraction (XRD) patterns and Raman spectra. We fabricated strain gauges using the poly-Si films. The gauge factor of approximately 10 was achieved. The bridge voltage of the pressure sensor was found to be proportional to the pressure. The Si films are deemed appropriate for use as MEMS devices.
Source: Sensors and Actuators A: Physical, Available online 25 October 2011
Yoshinori Yokoyama, Takaaki Murakami, Shinichi Izuo, Yukihisa Yoshida, Toshihiro Itoh
We have developed a silane-free atmospheric-pressure plasma Si deposition process and investigated the properties of the deposited films by fabricating strain gauge type pressure sensors for the first time. The Si deposition process, which is known as plasma-enhanced chemical transport, utilizes the temperature difference between the solid Si source and the substrate in atmospheric hydrogen plasma. The Si films were deposited at a low temperature of 300 °C at 700 Torr. We have clarified that the Si films were composed of poly crystals by X-ray Diffraction (XRD) patterns and Raman spectra. We fabricated strain gauges using the poly-Si films. The gauge factor of approximately 10 was achieved. The bridge voltage of the pressure sensor was found to be proportional to the pressure. The Si films are deemed appropriate for use as MEMS devices.
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