Integration of Electroactive Polymers in MEMS Ultrasonic Sensors

2010 ◽  
Vol 2010 (DPC) ◽  
pp. 000643-000670
Author(s):  
Michael Kranz ◽  
Michael Whitley ◽  
Sharon Sanchez ◽  
Michael Allen
Keyword(s):  
Acoustic Waves ◽  
Elevated Temperatures ◽  
Electroactive Polymers ◽  
Mems Devices ◽  
Multiple Systems ◽  
Electroactive Films ◽  
Machine Failure ◽  
Acoustic Emission Sensors ◽  
Institute Of Technology ◽  
Electrical Impulses

The U.S. Army AMRDEC, Stanley Associates, and the Georgia Institute of Technology are developing spectrally sensitive acoustic emission sensors for the detection of various phenomena of interest in Army missiles and assets. Multiple systems would benefit from monitoring the acoustic spectrum and identifying signatures of interest. These would include monitoring sounds external to Unattended Ground Sensors, looking for specific sounds associated with machine failure in a condition-based maintenance scenario, and identifying items that are impacting each other. Potential device designs employ electroactive polymers to convert acoustic waves into electrical impulses. Many electroactive polymers are, however, not compatible with standard MEMS processing, particularly at elevated temperatures. Piezoelectric films, such as PVDF, require stretching and poling processes to orient the crystal structure. Electret films also require poling to create a permanent polarization, plus discharge occurs at relatively low-temperatures. These types of films are difficult to integrate directly into MEMS devices because of these incompatible processes. The films are therefore added using post-fabrication bonding and assembly processes, thus reducing design flexibility and increasing cost. This paper will present techniques being developed to integrate electroactive polymers directly in MEMS sensors as opposed to performing post-fabrication assembly of electroactive films into sensor structures.

scholarly journals Correlation of BAW and SAW properties of langasite at elevated temperatures

2015 ◽  
Vol 4 (2) ◽  
pp. 331-340 ◽  
Author(s):  
M. Schulz ◽  
E. Mayer ◽  
I. Shrena ◽  
D. Eisele ◽  
M. Schmitt ◽  
...  
Keyword(s):  
Acoustic Wave ◽  
Acoustic Waves ◽  
Elevated Temperatures ◽  
Surface Acoustic Waves ◽  
Propagation Loss ◽  
Bulk Acoustic Wave ◽  
Coupling Coefficients ◽  
Data Set ◽  
Acoustic Wave Devices ◽  
Bulk Acoustic Wave Resonators

Abstract. The full set of electromechanical data of langasite (La3Ga5SiO14) is determined in the temperature range from 20 to 900 °C using differently oriented bulk acoustic wave resonators. For data evaluation a physical model of vibration is developed and applied. Thereby, special emphasis is taken on mechanical and electrical losses at high temperatures. The resulting data set is used to calculate the properties of surface acoustic waves. Direct comparison with experimental data such as velocity, coupling coefficients and propagation loss measured using surface acoustic wave devices with two different crystal orientations shows good agreement.

Design, development and performance estimation of 110 kW kinetic heating simulation facilities for material studies–Phase I

2021 ◽  
pp. 17-28
Author(s):  
Aldin Justin sundararaj ◽  
◽  
◽  
◽  
◽  
...  
Keyword(s):  
Heat Flux ◽  
Elevated Temperatures ◽  
Flux Measurement ◽  
Performance Estimation ◽  
Design Development ◽  
High Enthalpy ◽  
Institute Of Technology ◽  
And Performance ◽  
Material Studies ◽  
Infrared Lamps

In this work, a kinetic heating simulation (KHS) facility has been designed, developed and the performance estimation is carried out in Propulsion and High enthalpy lab held at Karunya Institute of Technology and Sciences. The main objective of developing a KHS facility is to study the material characteristics high temperature paints at elevated temperatures. The Kinetic heating simulation facility is developed for 110 kW power rating. The current facility is designed to hold maximum of 105 Infrared lamps with each lamp having a power rating of 1kW. Ceramic lamps are used for heating the specimen. 15 lamps are placed in a bank and each bank can be controlled individually with the help of controlling unit. A total of 7 banks are used in operation of the kinetic heating simulation facility. To estimate the performance of the KHS facility K-type thermocouple are used for feedback as well as to measure temperature. The KHS also has provision for heat flux measurement. Preliminary studies are carried out to estimate the performance of KHS facility for various ranges

Localized, In-Situ Vacuum Measurements For MEMS Packaging

2003 ◽  
Vol 782 ◽  
Author(s):  
Nicholas Moelders ◽  
James T. Daly ◽  
Anton C. Greenwald ◽  
Edward A. Johnson ◽  
Mark P. McNeal
Keyword(s):  
Elevated Temperatures ◽  
Chemical Species ◽  
Optical Emission ◽  
Mems Devices ◽  
Efficient Operation ◽  
Vacuum Level ◽  
Mems Packaging ◽  
Hermetic Packaging ◽  
Invaluable Tool ◽  
Chip Carrier

ABSTRACTMEMS devices have unique packaging considerations compared to conventional semiconductor devices. They tend to have relatively large die size and many architectures cannot tolerate elevated temperatures. Often these devices require a vacuum environment for efficient operation. While advances have been made in hermetic packaging of MEMS devices, vacuum packaging remains elusive. One significant problem in developing vacuum sealing has been the inability to determine, readily and non-destructively, the vacuum level inside the package. We have previously described the development of a silicon MEMS-based chip design, “SensorChip™,” with integrated photonic crystal and reflective optics, which uses narrow-band optical emission and absorption for selective identification of gas and chemical species. Because the power consumption required to maintain a specific temperature is directly related to the vacuum level, these devices effectively serve as microscopic Pirani gauges – local vacuum sensors in the moderate vacuum range (0.01 to 1.0 torr) of interest to MEMS devices. Using the membrane itself as a vacuum gauge during sealing has proven to be an invaluable tool in developing a robust vacuum seal in a leadless chip carrier package. It has enabled us to optimize choice of design, materials and processing.

The Effect of Sample Preparation upon the Fracture Toughness of Microsized TiAl

2005 ◽  
Vol 297-300 ◽  
pp. 2416-2422 ◽  
Author(s):  
T.P. Halford ◽  
D. Rudinal ◽  
Kazuki Takashima ◽  
Yakichi Higo
Keyword(s):  
Fracture Toughness ◽  
Tial Alloy ◽  
Microelectromechanical Systems ◽  
Elevated Temperatures ◽  
Mems Devices ◽  
Testing Methods ◽  
Preparation Methods ◽  
Micro Scale ◽  
Lamellar Orientation ◽  
Toughness Testing

The effective fracture toughness testing of materials intended for application in MicroElectroMechanical Systems (MEMS) devices is required in order to improve understanding of how they may be expected to perform upon the micro scale. γ-TiAl based materials are being considered for application in MEMS devices required to operate at elevated temperatures. The effect of different preparation methods upon resulting fracture toughness and development of testing methods for these devices is therefore of importance. Micro-sized cantilevers of the γ-TiAl alloy “Alloy 7” (Ti-46Al-5Nb-1W) were therefore prepared using either mechanical or chemical final stage polishing and subsequently used to evaluate fracture toughness. The effectiveness of the evaluation of micro-sized samples of γ-TiAl in this manner is considered, as well as the effects of the different processing methods and variations in properties according to lamellar orientation.

Wafer Level Bonding of MEMS Devices Using Ceramic Lids

2005 ◽  
Author(s):  
Thomas S. Dory ◽  
Bill Read ◽  
Leonel R. Arana ◽  
John M. Heck
Keyword(s):  
Elevated Temperatures ◽  
Rf Mems ◽  
Coefficient Of Thermal Expansion ◽  
Hold Time ◽  
Inert Atmosphere ◽  
Mems Devices ◽  
Wafer Level ◽  
The Difference ◽  
Silicon Device ◽  
Packaging Technique

Wafer level bonding of MEMS devices is becoming an important packaging technique for small die. Wafer lid bonding simplifies and provides an economical assembly process. One requirement for RF MEMS devices is a hermetic lid, seal material, and sealing process for device reliability. A challenge of this packaging technique is the difference between the lid material CTE, coefficient of thermal expansion, and the silicon device wafer. We selected low temperature co-fired ceramics, LTCC, to evaluate as a potential MEMS lid material for wafer level bonding. This report covers the use of LTCC ceramic lids having CTE values of 5.5, 4.0, and 3.4ppm with thickness of 0.5 and 0.3mm. Different bonding recipes using an inert atmosphere were developed to manage warpage after bonding. Cooling ramp rates, dwell times at elevated temperatures, and lid scoring methods were investigated. A hold time at an elevated temperature was required for the ceramic lids with higher CTE values. With the low CTE ceramic lids, no hold time was required. We found successful RF MEMS wafer level bonding, WLB, can be achieved using low CTE ceramic lids.

Diamond and Polycrystalline Diamond for MEMS Applications: Simulations and Experiments

1998 ◽  
Vol 546 ◽  
Author(s):  
Tahir Çağin ◽  
Jianwei Che ◽  
Michael N. Gardos ◽  
William A. Goddard
Keyword(s):  
Elevated Temperatures ◽  
Polycrystalline Diamond ◽  
Md Simulations ◽  
Device Fabrication ◽  
Mems Devices ◽  
Diamond Surfaces ◽  
Bearing Materials ◽  
Dependent Potential ◽  
Tribological Characterization ◽  
Silicon Based

AbstractTo date most of the MEMS devices are been based on Silicon. This is due to the technological know-how accumulated on manipulating, machining, manufacturing of Silicon. However, only very few devices involve moving parts. This is because of the rapid wear arising from high friction in these Silicon based systems. Recent tribometric experiments carried out by Gardos on Silicon and polycrystalline diamond show that this rapid wear is caused by a variety of factors, related both to surface chemistry and cohesive energy density of these likely MEMS bearing materials. Therefore, theoretical and tribological characterization of Si and PCD surfaces is essential prior to device fabrication to assure reliable MEMS operation unded various atmospheric environments, especially at elevated temperatures.In this paper, we summarize tribological experiments and theoretical studies of friction and wear processes on diamond surfaces. We studied the atomic friction of diamond (100)-surface employing an extended bond-order-dependent potential for hydrocarbon systems in MD simulations.

Fatigue Testing of microsized samples of γ-TiAl based material

2004 ◽  
Vol 842 ◽  
Author(s):  
Timothy P. Halford ◽  
Kazuki Takashima ◽  
Yakichi Higo
Keyword(s):  
Fatigue Testing ◽  
Ion Beam ◽  
Peak Stress ◽  
High Strength ◽  
Fatigue Behaviour ◽  
International Standards ◽  
Mems Devices ◽  
Micro Electro Mechanical Systems ◽  
Focussed Ion Beam ◽  
Institute Of Technology

ABSTRACTHigh strength γ-TiAl based alloys, such as Ti-46Al-5Nb-1W (Alloy 7), which were originally developed for gas turbine and automotive applications are now being considered for application in Micro Electro Mechanical Systems (MEMS). This requires the evaluation of these materials upon the microscale. As international standards do not currently exist for the evaluation of the mechanical properties of samples with dimensions equivalent to those required by MEMS devices, the development of new methods was required. The method developed here is intended for the fatigue testing of samples measuring ≈ 10μm (B) × 20μm (W) × 40μm (L). This is completed using a machine recently developed at Tokyo Institute of Technology to load samples of lamellar γ-TiAl based material to failure in compressive bending. This method is intended to work alongside methods previously developed for the fracture toughness testing of similar microsized cantilever bend specimens.In this work sample cantilevers of Alloy 7 are Focussed Ion Beam (FIB) machined from foil ≈ 20μm thick and their stress - life (S-N) fatigue behaviour evaluated. The dependence of fatigue life upon lamellar orientation for a given peak stress / stress range is considered. The effect of the reduced scale of these samples upon the mean and scatter of these sample lifetimes is also considered through comparison with previous data obtained from the S-N testing of macrosized samples of the same material.

Characterization of Rare-Earth Fluoride Anti-Stokes Phosphors by Scanning arid Transmission Electron Microscopy

1971 ◽  
Vol 29 ◽  
pp. 142-143
Author(s):  
N. M. P. Low ◽  
L. E. Brosselard
Keyword(s):  
Electron Microscopy ◽  
Rare Earth ◽  
Elevated Temperatures ◽  
Stoichiometric Composition ◽  
Rare Earth Ions ◽  
Crystalline Solid ◽  
Precipitation Process ◽  
Rare Earth Fluoride ◽  
Earth Fluoride ◽  
Rare Earth Fluorides

There has been considerable interest over the past several years in materials capable of converting infrared radiation to visible light by means of sequential excitation in two or more steps. Several rare-earth trifluorides (LaF3, YF3, GdF3, and LuF3) containing a small amount of other trivalent rare-earth ions (Yb3+ and Er3+, or Ho3+, or Tm3+) have been found to exhibit such phenomenon. The methods of preparation of these rare-earth fluorides in the crystalline solid form generally involve a co-precipitation process and a subsequent solid state reaction at elevated temperatures. This investigation was undertaken to examine the morphological features of both the precipitated and the thermally treated fluoride powders by both transmission and scanning electron microscopy.Rare-earth oxides of stoichiometric composition were dissolved in nitric acid and the mixed rare-earth fluoride was then coprecipitated out as fine granules by the addition of excess hydrofluoric acid. The precipitated rare-earth fluorides were washed with water, separated from the aqueous solution, and oven-dried.

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