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A series of coaxial magnetic pendulums is studied as a simple physical surrogate for more general nonlinearly-coupled almost-identical resonators that arise in quantum communications and the dynamics of social networks. The equations of motion for a series of coaxial magnetic pendulums are derived and the solution is compared to experimental results. The equilibrium points and their stability are also determined.
Razieh Saeidi Hosseini; Glenn R. Heppler; Eihab Abdel-Rahman. Derivation and Experimental Validation of the Equations of Motion of Magnetic Pendulums. ASME Letters in Dynamic Systems and Control 2021, 1 -7.
AMA StyleRazieh Saeidi Hosseini, Glenn R. Heppler, Eihab Abdel-Rahman. Derivation and Experimental Validation of the Equations of Motion of Magnetic Pendulums. ASME Letters in Dynamic Systems and Control. 2021; ():1-7.
Chicago/Turabian StyleRazieh Saeidi Hosseini; Glenn R. Heppler; Eihab Abdel-Rahman. 2021. "Derivation and Experimental Validation of the Equations of Motion of Magnetic Pendulums." ASME Letters in Dynamic Systems and Control , no. : 1-7.
We present a novel electric permittivity sensor based on Bleustein–Gulyaev (BG) waves. Toward that end, we formulate the nonlinear electromechanical partial differential equations governing a BG wave resonator. We find that the permittivity of the material-under-test changes the sensor natural frequencies, thereby enabling the implementation of a frequency-shift permittivity sensor. We also find that the sensor sensitivity is enhanced by increasing bias voltage to drive the sensor into the nonlinear regime. Bias was found to be limited by electrical breakdown. The sensor was fabricated by depositing aluminum electrodes on a shear-poled lead zirconate titanate piezoelectric substrate. Experimental measurements of the displacement on the sensor surface were in good agreement with the developed model.
Alaa Elhady; Mohamed Basha; Eihab M. Abdel-Rahman. Analysis of tunable Bleustein–Gulyaev permittivity sensors. Journal of Applied Physics 2021, 129, 164501 .
AMA StyleAlaa Elhady, Mohamed Basha, Eihab M. Abdel-Rahman. Analysis of tunable Bleustein–Gulyaev permittivity sensors. Journal of Applied Physics. 2021; 129 (16):164501.
Chicago/Turabian StyleAlaa Elhady; Mohamed Basha; Eihab M. Abdel-Rahman. 2021. "Analysis of tunable Bleustein–Gulyaev permittivity sensors." Journal of Applied Physics 129, no. 16: 164501.
This paper offers a critical overview of recent advancements in aqueous sensors for heavy metals. The paper focuses on the challenges and advantages of using microelectromechanical systems (MEMS) sensors in aqueous environments, as well as technical considerations for choosing appropriate polymeric sensing materials. In addition, general considerations and recommendations are included for developing MEMS chemical sensors. These considerations centre around the chemical nature of the target analyte and the environment of the sensor application. By following these recommendations and taking the time to design a suitable sensor and sensing material for the target application instead of a trial‐and‐error approach, it is possible to save both time and cost.
Katherine M. E. Stewart; Majed Al‐Ghamdi; Mahmoud Khater; Eihab M. Abdel‐Rahman; Alexander Penlidis. An overview of sensors and sensing materials for heavy metals in aqueous environments. The Canadian Journal of Chemical Engineering 2021, 1 .
AMA StyleKatherine M. E. Stewart, Majed Al‐Ghamdi, Mahmoud Khater, Eihab M. Abdel‐Rahman, Alexander Penlidis. An overview of sensors and sensing materials for heavy metals in aqueous environments. The Canadian Journal of Chemical Engineering. 2021; ():1.
Chicago/Turabian StyleKatherine M. E. Stewart; Majed Al‐Ghamdi; Mahmoud Khater; Eihab M. Abdel‐Rahman; Alexander Penlidis. 2021. "An overview of sensors and sensing materials for heavy metals in aqueous environments." The Canadian Journal of Chemical Engineering , no. : 1.
We developed a new technique for the detection of shear horizontal surface acoustic waves (SH-SAW) using a one-dimensional laser-based Doppler vibrometer. It measures the out-of-plane surface deformation at the fingertip of an interdigitated transducer (the boundary of the wave aperture) and uses it to estimate the instantaneous in-plane displacement field given the substrate Poisson ratio. It can also estimate the degree of surface confinement (wave decay rate). The proposed approach was first verified using finite element analysis (FEA) and demonstrated experimentally using a Bleustein–Gulyaev resonator.
Alaa Elhady; Eihab Abdel-Rahman. Characterization of Shear Horizontal Waves Using a 1D Laser Doppler Vibrometer. Sensors 2021, 21, 2467 .
AMA StyleAlaa Elhady, Eihab Abdel-Rahman. Characterization of Shear Horizontal Waves Using a 1D Laser Doppler Vibrometer. Sensors. 2021; 21 (7):2467.
Chicago/Turabian StyleAlaa Elhady; Eihab Abdel-Rahman. 2021. "Characterization of Shear Horizontal Waves Using a 1D Laser Doppler Vibrometer." Sensors 21, no. 7: 2467.
We investigate the potential of electrostatic initially curved microbeams to serve as bifurcation gas sensors. Toward that end, we develop static and dynamic reduced-order models of those beams and investigate their nonlinear response. Unlike many models, ours takes into account naturally occurring asymmetries present in fabricated microbeams. We conduct a detailed analysis of the nonlinear dynamics of arch beams focused on their exploitation for inertial sensing applications. The static response reveals that accounting for asymmetry replaces the saddle-node bifurcation, where snap-back occurs, with a symmetry-breaking bifurcation and reduced the voltage range for bistability. The dynamic analysis shows that a symmetry-breaking bifurcation precludes dynamic snap-through in the vicinity of superharmonic resonance, thereby significantly reducing the amplitude of those oscillations. It also shows evidence of a period-doubling bifurcation route to chaos in the vicinity of primary resonance. Based on these findings, we present a novel phase-based bifurcation gas sensor. The proposed detection mechanism allows, for the first time, the use of transition from regular periodic to chaotic motions in inertial sensing of gases. The sensor operation point is set close to the cyclic-fold bifurcation in the vicinity of primary resonance. When mass added by gas immobilization on the detector layer exceeds a threshold, the sensor oscillations abruptly transition from regular periodic motions to chaotic motions. This change can be detected by monitoring the response phase angle as it undergoes a major shift from slow variation within a limited range to fast variation over the full range due to the stretching and folding of the chaotic attractor. The proposed detection mechanism allows the sensor to operate in binary (digital) and analog modes. This is achieved by evaluating the RMS of the response phase angle \(\bar{\varphi }\) and using it to either detect a gas concentration in excess of a safe threshold as an abrupt jump in \(\bar{\varphi }\) or via a calibration curve relating \(\bar{\varphi }\) to the gas concentration. The minimum detectable mass of the sensor is found to be 120 pg.
F. Najar; M. Ghommem; E. Abdel-Rahman. Arch microbeam bifurcation gas sensors. Nonlinear Dynamics 2021, 104, 923 -940.
AMA StyleF. Najar, M. Ghommem, E. Abdel-Rahman. Arch microbeam bifurcation gas sensors. Nonlinear Dynamics. 2021; 104 (2):923-940.
Chicago/Turabian StyleF. Najar; M. Ghommem; E. Abdel-Rahman. 2021. "Arch microbeam bifurcation gas sensors." Nonlinear Dynamics 104, no. 2: 923-940.
Physically demanding and repetitive tasks expose workers to work-related musculoskeletal disorders (WMSDs). Over the last few decades, various rule-based postural assessment systems have been developed and widely used to facilitate the measurement and evaluation of risks related to WMSDs in many industries. However, the applicability of rule-based assessment to tasks involving heavy material handling has not yet been examined. This study investigated the applicability of three rule-based assessment systems (RULA, REBA, and OWAS) to a bricklaying task. To achieve this goal, an automated assessment tool was developed to implement those systems on whole-body data sets consisting of static postures captured by wearable inertial measurement unit suits. The study demonstrates the use of this tool in assessing risk levels (grand scores) encountered by 43 masons during the laying of 16.6-kg concrete masonry units (CMUs) in a standard wall. Furthermore, the biomechanical analysis of the same data set was carried out and utilized as ground truth to evaluate those results. It was found that rule-based assessment may lead to erroneously inflated risk evaluation in heavy manual handling tasks. In contrast, biomechanical analysis provided sensitive risk evaluations that distinguish the different degrees of risk arising from different motion patterns while participants performed the same tasks. These findings suggest using biomechanical analysis as an objective and robust method to evaluate risks encountered in tasks involving heavy material handling.
Juhyeong Ryu; Mohsen M. Diraneyya; Carl T. Haas; Eihab Abdel-Rahman. Analysis of the Limits of Automated Rule-Based Ergonomic Assessment in Bricklaying. Journal of Construction Engineering and Management 2021, 147, 04020163 .
AMA StyleJuhyeong Ryu, Mohsen M. Diraneyya, Carl T. Haas, Eihab Abdel-Rahman. Analysis of the Limits of Automated Rule-Based Ergonomic Assessment in Bricklaying. Journal of Construction Engineering and Management. 2021; 147 (2):04020163.
Chicago/Turabian StyleJuhyeong Ryu; Mohsen M. Diraneyya; Carl T. Haas; Eihab Abdel-Rahman. 2021. "Analysis of the Limits of Automated Rule-Based Ergonomic Assessment in Bricklaying." Journal of Construction Engineering and Management 147, no. 2: 04020163.
This work presents an approach to delay-based reservoir computing (RC) at the sensor level without input modulation. It employs a time-multiplexed bias to maintain transience while utilizing either an electrical signal or an environmental signal (such as acceleration) as an unmodulated input signal. The proposed approach enables RC carried out by sufficiently nonlinear sensory elements, as we demonstrate using a single electrostatically actuated microelectromechanical system (MEMS) device. The MEMS sensor can perform colocalized sensing and computing with fewer electronics than traditional RC elements at the RC input (such as analog-to-digital and digital-to-analog converters). The performance of the MEMS RC is evaluated experimentally using a simple classification task, in which the MEMS device differentiates between the profiles of two signal waveforms. The signal waveforms are chosen to be either electrical waveforms or acceleration waveforms. The classification accuracy of the presented MEMS RC scheme is found to be over 99%. Furthermore, the scheme is found to enable flexible virtual node probing rates, allowing for up to 4× slower probing rates, which relaxes the requirements on the system for reservoir signal sampling. Finally, our experiments show a noise-resistance capability for our MEMS RC scheme.
Mohammad H Hasan; Ali Al-Ramini; Eihab Abdel-Rahman; Roozbeh Jafari; Fadi Alsaleem. Colocalized Sensing and Intelligent Computing in Micro-Sensors. Sensors 2020, 20, 6346 .
AMA StyleMohammad H Hasan, Ali Al-Ramini, Eihab Abdel-Rahman, Roozbeh Jafari, Fadi Alsaleem. Colocalized Sensing and Intelligent Computing in Micro-Sensors. Sensors. 2020; 20 (21):6346.
Chicago/Turabian StyleMohammad H Hasan; Ali Al-Ramini; Eihab Abdel-Rahman; Roozbeh Jafari; Fadi Alsaleem. 2020. "Colocalized Sensing and Intelligent Computing in Micro-Sensors." Sensors 20, no. 21: 6346.
Noise induced motions are a significant source of uncertainty in the response of micro-electro-mechanical systems (MEMS). This is particularly the case for electrostatic MEMS where electrical and mechanical sources contribute to noise and can result in sudden and drastic loss of stability. This paper investigates the effects of noise processes on the stability of electrostatic MEMS via a lumped-mass model that accounts for uncertainty in mass, mechanical restoring force, bias voltage, and AC voltage amplitude. We evaluated the stationary probability density function (PDF) of the resonator response and its basins of attraction in the presence noise and compared them to that those obtained under deterministic excitations only. We found that the presence of noise was most significant in the vicinity of resonance. Even low noise intensity levels caused stochastic jumps between co-existing orbits away from bifurcation points. Moderate noise intensity levels were found to destroy the basins of attraction of the larger orbits. Higher noise intensity levels were found to destroy the basins of attraction of smaller orbits, dominate the dynamic response, and occasionally lead to pull-in. The probabilities of pull-in of the resonator under different noise intensity level are calculated, which are sensitive to the initial conditions.
Yan Qiao; Wei Xu; Hongxia Zhang; Qin Guo; Eihab Abdel-Rahman. A Study of Noise Impact On the Stability of Electrostatic MEMS. Journal of Computational and Nonlinear Dynamics 2020, 15, 1 .
AMA StyleYan Qiao, Wei Xu, Hongxia Zhang, Qin Guo, Eihab Abdel-Rahman. A Study of Noise Impact On the Stability of Electrostatic MEMS. Journal of Computational and Nonlinear Dynamics. 2020; 15 (11):1.
Chicago/Turabian StyleYan Qiao; Wei Xu; Hongxia Zhang; Qin Guo; Eihab Abdel-Rahman. 2020. "A Study of Noise Impact On the Stability of Electrostatic MEMS." Journal of Computational and Nonlinear Dynamics 15, no. 11: 1.
Juhyeong Ryu; Abdullatif Alwasel; Carl T. Haas; Eihab Abdel-Rahman. Analysis of Relationships between Body Load and Training, Work Methods, and Work Rate: Overcoming the Novice Mason’s Risk Hump. Journal of Construction Engineering and Management 2020, 146, 04020097 .
AMA StyleJuhyeong Ryu, Abdullatif Alwasel, Carl T. Haas, Eihab Abdel-Rahman. Analysis of Relationships between Body Load and Training, Work Methods, and Work Rate: Overcoming the Novice Mason’s Risk Hump. Journal of Construction Engineering and Management. 2020; 146 (8):04020097.
Chicago/Turabian StyleJuhyeong Ryu; Abdullatif Alwasel; Carl T. Haas; Eihab Abdel-Rahman. 2020. "Analysis of Relationships between Body Load and Training, Work Methods, and Work Rate: Overcoming the Novice Mason’s Risk Hump." Journal of Construction Engineering and Management 146, no. 8: 04020097.
We present a unified model of electrostatic sensors comprising cantilever microbeam resonators in fluid media. The model couples Euler–Bernoulli beam equation to the nonlinear Reynolds equation. Static, damped eigenvalue, and dynamic reduced-order models were developed and validated by comparing a nonlinear frequency response of a gas sensor to its experimentally measured counterpart. Experiments were conducted to verify the capability of the developed model to predict the out-of-plane and in-plane natural frequencies of the sensor. The models were also used to investigate the potential operation of electrostatic chemical sensors based on different sensing mechanisms. While in-plane and out-of-plane vibration modes were found to be viable alternatives for resonant gas sensors, only in-plane modes were suitable to implement resonant chemical sensors due to the added mass and damping of liquid media. Similarly, higher-order modes were found more sensitive than lower order modes. Further, evidence was found for elastic interaction between out-of-plane modes and liquids in the channel underneath them but none for in-plane modes. Finally, the model predicts that in-plane modes provide the multi-valuedness necessary to implement bifurcation chemical sensors in liquid media.
Mehdi Ghommem; Fehmi Najar; Mohamed Arabi; Eihab Abdel-Rahman; Mustafa Yavuz. A unified model for electrostatic sensors in fluid media. Nonlinear Dynamics 2020, 101, 271 -291.
AMA StyleMehdi Ghommem, Fehmi Najar, Mohamed Arabi, Eihab Abdel-Rahman, Mustafa Yavuz. A unified model for electrostatic sensors in fluid media. Nonlinear Dynamics. 2020; 101 (1):271-291.
Chicago/Turabian StyleMehdi Ghommem; Fehmi Najar; Mohamed Arabi; Eihab Abdel-Rahman; Mustafa Yavuz. 2020. "A unified model for electrostatic sensors in fluid media." Nonlinear Dynamics 101, no. 1: 271-291.
We report a technique to measure in-plane and out-of-plane motions of MEMS using typical out-of-plane (single-axis) Laser Doppler Vibrometers (LDVs). The efficacy of the technique is demonstrated by evaluating the in-plane and out-of-plane modal response and frequency response of an interdigitated comb-drive actuator. We also investigate the validity of observing planar modes of vibration outside their dominant plane of motion and find that it leads to erroneous results. Planar modes must be evaluated in their plan of motion.
Mohamed Arabi; Mary Gopanchuk; Eihab Abdel-Rahman; Mustafa Yavuz. Measurement of In-Plane Motions in MEMS. Sensors 2020, 20, 3594 .
AMA StyleMohamed Arabi, Mary Gopanchuk, Eihab Abdel-Rahman, Mustafa Yavuz. Measurement of In-Plane Motions in MEMS. Sensors. 2020; 20 (12):3594.
Chicago/Turabian StyleMohamed Arabi; Mary Gopanchuk; Eihab Abdel-Rahman; Mustafa Yavuz. 2020. "Measurement of In-Plane Motions in MEMS." Sensors 20, no. 12: 3594.
This paper investigates the responses of initially curved micro-beams subjected to an electrostatic excitation. A Euler-Bernoulli beam theory is utilized to derive the governing equation of motion. A ROM was developed by discretizing the equation of motion using straight beam mode shapes as basis functions in a Galerkin expansion. The results show evidence of the superharmonic resonances of order-three and two in addition to primary resonance. The co-existence of multiple stable orbits observed around only one stable equilibrium and under excitation waveforms with RMS voltage less than the snap-back voltage. These branches are a branch of small orbits within a narrow potential well and two branches of medium-sized and large orbits within a wider potential well. The transition between them results in the characteristic of the double peaks appearing in the frequency-response curve. We also report a bubble structure along the medium-sized branch consists of a cascade of period-doubling bifurcations and a cascade of reverse period-doubling bifurcations. A chaotic attractor develops within that structure at larger excitation levels. It demonstrates evidence of chaos with a wide-based spectrum and an elevated noise-floor. Odd-periodic windows appear also within the attractor including period-three (P-3), period-five (P-5) and period-six (P-6) windows. The chaotic attractor terminates in a cascade of reverse period-doubling bifurcations of period-four (P-4) orbits and period-two (P-2) orbits.
Ayman Alneamy; Mahmoud Khater; M S Al-Ghamdi; Ahmed Abdel-Aziz; Gleen Heppler; Eihab M Abdel-Rahman. Large oscillation of electrostatically actuated curved beams. Journal of Micromechanics and Microengineering 2020, 30, 095005 .
AMA StyleAyman Alneamy, Mahmoud Khater, M S Al-Ghamdi, Ahmed Abdel-Aziz, Gleen Heppler, Eihab M Abdel-Rahman. Large oscillation of electrostatically actuated curved beams. Journal of Micromechanics and Microengineering. 2020; 30 (9):095005.
Chicago/Turabian StyleAyman Alneamy; Mahmoud Khater; M S Al-Ghamdi; Ahmed Abdel-Aziz; Gleen Heppler; Eihab M Abdel-Rahman. 2020. "Large oscillation of electrostatically actuated curved beams." Journal of Micromechanics and Microengineering 30, no. 9: 095005.
We identify a new instability in electrostatic actuators dubbed quasi-static pull-in. We report experimental evidence of the instability and study its characteristics in two types of micro actuators operating in ambient air. We found that the underlying mechanism is a fast-slow dynamic interaction between slowly-varying electrostatic excitation and fast resonator response that instigate large non-resonant oscillatory orbits and eventually disappears in a global Shilnikov bifurcation. Based on these findings, we formulate and present a new taxonomy of pull-in instabilities in electrostatic actuators.
M. S. Al-Ghamdi; M. E. Khater; E. M. Abdel-Rahman; E. G. Nepomuceno. Quasi-Static Pull-in: an Instability in Electrostatic Actuators. Scientific Reports 2020, 10, 1 -8.
AMA StyleM. S. Al-Ghamdi, M. E. Khater, E. M. Abdel-Rahman, E. G. Nepomuceno. Quasi-Static Pull-in: an Instability in Electrostatic Actuators. Scientific Reports. 2020; 10 (1):1-8.
Chicago/Turabian StyleM. S. Al-Ghamdi; M. E. Khater; E. M. Abdel-Rahman; E. G. Nepomuceno. 2020. "Quasi-Static Pull-in: an Instability in Electrostatic Actuators." Scientific Reports 10, no. 1: 1-8.
Cellular polypropylene (PP) has been recently used in energy harvesting applications. In this work, we investigate its viability and long-term stability under various operating conditions. Specifically, the effect of constant stress and stress cycling on output power and long-term stability of ferroelectret energy harvesters is analyzed. Our findings show that after 112 days constant stress significantly increases the piezoelectric charge constant d 33 and output power from 0.51 μW for a stress-free harvester to 2.71 μW. It also increases the harvester center frequency from 450 to 700 Hz and decreases its optimal resistance from 7 to 5.5 M Ω .
Muhammed Kayaharman; Taylan Das; Gregory Seviora; Resul Saritas; Eihab Abdel-Rahman; Mustafa Yavuz. Long-Term Stability of Ferroelectret Energy Harvesters. Materials 2019, 13, 42 .
AMA StyleMuhammed Kayaharman, Taylan Das, Gregory Seviora, Resul Saritas, Eihab Abdel-Rahman, Mustafa Yavuz. Long-Term Stability of Ferroelectret Energy Harvesters. Materials. 2019; 13 (1):42.
Chicago/Turabian StyleMuhammed Kayaharman; Taylan Das; Gregory Seviora; Resul Saritas; Eihab Abdel-Rahman; Mustafa Yavuz. 2019. "Long-Term Stability of Ferroelectret Energy Harvesters." Materials 13, no. 1: 42.
An energy harvester composed of a microcantilever beam with a tip mass and a fixed electrode covered with an electret layer is investigated when subject to an external harmonic base excitation. The tip mass and fixed electrode form a variable capacitor connected to a load resistance. A single-degree-of-freedom model, derived based on Newton’s and Kirshoff’s laws, shows that the tip mass displacement and charge in the variable capacitor are nonlinearly coupled. Analysis of the eigenvalue problem indicates the influence of the electret surface voltage and electrical load resistance on the harvester linear characteristics, namely the harvester coupled frequency and electromechanical damping. Then, the frequency–response curves are obtained numerically for a range of load resistance, electret voltage and base excitation amplitudes. A softening nonlinear effect is observed as a result of decreasing the load resistance and increasing the electret voltage. It is found that there is an optimal electret voltage with the highest harvested electrical power. Below this optimal value, the bandwidth is very small, whereas the bandwidth is large when the electret voltage is above this optimal value. In addition, it is noted that for a certain excitation frequency, the harvested power decreases or increases as a function of electrical load resistance when the coupled frequency is closer to short- or open-circuit frequency, respectively. However, when the coupled frequency is between the short-circuit and open-circuit frequencies, the harvested power has an optimal resistance with the highest power. Increasing the excitation amplitude to raise the harvested power could be accompanied with dynamic pull-in instability and/or softening behavior depending on the electrical load resistance and electret voltage. However, large softening behavior would prevent the pull-in instability, increase the level of the harvested power, and broaden the bandwidth. These observations give a deeper insight into the behavior of such energy harvesters and are of great importance to the designers of electrostatic energy harvesters.
Bashar Hammad; Hichem Abdelmoula; Eihab Abdel-Rahman; Abdessattar Abdelkefi. Nonlinear Analysis and Performance of Electret-Based Microcantilever Energy Harvesters. Energies 2019, 12, 4249 .
AMA StyleBashar Hammad, Hichem Abdelmoula, Eihab Abdel-Rahman, Abdessattar Abdelkefi. Nonlinear Analysis and Performance of Electret-Based Microcantilever Energy Harvesters. Energies. 2019; 12 (22):4249.
Chicago/Turabian StyleBashar Hammad; Hichem Abdelmoula; Eihab Abdel-Rahman; Abdessattar Abdelkefi. 2019. "Nonlinear Analysis and Performance of Electret-Based Microcantilever Energy Harvesters." Energies 12, no. 22: 4249.
A. Alneamy; M. Al-Ghamdi; S. Park; M. Khater; E. Abdel-Rahman; G. Heppler. Dimpled electrostatic MEMS actuators. Journal of Applied Physics 2019, 125, 024304 .
AMA StyleA. Alneamy, M. Al-Ghamdi, S. Park, M. Khater, E. Abdel-Rahman, G. Heppler. Dimpled electrostatic MEMS actuators. Journal of Applied Physics. 2019; 125 (2):024304.
Chicago/Turabian StyleA. Alneamy; M. Al-Ghamdi; S. Park; M. Khater; E. Abdel-Rahman; G. Heppler. 2019. "Dimpled electrostatic MEMS actuators." Journal of Applied Physics 125, no. 2: 024304.
A novel electrostatic MEMS gas sensor is demonstrated. It employs a dynamic-bifurcation detection technique. The sensor detects ethanol vapor in a binary mode, reporting ON-state (1) for concentrations above a preset threshold and OFF-state (0) for concentrations below the threshold. The sensing mechanism exploits the qualitative difference between the sensor state before and after the dynamic pull-in bifurcation. Experimental demonstration was carried out using a laser Doppler vibrometer to measure the sensor response before and after detection. The sensor was able to detect ethanol vapor concentrations as 100 ppb in dry nitrogen. A closed-form expression for the sensitivity of dynamic bifurcation sensors was derived. It captures the dependence of sensitivity on the sensor dimensions, material properties, and electrostatic field.
M S Al-Ghamdi; Mahmoud Khater; Katherine Stewart; Ayman Alneamy; Eihab M Abdel-Rahman; Alexander Penlidis. Dynamic bifurcation MEMS gas sensors. Journal of Micromechanics and Microengineering 2018, 29, 015005 .
AMA StyleM S Al-Ghamdi, Mahmoud Khater, Katherine Stewart, Ayman Alneamy, Eihab M Abdel-Rahman, Alexander Penlidis. Dynamic bifurcation MEMS gas sensors. Journal of Micromechanics and Microengineering. 2018; 29 (1):015005.
Chicago/Turabian StyleM S Al-Ghamdi; Mahmoud Khater; Katherine Stewart; Ayman Alneamy; Eihab M Abdel-Rahman; Alexander Penlidis. 2018. "Dynamic bifurcation MEMS gas sensors." Journal of Micromechanics and Microengineering 29, no. 1: 015005.
M. S. Al-Ghamdi; M. E. Khater; E. M. Abdel-Rahman. Switching intermittency. Applied Physics Letters 2018, 113, 153501 .
AMA StyleM. S. Al-Ghamdi, M. E. Khater, E. M. Abdel-Rahman. Switching intermittency. Applied Physics Letters. 2018; 113 (15):153501.
Chicago/Turabian StyleM. S. Al-Ghamdi; M. E. Khater; E. M. Abdel-Rahman. 2018. "Switching intermittency." Applied Physics Letters 113, no. 15: 153501.
S. Mwalusepo; E.S. Massawe; T. Johansson; E. Abdel-Rahman; M. Gathara; E. Njuguna; P.A. Calatayud; O.J. James; T. Landmann; B.P. Le Ru. Modelling the Distributions of Maize Stem Borers at Local Scale in East African Mountain Gradients Using Climatic and Edaphic Variables. African Entomology 2018, 26, 458 -470.
AMA StyleS. Mwalusepo, E.S. Massawe, T. Johansson, E. Abdel-Rahman, M. Gathara, E. Njuguna, P.A. Calatayud, O.J. James, T. Landmann, B.P. Le Ru. Modelling the Distributions of Maize Stem Borers at Local Scale in East African Mountain Gradients Using Climatic and Edaphic Variables. African Entomology. 2018; 26 (2):458-470.
Chicago/Turabian StyleS. Mwalusepo; E.S. Massawe; T. Johansson; E. Abdel-Rahman; M. Gathara; E. Njuguna; P.A. Calatayud; O.J. James; T. Landmann; B.P. Le Ru. 2018. "Modelling the Distributions of Maize Stem Borers at Local Scale in East African Mountain Gradients Using Climatic and Edaphic Variables." African Entomology 26, no. 2: 458-470.
This paper investigates the performance of cantilever-type micro-mirrors under electromagnetic, electrostatic and dual actuation. We developed and validated a two-DOFs model of the coupled bending-torsion motions of the mirror and used it in conjunction with experiments in air and in vacuum to compare all three actuation methods. We found that electromagnetic actuation is the most effective delivering a scanning range of ±3.63° out of a geometrically allowable range of ±4° at a current amplitude i=3mA and a magnetic field of B=30 mT. Electrostatic actuation, whether alone or in conjunction with electromagnetic actuation, limited the stable angular range to smaller values (as small as ±0.019°) due to the presence of spurious piston motions. This is an innate characteristic of micro-scale electrostatic actuation, electrostatic force and undesirable piston motion grow faster than electrostatic torque and the desired angular as voltage is increased and limit the stable angular range. Finally, we found that the dual actuation can be used to design two-DOFs mirrors where electromagnetic actuation drives angular motion for optical beam steering and electrostatic actuation drives piston motion to control the mirror focus.
A M Alneamy; M E Khater; M S Al-Ghamdi; S Park; G R Heppler; E M Abdel-Rahman. Dual actuation micro-mirrors. Journal of Micromechanics and Microengineering 2018, 28, 075014 .
AMA StyleA M Alneamy, M E Khater, M S Al-Ghamdi, S Park, G R Heppler, E M Abdel-Rahman. Dual actuation micro-mirrors. Journal of Micromechanics and Microengineering. 2018; 28 (7):075014.
Chicago/Turabian StyleA M Alneamy; M E Khater; M S Al-Ghamdi; S Park; G R Heppler; E M Abdel-Rahman. 2018. "Dual actuation micro-mirrors." Journal of Micromechanics and Microengineering 28, no. 7: 075014.