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Papers by Ryan Knight

Research paper thumbnail of A Novel Vacuum Packaging Design Process for Microelectromechanical System (MEMS) Quad-Mass Gyroscopes

: Gyroscopes are an integral component of inertial measurement units. They are important to Army ... more : Gyroscopes are an integral component of inertial measurement units. They are important to Army systems as they provide Soldiers with information on position, navigation, and timing. The majority of microelectromechanical system (MEMS) gyroscopes in production today are vibratory rate gyroscopes, making them resonant systems. Of the various systematic performance parameters for resonant systems, the quality factor (Q-factor) is an important measure. Q-factor for resonant MEMS such as the quadruple-mass gyroscope (QMG) strongly depends on the pressure at which the system operates. To improve upon Q-factor of the existing MEMS gyroscope, a novel submilliTorr vacuum packaging approach was designed. The packaging process has been broken down into systematic steps with the goal in each step to reduce internal packaging pressure, which was measured using commercial off-the-shelf Pirani gauges. The process was then tested on in-house fabricated QMGs, where Q-factor was measured for both s...

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Research paper thumbnail of Microelectromechanical System (MEMS) Gyroscope Noise Analysis and Scale Factor Characterization over Temperature Variation

: Positioning, navigation, and timing estimation are critically important to Army systems from mu... more : Positioning, navigation, and timing estimation are critically important to Army systems from munitions to mounted and dismounted Soldiers. Gyroscopes provide information about angular orientation and are thus a necessary part of inertial measurement units for navigation systems. Because of noise and temperature changes, the sensor output can drift until the sensor data are no longer correlated to the systems orientation. If sensors provide inaccurate information, the location and orientation of the system are essentially unknown. To determine the reliability of gyroscopes orientation information, we created methodologies to experimentally test and evaluate current and developing microelectromechanical system gyroscopes. The methodologies evaluate key metrics including angle random walk, bias instability, bias, and scale factor, and determine how each metric changes with environmental temperature. The results were verified by testing a commercial off-the-shelf gyroscope. These prog...

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Research paper thumbnail of The analysis and testing of MEMS and macro scale piezoelectric devices

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Research paper thumbnail of Non-Destructive Damping Measurement for Wafer-Level Packaged Microelectromechanical System (MEMS) Acceleration Switches

: Microelectromechanical systems (MEMS) three-axis acceleration threshold sensors have been devel... more : Microelectromechanical systems (MEMS) three-axis acceleration threshold sensors have been developed to measure acceleration threshold levels using voltage switching when the threshold is reached. Determining damping coefficients is important for categorizing how each threshold sensor or switch operates. Switches with different damping coefficients result in different mechanical impedances and response times. Analytical and numerical methods to model damping coefficient values based on empirical data are needed to characterize three-axis acceleration sensors; traditional methods use the displacement of an underdamped system to calculate the damping ratio. Mechanical switches are single output devices that distinguish whether closure occurs or not and lack a transduction mechanism to turn acceleration into a readable displacement signal. Thus, we have devised a more inventive technique to analyze a closed switch. A shock table and vibration testing produces a deterministic accelerat...

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Research paper thumbnail of Non-inertial safe and arm device

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Research paper thumbnail of Tuning of sol-gel derived PZT MEMS resonators

Journal of Micromechanics and Microengineering, Dec 1, 2010

... Ryan R Knight1, Amanda A Frederick1, Changki Mo2 and William W Clark1 ... In this paper, with... more ... Ryan R Knight1, Amanda A Frederick1, Changki Mo2 and William W Clark1 ... In this paper, with sol–gel PZT processing, thin-film MEMS beams with interdigitated electrodes (IDE) were fabricated and tested to examine and demonstrate the tunability of the resonant frequencies. ...

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Research paper thumbnail of MEMS interdigitated electrode pattern optimization for a unimorph piezoelectric beam

Journal of Electroceramics, 2011

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Research paper thumbnail of Electro-mechanical fuze for hand grenades

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Research paper thumbnail of Fabrication and Energy Harvesting Measurements of Vibrating MEMS Piezoelectric Benders

Journal of Vibration and Acoustics-Transactions of the Asme, 2011

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Research paper thumbnail of Finite element analysis of unimorph rectangular piezoelectric diaphragm actuators with experimental verification

Smart Materials and Structures, 2012

This paper presents a study in which the behavior of clamped unimorph rectangular piezoelectric d... more This paper presents a study in which the behavior of clamped unimorph rectangular piezoelectric diaphragms is analyzed and the importance of electrode patterning for enhancement of static displacement is examined. Previous work showed that by regrouping the electrode pattern of a clamped-circular diaphragm actuator the maximum static deflection increased by nearly an order of magnitude in response to an electric

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Research paper thumbnail of Energy Harvesting by Vibrations With MEMS Piezoelectric Benders

ABSTRACT Piezoelectric micro benders are fabricated and tested to demonstrate energy generating p... more ABSTRACT Piezoelectric micro benders are fabricated and tested to demonstrate energy generating performance. Trapezoidal and diagonal unimorph PZT benders with an interdigitated electrode pattern are utilized. The d33 mode design is beneficial for the micro energy harvesting devices because it can generate higher voltage than that of the d31 mode design. It can also eliminate a bottom electrode by only using an interdigitated top electrode which facilitates fabrication, as opposed to the d31 mode design that requires both top and bottom electrodes. The MEMS benders consist of layers of SiO2 /SiNx /ZrO2 /PZT, and a top Au/Cr interdigitated electrode. The experimental results indicate that the fundamental frequencies of the micro benders are about 9.1 kHz for the trapezoidal bender and 18.48 kHz for the diagonal bender, respectively. The micro trapezoidal bender can generate power of approximately 1.4μW into a 680 kΩ resistive load at the resonant frequency. The diagonal bender can generate power of about 18.2 μW into a 100 kΩ resistive load at the resonant frequency.

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Research paper thumbnail of A Novel Vacuum Packaging Design Process for Microelectromechanical System (MEMS) Quad-Mass Gyroscopes

: Gyroscopes are an integral component of inertial measurement units. They are important to Army ... more : Gyroscopes are an integral component of inertial measurement units. They are important to Army systems as they provide Soldiers with information on position, navigation, and timing. The majority of microelectromechanical system (MEMS) gyroscopes in production today are vibratory rate gyroscopes, making them resonant systems. Of the various systematic performance parameters for resonant systems, the quality factor (Q-factor) is an important measure. Q-factor for resonant MEMS such as the quadruple-mass gyroscope (QMG) strongly depends on the pressure at which the system operates. To improve upon Q-factor of the existing MEMS gyroscope, a novel submilliTorr vacuum packaging approach was designed. The packaging process has been broken down into systematic steps with the goal in each step to reduce internal packaging pressure, which was measured using commercial off-the-shelf Pirani gauges. The process was then tested on in-house fabricated QMGs, where Q-factor was measured for both s...

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Research paper thumbnail of Microelectromechanical System (MEMS) Gyroscope Noise Analysis and Scale Factor Characterization over Temperature Variation

: Positioning, navigation, and timing estimation are critically important to Army systems from mu... more : Positioning, navigation, and timing estimation are critically important to Army systems from munitions to mounted and dismounted Soldiers. Gyroscopes provide information about angular orientation and are thus a necessary part of inertial measurement units for navigation systems. Because of noise and temperature changes, the sensor output can drift until the sensor data are no longer correlated to the systems orientation. If sensors provide inaccurate information, the location and orientation of the system are essentially unknown. To determine the reliability of gyroscopes orientation information, we created methodologies to experimentally test and evaluate current and developing microelectromechanical system gyroscopes. The methodologies evaluate key metrics including angle random walk, bias instability, bias, and scale factor, and determine how each metric changes with environmental temperature. The results were verified by testing a commercial off-the-shelf gyroscope. These prog...

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Research paper thumbnail of The analysis and testing of MEMS and macro scale piezoelectric devices

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Research paper thumbnail of Non-Destructive Damping Measurement for Wafer-Level Packaged Microelectromechanical System (MEMS) Acceleration Switches

: Microelectromechanical systems (MEMS) three-axis acceleration threshold sensors have been devel... more : Microelectromechanical systems (MEMS) three-axis acceleration threshold sensors have been developed to measure acceleration threshold levels using voltage switching when the threshold is reached. Determining damping coefficients is important for categorizing how each threshold sensor or switch operates. Switches with different damping coefficients result in different mechanical impedances and response times. Analytical and numerical methods to model damping coefficient values based on empirical data are needed to characterize three-axis acceleration sensors; traditional methods use the displacement of an underdamped system to calculate the damping ratio. Mechanical switches are single output devices that distinguish whether closure occurs or not and lack a transduction mechanism to turn acceleration into a readable displacement signal. Thus, we have devised a more inventive technique to analyze a closed switch. A shock table and vibration testing produces a deterministic accelerat...

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Research paper thumbnail of Non-inertial safe and arm device

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Research paper thumbnail of Tuning of sol-gel derived PZT MEMS resonators

Journal of Micromechanics and Microengineering, Dec 1, 2010

... Ryan R Knight1, Amanda A Frederick1, Changki Mo2 and William W Clark1 ... In this paper, with... more ... Ryan R Knight1, Amanda A Frederick1, Changki Mo2 and William W Clark1 ... In this paper, with sol–gel PZT processing, thin-film MEMS beams with interdigitated electrodes (IDE) were fabricated and tested to examine and demonstrate the tunability of the resonant frequencies. ...

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Research paper thumbnail of MEMS interdigitated electrode pattern optimization for a unimorph piezoelectric beam

Journal of Electroceramics, 2011

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Research paper thumbnail of Electro-mechanical fuze for hand grenades

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Research paper thumbnail of Fabrication and Energy Harvesting Measurements of Vibrating MEMS Piezoelectric Benders

Journal of Vibration and Acoustics-Transactions of the Asme, 2011

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Research paper thumbnail of Finite element analysis of unimorph rectangular piezoelectric diaphragm actuators with experimental verification

Smart Materials and Structures, 2012

This paper presents a study in which the behavior of clamped unimorph rectangular piezoelectric d... more This paper presents a study in which the behavior of clamped unimorph rectangular piezoelectric diaphragms is analyzed and the importance of electrode patterning for enhancement of static displacement is examined. Previous work showed that by regrouping the electrode pattern of a clamped-circular diaphragm actuator the maximum static deflection increased by nearly an order of magnitude in response to an electric

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Energy Harvesting by Vibrations With MEMS Piezoelectric Benders

ABSTRACT Piezoelectric micro benders are fabricated and tested to demonstrate energy generating p... more ABSTRACT Piezoelectric micro benders are fabricated and tested to demonstrate energy generating performance. Trapezoidal and diagonal unimorph PZT benders with an interdigitated electrode pattern are utilized. The d33 mode design is beneficial for the micro energy harvesting devices because it can generate higher voltage than that of the d31 mode design. It can also eliminate a bottom electrode by only using an interdigitated top electrode which facilitates fabrication, as opposed to the d31 mode design that requires both top and bottom electrodes. The MEMS benders consist of layers of SiO2 /SiNx /ZrO2 /PZT, and a top Au/Cr interdigitated electrode. The experimental results indicate that the fundamental frequencies of the micro benders are about 9.1 kHz for the trapezoidal bender and 18.48 kHz for the diagonal bender, respectively. The micro trapezoidal bender can generate power of approximately 1.4μW into a 680 kΩ resistive load at the resonant frequency. The diagonal bender can generate power of about 18.2 μW into a 100 kΩ resistive load at the resonant frequency.

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