Fabrication of High-frequency Piezoelectric Resonant Micro-accelerometers Based on Capacitive Loading Effect PDF Download
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Author: Ankesh Todi
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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In this thesis, a high-frequency resonant accelerometer is presented. This novel sensor was designed to operate in 10’s of MHz frequency range utilizing an out-of-plane capacitive mechanism for acceleration sensing. The sensor is comprised of a 2-port RF MEMS piezoelectric resonator, operating at 27MHz, and a Capacitive Mass-spring structure. One of the resonator ports is electrically connected to the variable capacitor in the mass-spring structure. The acceleration is measured utilizing a piezoelectric stiffening mechanism, where a change in the termination impedance of a piezoelectric resonant body would result in a shift in the resonance frequency of the resonator. The acceleration is extracted from the frequency-modulated output signal of the resonator. The sensors were fabricated on a silicon-on-insulator wafer coated with a thin film of sputtered aluminum nitride as the piezoelectric transducer. Initial test results show a ~600Hz shift in resonance frequency in response to ±1g of acceleration (~300Hz/g sensitivity).
Author: Ankesh Todi
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
In this thesis, a high-frequency resonant accelerometer is presented. This novel sensor was designed to operate in 10’s of MHz frequency range utilizing an out-of-plane capacitive mechanism for acceleration sensing. The sensor is comprised of a 2-port RF MEMS piezoelectric resonator, operating at 27MHz, and a Capacitive Mass-spring structure. One of the resonator ports is electrically connected to the variable capacitor in the mass-spring structure. The acceleration is measured utilizing a piezoelectric stiffening mechanism, where a change in the termination impedance of a piezoelectric resonant body would result in a shift in the resonance frequency of the resonator. The acceleration is extracted from the frequency-modulated output signal of the resonator. The sensors were fabricated on a silicon-on-insulator wafer coated with a thin film of sputtered aluminum nitride as the piezoelectric transducer. Initial test results show a ~600Hz shift in resonance frequency in response to ±1g of acceleration (~300Hz/g sensitivity).
Author: Fatemeh Edalatfar
Publisher:
ISBN:
Category :
Languages : en
Pages : 125
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Book Description
This thesis presents the development of capacitive high-performance accelerometers for sonar wave detection. Two different designs of in-plane and out-of-plane accelerometers are developed, micro-fabricated, and experimentally tested.The out-of-plane accelerometer is designed based on a continuous membrane suspension element. In comparison to beam-type suspension elements, the new design provides uniform displacement of the proof mass, lower cross-axis sensitivity, and lower stress concentration in suspension elements which could result in higher yield in the fabrication process. The out-of-plane accelerometer is fabricated using a novel microfabrication method which facilitates developing continuous membrane type suspension elements and full wafer thick proof mass for accelerometers. The designed accelerometer is fabricated on a silicon-on-insulator wafer with an 8 μm device layer, 1.5 μm buried-oxide layer, and 500 μm handle wafer. The developed accelerometer is proven to have resonance frequency of 5.2 kHz, sensitivity of ~0.9 pF/g, mechanical noise equivalent acceleration of less than 450 ng/√Hz, and an open loop dynamic range of higher than 130 dB while operating at atmospheric pressure.The in-plane single-axis accelerometer is designed based on a proposed mode-tuned modified structure. In this modified structure, the proof mass is substituted with a moving frame which also provides the area for increasing the number of sensing electrodes. This substitution contributes to widening the bandwidth of the accelerometer by locating the anchors and elastic elements both inside and outside of the moving frame. The designed accelerometer is fabricated on a silicon-on-insulator wafer with a 100μm device layer and high aspect ratio capacitive gaps of ~2 μm. The sensitivity of the accelerometer is measured as ~0.7 pF/g with the total noise equivalent acceleration of less than 500 ng/√Hz in the flat band region of the bandwidth. The resonance frequency of the devices is 4.2 kHz while maintaining a linearity of better than 0.7%. The open loop dynamic range of the accelerometer, while operating at atmospheric pressure, is higher than 135 dB, and the cross-axis sensitivity is less than -30 dB.
Author: Tan Tran Duc
Publisher: GRIN Verlag
ISBN: 3640249593
Category : Technology & Engineering
Languages : en
Pages : 83
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Book Description
Diploma Thesis from the year 2005 in the subject Electrotechnology, grade: Master 9.8/10, , language: English, abstract: Microelectromechanical systems (MEMS) are collection of microsensors and actuators that have the ability to sense its environment and react to changes in that environment with the use of a microcircuit control. They also include the conventional microelectronics packaging, integrating antenna structures for command signals into microelectromechanical structures for desired sensing and actuating functions. The system may also need micropower supply, microrelay, and microsignal processing units. Microcomponents make the system faster, more reliable, cheaper, and capable of incorporating more complex functions. In the beginning of 1990s, MEMS appeared with the aid of the development of integrated circuit fabrication processes, in which sensors, actuators, and control functions are co-fabricated in silicon [1]. Since then, remarkable research progresses have been achieved in MEMS under the strong promotions from both government and industries. In addition to the commercialization of some less integrated MEMS devices, such as microaccelerometers, inkjet printer head, micromirrors for projection, etc., the concepts and feasibility of more complex MEMS devices have been proposed and demonstrated for the applications in such varied fields as microfluidics, aerospace, biomedical, chemical analysis, wireless communications, data storage, display, optics, etc. Some branches of MEMS, appearing as microoptoelectromechanical systems (MOEMS), micro total analysis systems, etc., have attracted a great research since their potential applications’ market.
Author: Yong Ping Xu
Publisher: CRC Press
ISBN: 1000793737
Category : Technology & Engineering
Languages : en
Pages : 312
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Book Description
Most MEMS accelerometers on the market today are capacitive accelerometers that are based on the displacement sensing mechanism. This book is intended to cover recent developments of MEMS silicon oscillating accelerometers (SOA), also referred to as MEMS resonant accelerometer. As contrast to the capacitive accelerometer, the MEMS SOA is based on the force sensing mechanism, where the input acceleration is converted to a frequency output. MEMS Silicon Oscillating Accelerometers and Readout Circuits consists of six chapters and covers both MEMS sensor and readout circuit, and provides an in-depth coverage on the design and modelling of the MEMS SOA with several recently reported prototypes. The book is not only useful to researchers and engineers who are familiar with the topic, but also appeals to those who have general interests in MEMS inertial sensors. The book includes extensive references that provide further information on this topic.
Author: Md Sohel Mahmood
Publisher:
ISBN:
Category : Accelerometers
Languages : en
Pages : 156
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Book Description
The work presented in this dissertation describes the design, fabrication and characterization of a Micro Electro Mechanical System (MEMS) capacitive accelerometer on a flexible substrate. To facilitate the bending of the accelerometers and make them mountable on a curved surface, polyimide was used as a flexible substrate. Considering its high glass transition temperature and low thermal expansion coefficient, PI5878G was chosen as the underlying flexible substrate. Three different sizes of accelerometers were designed in CoventorWare® software which utilizes Finite Element Method (FEM) to numerically perform various analyses. Capacitance simulation under acceleration, modal analysis, stress and pull-in study were performed in CoventorWare®. A double layer UV-LIGA technique was deployed to electroplate the proof mass for increased sensitivity. The proof mass of the accelerometers was perforated to lower the damping force as well as to facilitate the ashing process of the underlying sacrificial layer. Three different sizes of accelerometers were fabricated and subsequently characterized. The largest accelerometer demonstrated a sensitivity of 187 fF/g at its resonant frequency of 800 Hz. It also showed excellent noise performance with a signal to noise ratio (SNR) of 100:1. The accelerometers were also placed on curved surfaces having radii of 3.8 cm, 2.5 cm and 2.0 cm for flexibility analysis. The sensitivity of the largest device was obtained to be 168 fF/g on a curved surface of 2.0 cm radius. The radii of robotic index and thumb fingertips are 1.0 cm and 3.5 cm, respectively. Therefore, these accelerometers are fully compatible with robotics as well as prosthetics. The accelerometers were later encapsulated by Kapton® superstrate in vacuum environment. Kapton® is a polyimide film which possesses similar glass transition temperature and thermal expansion coefficient to that of the underlying substrate PI5878G. The thickness of the superstrate was optimized to place the intermediate accelerometer on a plane of zero stress. The Kapton® films were pre-etched before bonding to the device wafer, thus avoiding spin-coating a photoresist layer at high rpm and possibly damaging the already released micro-accelerometers in the device wafer. The packaged accelerometers were characterized in the same way the open accelerometers were characterized on both flat and curved surfaces. After encapsulation, the sensitivity of the largest accelerometer on a flat and a curved surface with 2.0 cm radius were obtained to be 195 fF/g and 174 fF/f, respectively. All three accelerometers demonstrated outstanding noise performance after vacuum packaging with an SNR of 100:1. Further analysis showed that the contribution from the readout circuitry is the most dominant noise component followed by the Brownian noise of the accelerometers. The developed stresses in different layers of the accelerometers upon bending the substrates were analyzed. The stresses in all cases were below the yield strength of the respective layer materials. AlN cantilevers as tactile sensors were also fabricated and characterized on a flexible substrate. Ti was utilized as the bottom and the top electrode for its smaller lattice mismatch to AlN compared to Pt and Al. The piezoelectric layer of AlN was annealed after sputtering which resulted in excellent crystalline orientation. The XRD peak corresponding to AlN (002) plane was obtained at 36.54o. The fabricated AlN cantilevers were capable of sensing pressures from 100 kPa to 850 kPa which includes soft touching of human index finger and grasping of an object. The sensitivities of the cantilevers were between 1.90 × 10-4 V/kPa and 2.04 × 10-4 V/kPa. The stresses inside the AlN and Ti layer, developed upon full bending, were below the yield strength of the respective layer materials.
Author: Mahmoud Rasras
Publisher: MDPI
ISBN: 3038974145
Category : Technology & Engineering
Languages : en
Pages : 252
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Book Description
Micro-electro-mechanical system (MEMS) devices are widely used for inertia, pressure, and ultrasound sensing applications. Research on integrated MEMS technology has undergone extensive development driven by the requirements of a compact footprint, low cost, and increased functionality. Accelerometers are among the most widely used sensors implemented in MEMS technology. MEMS accelerometers are showing a growing presence in almost all industries ranging from automotive to medical. A traditional MEMS accelerometer employs a proof mass suspended to springs, which displaces in response to an external acceleration. A single proof mass can be used for one- or multi-axis sensing. A variety of transduction mechanisms have been used to detect the displacement. They include capacitive, piezoelectric, thermal, tunneling, and optical mechanisms. Capacitive accelerometers are widely used due to their DC measurement interface, thermal stability, reliability, and low cost. However, they are sensitive to electromagnetic field interferences and have poor performance for high-end applications (e.g., precise attitude control for the satellite). Over the past three decades, steady progress has been made in the area of optical accelerometers for high-performance and high-sensitivity applications but several challenges are still to be tackled by researchers and engineers to fully realize opto-mechanical accelerometers, such as chip-scale integration, scaling, low bandwidth, etc. This Special Issue on "MEMS Accelerometers" seeks to highlight research papers, short communications, and review articles that focus on: Novel designs, fabrication platforms, characterization, optimization, and modeling of MEMS accelerometers. Alternative transduction techniques with special emphasis on opto-mechanical sensing. Novel applications employing MEMS accelerometers for consumer electronics, industries, medicine, entertainment, navigation, etc. Multi-physics design tools and methodologies, including MEMS-electronics co-design. Novel accelerometer technologies and 9DoF IMU integration. Multi-accelerometer platforms and their data fusion.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Author:
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Category : Electrical engineering
Languages : en
Pages : 980
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Author: Shekhar Bhansali
Publisher: Elsevier
ISBN: 0857096273
Category : Technology & Engineering
Languages : en
Pages : 511
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Book Description
The application of Micro Electro Mechanical Systems (MEMS) in the biomedical field is leading to a new generation of medical devices. MEMS for biomedical applications reviews the wealth of recent research on fabrication technologies and applications of this exciting technology.The book is divided into four parts: Part one introduces the fundamentals of MEMS for biomedical applications, exploring the microfabrication of polymers and reviewing sensor and actuator mechanisms. Part two describes applications of MEMS for biomedical sensing and diagnostic applications. MEMS for in vivo sensing and electrical impedance spectroscopy are investigated, along with ultrasonic transducers, and lab-on-chip devices. MEMS for tissue engineering and clinical applications are the focus of part three, which considers cell culture and tissue scaffolding devices, BioMEMS for drug delivery and minimally invasive medical procedures. Finally, part four reviews emerging biomedical applications of MEMS, from implantable neuroprobes and ocular implants to cellular microinjection and hybrid MEMS.With its distinguished editors and international team of expert contributors, MEMS for biomedical applications provides an authoritative review for scientists and manufacturers involved in the design and development of medical devices as well as clinicians using this important technology. Reviews the wealth of recent research on fabrication technologies and applications of Micro Electro Mechanical Systems (MEMS) in the biomedical field Introduces the fundamentals of MEMS for biomedical applications, exploring the microfabrication of polymers and reviewing sensor and actuator mechanisms Considers MEMS for biomedical sensing and diagnostic applications, along with MEMS for in vivo sensing and electrical impedance spectroscopy
Author: Minhang Bao
Publisher: Elsevier
ISBN: 008045562X
Category : Technology & Engineering
Languages : en
Pages : 327
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Book Description
Sensors and actuators are now part of our everyday life and appear in many appliances, such as cars, vending machines and washing machines. MEMS (Micro Electro Mechanical Systems) are micro systems consisting of micro mechanical sensors, actuators and micro electronic circuits. A variety of MEMS devices have been developed and many mass produced, but the information on these is widely dispersed in the literature. This book presents the analysis and design principles of MEMS devices. The information is comprehensive, focusing on microdynamics, such as the mechanics of beam and diaphragm structures, air damping and its effect on the motion of mechanical structures. Using practical examples, the author examines problems associated with analysis and design, and solutions are included at the back of the book. The ideal advanced level textbook for graduates, Analysis and Design Principles of MEMS Devices is a suitable source of reference for researchers and engineers in the field. * Presents the analysis and design principles of MEMS devices more systematically than ever before. * Includes the theories essential for the analysis and design of MEMS includes the dynamics of micro mechanical structures * A problem section is included at the end of each chapter with answers provided at the end of the book.
