The Experts below are selected from a list of 1737 Experts worldwide ranked by ideXlab platform
R N Tait - One of the best experts on this subject based on the ideXlab platform.
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fabrication of a silicon micromachined capacitive microphone using a dry etch process
Sensors and Actuators A-physical, 1996Co-Authors: Y B Ning, A W Mitchell, R N TaitAbstract:Abstract A silicon micromachined capacitive microphone has been fabricated on (100) silicon with PECVD silicon nitride as the diaphragm and Backplate material. Amorphous silicon is used as the sacrificial layer and a dry-etch release method is used to free the diaphragm from the Backplate. The dry-etch release method eliminates problems associated with the diaphragm and Backplate sticking together, which often occurs due to capillary force of the rinse liquid with a wet-etch process. The fabricated microphone has a measured capacitance of 9.5 pF and an open-circuit sensitivity of 7 mV Pa −1 at a bias voltage of 6 V. This bias voltage is about 60% of the maximum allowed voltage that will electrostatically pull the diaphragm and Backplate together. The measured frequency response of the microphone is flat within 4 dB from 100 Hz to 10 kHz and shows a gradual increase at higher frequencies.
Gioacchino Miccichè - One of the best experts on this subject based on the ideXlab platform.
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Analysis of the thermomechanical behavior of the IFMIF bayonet target assembly under design loading scenarios
Fusion Engineering and Design, 2015Co-Authors: D. Bernardi, Gioacchino Miccichè, P. Arena, G. Bongiovì, P.a. Di Maio, Manuela Frisoni, M. SerraAbstract:Abstract In the framework of the IFMIF Engineering Validation and Engineering Design Activities (IFMIF/EVEDA) phase, ENEA is responsible for the design of the European concept of the IFMIF lithium target system which foresees the possibility to periodically replace only the most irradiated and thus critical component (i.e., the Backplate) while continuing to operate the rest of the target for a longer period (the so-called bayonet Backplate concept). In this work, the results of the steady state thermomechanical analysis of the IFMIF bayonet target assembly under two different design loading scenarios (a “hot” scenario and a “cold” scenario) are briefly reported highlighting the relevant indications obtained with respect to the fulfillment of the design requirements. In particular, the analyses have shown that in the hot scenario the temperatures reached in the target assembly are within the material acceptable limits while in the cold scenario transition below the ductile to brittle transition temperature (DBTT) cannot be excluded. Moreover, results indicate that the contact between Backplate and high flux test module is avoided and that the overall structural integrity of the system is assured in both scenarios. However, stress linearization analysis reveals that ITER Structural Design Criteria for In-vessel Components (SDC-IC) design rules are not always met along the selected paths at Backplate middle plane section in the hot scenario, thus suggesting the need of a revision of the Backplate design or a change of the operating conditions.
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Engineering design and steady state thermomechanical analysis of the IFMIF European lithium target system
2013 IEEE 25th Symposium on Fusion Engineering (SOFE), 2013Co-Authors: P. Arena, Gioacchino Miccichè, D. Bernardi, G. Bongiovì, P.a. Di Maio, Manuela Frisoni, M. SerraAbstract:In the framework of the current IFMIF Engineering Validation and Engineering Design Activities (IFMIF/EVEDA) phase, ENEA is responsible for the design of the European concept of the IFMIF lithium target system which foresees the possibility to periodically replace only the most irradiated and thus critical component (i.e., the Backplate) while continuing to operate the rest of the target for a longer period (bayonet Backplate concept). In this work, the results of the steady state thermomechanical analysis of the IFMIF EU target assembly are briefly reported highlighting the relevant indications obtained with respect to the fulfillment of the design requirements.
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Enhancement of the remote handling strategy for the refurbishment of the Backplate bayonet concept of IFMIF target system
Fusion Engineering and Design, 2011Co-Authors: Gioacchino Miccichè, D. Bernardi, L. Lorenzelli, V. QueralAbstract:Abstract One of the most technically challenging activities of the IFMIF facility is the maintenance and the refurbishment of its components, and among these the target system appears to be critical since it is located in the most severe region of neutron irradiation (60 dpa/fpy). Two different target assembly systems have been developed: the first is known as integral target while the second one is based on the so called replaceable Backplate bayonet concept. The present remote handling (RH) procedures developed for the refurbishment of the removable Backplate foresee the removal of all the components from the upper part of the test cell. This operation has a strong impact on the intervention time for the Backplate refurbishment which has to be repeated at least every year. Consequently the need to update the RH strategy for the refurbishment of this component becomes a precondition in order to fulfill the stringent requirement to enhance the duty cycle of IFMIF plant. In this paper two potential approaches are presented: the first relies on the possibility to perform all the refurbishment operations in situ in the test cell cavern, whilst the second one foresees to perform these operations off-line in a hot cell. Advantages and disadvantages of these approaches together with the RH requirements for the refurbishment operations of the Backplate bayonet concepts are also reported.
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IFMIF replaceable Backplate: Remote handling activities, rescue procedures and evaluation of a prototype reliability
Fusion Engineering and Design, 2005Co-Authors: Gioacchino Miccichè, G. Collina, L. Muro, B. RiccardiAbstract:Abstract The reference IFMIF target design is based on the use of a replaceable Backplate. The Backplate is the component most heavily exposed to the high neutron flux, and so its lifetime is expected to be very short. Moreover, the high activation levels prevent direct hands-on access to the target components and thus the maintenance work of such target facility has to be performed remotely. A prototype of the replaceable Backplate, based on so-called “ bayonet concept”, has been fabricated and validated and its suitability for the remote handling maintainability has been demonstrated. Furthermore, a cycle of repetitive trials of Backplate replacement were executed to evaluate the reliability of the prototype including rescue procedures. This paper outlines the remote handling activities, the reliability trials carried out and the development of the rescue procedures for the IFMIF target replaceable Backplate. The overall results of the activities are also reported.
Kwang-cheol Lee - One of the best experts on this subject based on the ideXlab platform.
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Double-chip condenser microphone for rigid Backplate using DRIE and wafer bonding technology
Sensors and Actuators A: Physical, 2007Co-Authors: Hyu-sang Kwon, Kwang-cheol LeeAbstract:Abstract A novel silicon condenser microphone with a rigid Backplate has been proposed and fabricated. The Backplate is fabricated on a separated wafer from the membrane to enhance acoustic characteristics, and they are combined together by gold–tin (Au/Sn) eutectic solder bonding. On a 2.5 mm × 2.5 mm, 0.5 μm thick low stress silicon nitride membrane, 2 mm × 2 mm Au/Ni/Cr membrane electrode is deposited including 3 μm thick Au/Sn layer. A 2 mm × 2 mm, 150 μm thick single crystal silicon rigid Backplate has 1.8 mm × 1.8 mm Backplate electrode, and an air gap, which is fabricated by bulk micromachining, and a silicon deep reactive ion etching. Slots and 50–60 μm radius circular acoustic holes to reduce air damping are also formed in the Backplate chip. The fabricated microphone sensitivity is 39.8 μV Pa−1 (−88 dB re. 1 V Pa−1) at 1 kHz using 28 V polarization voltage. The microphone shows flat frequency response within 1 dB from 20 Hz at least up to 5 kHz.
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Fabrication Ofrigid Backplate Condensermicrophone Using Drie and Wafer Bonding Technology
19th IEEE International Conference on Micro Electro Mechanical Systems, 1Co-Authors: Kwang-cheol Lee, Hyu-sang KwonAbstract:This paper presents a novel MEMS condenser microphone with rigid Backplate to enhance acoustic characteristics. The MEMS condenser microphone consists of membrane and Backplate chips which are bonded together by gold-tin (Au/Sn) eutectic solder bonding. The 2 mm × 2 mm, 150-μm-thick Backplate is fabricated using silicon deep reactive ion etching from Backplate wafer, where 50~60-μm radius cylindrical acoustic holes are also fabricated to reduce air damping. The microphone sensitivity is 39.8 μV/Pa (-88 dB re. 1 V/Pa) at 1 kHz and 28 V polarization voltage. The microphone shows flat frequency response within 2 dB between 20 Hz and 5 kHz.
Hyu-sang Kwon - One of the best experts on this subject based on the ideXlab platform.
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Double-chip condenser microphone for rigid Backplate using DRIE and wafer bonding technology
Sensors and Actuators A: Physical, 2007Co-Authors: Hyu-sang Kwon, Kwang-cheol LeeAbstract:Abstract A novel silicon condenser microphone with a rigid Backplate has been proposed and fabricated. The Backplate is fabricated on a separated wafer from the membrane to enhance acoustic characteristics, and they are combined together by gold–tin (Au/Sn) eutectic solder bonding. On a 2.5 mm × 2.5 mm, 0.5 μm thick low stress silicon nitride membrane, 2 mm × 2 mm Au/Ni/Cr membrane electrode is deposited including 3 μm thick Au/Sn layer. A 2 mm × 2 mm, 150 μm thick single crystal silicon rigid Backplate has 1.8 mm × 1.8 mm Backplate electrode, and an air gap, which is fabricated by bulk micromachining, and a silicon deep reactive ion etching. Slots and 50–60 μm radius circular acoustic holes to reduce air damping are also formed in the Backplate chip. The fabricated microphone sensitivity is 39.8 μV Pa−1 (−88 dB re. 1 V Pa−1) at 1 kHz using 28 V polarization voltage. The microphone shows flat frequency response within 1 dB from 20 Hz at least up to 5 kHz.
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Fabrication Ofrigid Backplate Condensermicrophone Using Drie and Wafer Bonding Technology
19th IEEE International Conference on Micro Electro Mechanical Systems, 1Co-Authors: Kwang-cheol Lee, Hyu-sang KwonAbstract:This paper presents a novel MEMS condenser microphone with rigid Backplate to enhance acoustic characteristics. The MEMS condenser microphone consists of membrane and Backplate chips which are bonded together by gold-tin (Au/Sn) eutectic solder bonding. The 2 mm × 2 mm, 150-μm-thick Backplate is fabricated using silicon deep reactive ion etching from Backplate wafer, where 50~60-μm radius cylindrical acoustic holes are also fabricated to reduce air damping. The microphone sensitivity is 39.8 μV/Pa (-88 dB re. 1 V/Pa) at 1 kHz and 28 V polarization voltage. The microphone shows flat frequency response within 2 dB between 20 Hz and 5 kHz.
Claes H. Dohlman - One of the best experts on this subject based on the ideXlab platform.
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Measuring Forward Light Scatter by the Boston Keratoprosthesis in Various Configurations.
Cornea, 2017Co-Authors: Musa Abdelaziz, Claes H. Dohlman, Rony R. SayeghAbstract:PURPOSE Light scatter results in degradation of visual function. An optical bench model was used to identify the origins of scatter in the setting of a Boston keratoprosthesis (KPro). The effect of various modifications in the device design and light-blocking configurations was explored. METHODS A KPro was mounted on a contact lens holder on a bench, and forward light scatter was recorded with a camera attached to a rotating goniometer arm. Scattered light was recorded at different angles for different KPro modifications, and the point-spread function (PSF) curves were recorded. The area under the curve (AUC) was calculated for each PSF curve. RESULTS The isolated KPro optical cylinder in a totally blackened holding lens had a tight PSF (AUC = 3.3). Additional blackening of the walls of the KPro stem did not further diminish forward scatter significantly. If the holding lens is made translucent by sandblasting (to simulate an in vivo carrier cornea) and the KPro is inserted without a Backplate, forward scatter is substantial (AUC = 11.3). If a standard Backplate (with holes) is added, light scatter is considerably reduced regardless of whether the Backplate is made of polymethyl methacrylate or titanium (AUC = 5.3 and 4.4, respectively). Addition of an acrylic intraocular lens behind the KPro (the pseudophakic KPro setup) did not increase scatter. CONCLUSIONS Most of the scattered light in eyes implanted with a KPro originates from the surrounding hazy corneal graft. The standard addition of a Backplate reduces light scatter. There was no difference in forward light scatter between the aphakic and the pseudophakic KPro.
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Titanium back plate for a PMMA keratoprosthesis: clinical outcomes
Graefe's Archive for Clinical and Experimental Ophthalmology, 2011Co-Authors: Amit Todani, Joseph B. Ciolino, Jared D. Ament, Kathryn A. Colby, Roberto Pineda, Michael W. Belin, James V. Aquavella, James Chodosh, Claes H. DohlmanAbstract:Background/Purpose To compare the rate of retroprosthetic membrane (RPM) formation in Boston Keratoprosthesis (BKPro) with polymethyl methacrylate (PMMA) versus titanium Backplates. Design Retrospective comparative chart review. Methods Multicenter study population: a total of 78 eyes with keratoprosthesis implants with either PMMA or titanium Backplates were included in the study. To be included in the study, all subjects had to have completed a minimum of 6-month follow-up period. Incidence of RPM development at 6-month postoperative period was noted across the study population. PMMA and titanium Backplates were then compared by their rate of association with subsequent RPM. Results Twenty-three out of 55 eyes (41.8%) with PMMA Backplates and three out of 23 eyes (13.0%) with titanium Backplates had developed an RPM at 6 months after implantation. The titanium Backplates were associated with significantly less RPM formation than PMMA Backplates ( p = 0.014, Chi-square test). Conclusions Titanium seems to be associated with less RPM formation than PMMA when used as a material for the BKPro back plate.
