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:
Numerical and analytical modelling of holed MEMS resonators
30 December 2011, 02:38:01
Publication year: 2011
Source: Sensors and Actuators A: Physical, Available online 29 December 2011
Y. Civet, F. Casset, J.F. Carpentier, S. Basrour
After consistently progress in Micro-Electro-Mechanical (MEM) resonators, Silicon oscillators are finally being commercialized for time and frequency control applications not requiring huge frequency accuracy. Indeed, they offer size reduction, potentially low cost and CMOS integration. However, frequency shift because of holes, unavoidable for MEMS release or damping effects, is still one of the challenges to address high frequency accuracy applications. In this article, we present the mechanical modelling of holed clamped-clamped (CC) beam resonators. An analytical and a numerical model have been developed to obtain the frequency variations due to holes onto resonant structures. We note a good agreement between both models, presenting less than 1.5% of deviation. We also report the manufacturing of holed clamped-clamped beam resonators in only six major steps using compatible CMOS process. Electrical tests have been performed to check the functionality of our structures. Finally, electrical measurements and analytical model have been compared and a discrepancy less than 0.4% is reported. Analytical models validation enables designers to benefit from a powerful vibrating MEMS design tool, including the influence of holes onto resonant structures for any kinds of applications from sensors to actuators and oscillators.
Source: Sensors and Actuators A: Physical, Available online 29 December 2011
Y. Civet, F. Casset, J.F. Carpentier, S. Basrour
After consistently progress in Micro-Electro-Mechanical (MEM) resonators, Silicon oscillators are finally being commercialized for time and frequency control applications not requiring huge frequency accuracy. Indeed, they offer size reduction, potentially low cost and CMOS integration. However, frequency shift because of holes, unavoidable for MEMS release or damping effects, is still one of the challenges to address high frequency accuracy applications. In this article, we present the mechanical modelling of holed clamped-clamped (CC) beam resonators. An analytical and a numerical model have been developed to obtain the frequency variations due to holes onto resonant structures. We note a good agreement between both models, presenting less than 1.5% of deviation. We also report the manufacturing of holed clamped-clamped beam resonators in only six major steps using compatible CMOS process. Electrical tests have been performed to check the functionality of our structures. Finally, electrical measurements and analytical model have been compared and a discrepancy less than 0.4% is reported. Analytical models validation enables designers to benefit from a powerful vibrating MEMS design tool, including the influence of holes onto resonant structures for any kinds of applications from sensors to actuators and oscillators.
Highlights
► modelling of holed clamped-clamped (CC) beam resonators ► manufacturing of holed clamped-clamped beam resonators in only six major ► Electrical tests performed ► electrical measurements and analytical model have been compared.Physically cross-linked cellulosic gel via 1-butyl-3-methylimidazolium chloride ionic liquid and its electromechanical responses
30 December 2011, 02:38:01
Publication year: 2011
Source: Sensors and Actuators A: Physical, Available online 29 December 2011
Wissawin Kunchornsup, Anuvat Sirivat
Cellulose shows promising piezoelectric properties widely used in electroactive papers (EAPaps), however its solubility still remains a challenging problem. 1-Butyl-3-methylimidazolium Chloride (BMIMCl), a well-known room temperature ionic liquid (RTIL), is utilized here to dissolve a micro-crystalline cellulose. The BMIMCl- cellulose gels are prepared by the solvent casting method. The elctromechanical properties of the cellulose gels are investigated under the oscillatory shear mode at electric field strengths between 0 to 1 kV/mm and as functions of temperature. The storage modulus (Ǵ) increases linearly with temperature up to 333 K at 1 rad/s in the absence of electric field strength. The storage moduli (Ǵ) also increase linearly with temperature up to 313 K at 1 rad/s in the presence of 1 kV/mm of electric field strength and decreases above 313 K, consistent with the behavior of dielectric permittivity (ɛ́). The elastic-plastic-viscous transition is observed in the presence of 1 kV/mm. It is shown that the conditions imposed by electric field strength and temperature alter the transition temperature, and lower the dielectric constant, the storage modulus, and the actuation performance. In the deflection experiments, under applied DC electric field, the deflection distances of the gels linearly increase with increasing electric field strength along with the dielectrophoresis forces above the electrical yield strength of 100 V/mm. The back and forth swinging occurs under the constant electric field strength between 525-550 V/mm due to the competition between the anion and cation movements within the ionic liquid. Electrostatic force microscope (EFM) is then employed to investigate the gel topology and the cationic channel and aggregation that control the actuation behavior. The Phy gel is shown here to be promising for actuator applications over other existing dielectric elastomers studied at a room temperature in terms of the electrical yield strength, the bending angle, the generated dielectrophoresis force, the energy density, the force density, the mechanical power, the power density, Ǵ at 1 rad/s at 0.25% strain, and the relatively high ɛ́r,20Hz.
Source: Sensors and Actuators A: Physical, Available online 29 December 2011
Wissawin Kunchornsup, Anuvat Sirivat
Cellulose shows promising piezoelectric properties widely used in electroactive papers (EAPaps), however its solubility still remains a challenging problem. 1-Butyl-3-methylimidazolium Chloride (BMIMCl), a well-known room temperature ionic liquid (RTIL), is utilized here to dissolve a micro-crystalline cellulose. The BMIMCl- cellulose gels are prepared by the solvent casting method. The elctromechanical properties of the cellulose gels are investigated under the oscillatory shear mode at electric field strengths between 0 to 1 kV/mm and as functions of temperature. The storage modulus (Ǵ) increases linearly with temperature up to 333 K at 1 rad/s in the absence of electric field strength. The storage moduli (Ǵ) also increase linearly with temperature up to 313 K at 1 rad/s in the presence of 1 kV/mm of electric field strength and decreases above 313 K, consistent with the behavior of dielectric permittivity (ɛ́). The elastic-plastic-viscous transition is observed in the presence of 1 kV/mm. It is shown that the conditions imposed by electric field strength and temperature alter the transition temperature, and lower the dielectric constant, the storage modulus, and the actuation performance. In the deflection experiments, under applied DC electric field, the deflection distances of the gels linearly increase with increasing electric field strength along with the dielectrophoresis forces above the electrical yield strength of 100 V/mm. The back and forth swinging occurs under the constant electric field strength between 525-550 V/mm due to the competition between the anion and cation movements within the ionic liquid. Electrostatic force microscope (EFM) is then employed to investigate the gel topology and the cationic channel and aggregation that control the actuation behavior. The Phy gel is shown here to be promising for actuator applications over other existing dielectric elastomers studied at a room temperature in terms of the electrical yield strength, the bending angle, the generated dielectrophoresis force, the energy density, the force density, the mechanical power, the power density, Ǵ at 1 rad/s at 0.25% strain, and the relatively high ɛ́r,20Hz.
Fabrication of Submicron-gap Electrodes by Silicon Volume Expansion for DNA-Detection
30 December 2011, 02:38:01
Publication year: 2011
Source: Sensors and Actuators A: Physical, Available online 29 December 2011
Xuejiao Chen, Jian Zhang, Zhiliang Wang, Qiang Yan
In this paper, submicron-gap electrodes were fabricated by traditional IC technology. The principle involved is based on the silicon volume expansion in the transition from silicon (Si) to silicon dioxide (SiO2) during thermal oxidation. The micron-level silicon electrode gaps were first generated on the silicon wafer by the conventional photolithography followed by deep reactive ion etching process. The thermal oxidation was then conducted to induce silicon volume expansion. As a result, the gap distance can decrease from micron level to submicron or even nanometer level, which depends on the oxidation parameters. Subsequently, the electrical DNA sensor, which can detect theI-Vvariations during DNA hybridization, had been constructed with the interdigitated submicron-gap electrodes. The result shows that the sensitivity of as-fabricated electrodes with 600 nm gap width can reach 2.5 μA/nM. This method may enable the batch-production and low-cost DNA biosensors.
Source: Sensors and Actuators A: Physical, Available online 29 December 2011
Xuejiao Chen, Jian Zhang, Zhiliang Wang, Qiang Yan
In this paper, submicron-gap electrodes were fabricated by traditional IC technology. The principle involved is based on the silicon volume expansion in the transition from silicon (Si) to silicon dioxide (SiO2) during thermal oxidation. The micron-level silicon electrode gaps were first generated on the silicon wafer by the conventional photolithography followed by deep reactive ion etching process. The thermal oxidation was then conducted to induce silicon volume expansion. As a result, the gap distance can decrease from micron level to submicron or even nanometer level, which depends on the oxidation parameters. Subsequently, the electrical DNA sensor, which can detect theI-Vvariations during DNA hybridization, had been constructed with the interdigitated submicron-gap electrodes. The result shows that the sensitivity of as-fabricated electrodes with 600 nm gap width can reach 2.5 μA/nM. This method may enable the batch-production and low-cost DNA biosensors.
Highlights
► The electrodes were fabricated by thermal oxidization and traditional IC process. ► The design concept is to realize submicron-level fabrication by micron-level technology. ► The fabrication technology is simple, reproducible, ingenious, low-cost, high-yield. ► The method can avoid the limitation of lithography and rigorous fabrication condition. ► The as-prepared submicron-gap electrodes have potential for bio-electronic devices.Power Enhancement of Micro Thermoelectric Generators by Microfluidic Heat Transfer Packaging
30 December 2011, 02:38:01
Publication year: 2011
Source: Sensors and Actuators A: Physical, Available online 29 December 2011
N. Wojtas, E. Schwyter, W. Glatz, S. Kühne, W.Escher, ...
This paper reports on the design, fabrication and proof of concept of a multilayer fluidic packaging system enabling an increase in the output power performance of micro thermoelectric generators (μTEGs). The complete integration of the microfluidic heat transfer system (μHTS) with a μTEG is successfully demonstrated.The fabricated prototype is characterized with respect to its thermal and hydrodynamic performance as well as the generated output power. At a very low pumping power of 0.073mW/cm, a heat transfer resistance of 0.74 cmK/W is reached. The assembled device generated up to 1.47mW/cmat an applied temperature difference of 50 K and a fluid flow rate of 0.1l/min. Further system improvements and the potential of the proposed packaging approach are discussed.
Source: Sensors and Actuators A: Physical, Available online 29 December 2011
N. Wojtas, E. Schwyter, W. Glatz, S. Kühne, W.Escher, ...
This paper reports on the design, fabrication and proof of concept of a multilayer fluidic packaging system enabling an increase in the output power performance of micro thermoelectric generators (μTEGs). The complete integration of the microfluidic heat transfer system (μHTS) with a μTEG is successfully demonstrated.The fabricated prototype is characterized with respect to its thermal and hydrodynamic performance as well as the generated output power. At a very low pumping power of 0.073mW/cm, a heat transfer resistance of 0.74 cmK/W is reached. The assembled device generated up to 1.47mW/cmat an applied temperature difference of 50 K and a fluid flow rate of 0.1l/min. Further system improvements and the potential of the proposed packaging approach are discussed.
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