A5022453992- Mechanical and Optical Resonators
- Advanced MEMS and NEMS Technologies
- Force Microscopy Techniques and Applications
- Acoustic Wave Resonator Technologies
- Photonic and Optical Devices
- Electrostatic Discharge in Electronics
- 3D IC and TSV technologies
- Integrated Circuits and Semiconductor Failure Analysis
- Seaweed-derived Bioactive Compounds
- Marine and coastal plant biology
- Fluid dynamics and aerodynamics studies
- Gyrotron and Vacuum Electronics Research
- Child and Adolescent Health
- Plant responses to water stress
- Insect Pest Control Strategies
- Irrigation Practices and Water Management
- Freezing and Crystallization Processes
- Electromagnetic Compatibility and Noise Suppression
- Law, logistics, and international trade
- Quantum Information and Cryptography
- Rangeland and Wildlife Management
- Insect behavior and control techniques
- Open Source Software Innovations
- Soil, Finite Element Methods
- Environmental Conservation and Management
University of Illinois Urbana-Champaign
2021-2024
Michigan State University
2022
Stanford University
2015-2022
Florida Institute of Technology
2022
University of California, Riverside
2008
Motorola (United States)
2002
University of Cape Town
1983
Quality factor (Q) is an important property of micro- and nano-electromechanical (MEM/NEM) resonators that underlie timing references, frequency sources, atomic force microscopes, gyroscopes, mass sensors. Various methods have been utilized to tune the effective quality MEM/NEM resonators, including external proportional feedback control, optical pumping, mechanical thermal-piezoresistive parametric pumping. This work reviews these mechanisms compares Q tuning using a position-proportional...
Parametric resonators have wide utility as bits, sensors, and frequency references. Controlling the phase states of a parametric resonator enables signal generation computation, but so far states' rich dynamics in presence nonlinearities received little attention. The authors delineate regimes for which control is possible, use this to experimentally operate on now-accessible solutions response. In context micro- nanoelectromechanical resonators, work can foster numerous applications pumping...
Subsurface water retention technology (SWRT) is a new, long‐term approach developed to improve storage capacities of sandy soils for sustainable crop production. It consists subsurface polyethylene membranes installed within the soil profile that prevent loss irrigation via deep percolation. Our objective was identify membrane shape and placement maximize reduction in losses. A greenhouse experiment conducted measure distribution surface‐irrigated sand lysimeter with six different geometry...
The thermomechanical motion imposes the fundamental noise limit in room-temperature resonant sensors and oscillators. Due to inherently low sensitivity of capacitive transduction microelectromechanical (MEM) resonators, its effects are often masked by subsequent amplifier measurement stages. In this work, we demonstrate a scheme for measuring kHz-MHz frequency MEM resonators across 1 μm gaps with 99.8% thermomechanical-noise-limited resolution. We delineate transimpedance gain our custom...
We derive the displacement noise spectrum of a parametrically pumped resonator below onset for self-excited oscillations. extend fluctuation-dissipation response thermomechanical-noise-driven to case degenerate parametric pumping as function pump magnitude and frequency while properly accounting quadrature-dependence thermal squeezing. use measurements with microelectromechanical cantilever corroborate our model.
Sensitive capacitive transduction of micromechanical resonators can contribute significant electrical dissipation, which degrades the quality factor eigenmodes. We theoretically and experimentally demonstrate a scheme for isolating damping mechanical resonator due to Ohmic dissipation in readout amplifier. The suppression arising from amplifier is strongly dependent on feedback resistance parasitic capacitance. By studying thermomechanical displacement noise spectrum doubly clamped beam, we...
Thermal-piezoresistive pumping is a thermoelectromechanical feedback mechanism used to tune micro- and nanomechanical resonators, simplifying signal amplification in resonant force sensors oscillators. The authors present generalizable model that predicts the effective quality-factor tuning due for micromechanical resonators of varying device geometry, orientation, material composition. They also find current models silicon's piezoresistivity diverge from experiment as doping increases....
Micromechanical oscillators provide periodic output signals for clocks and sensors by vibrating in a single mechanical mode. The mode is conventionally excited into self-sustained oscillations stabilized with an external electronic feedback loop. A paradigm emerging sustaining vibrations coupling the internal degrees of freedom, such as photons, electrons, or auxiliary modes. An open question these hybrid vibrational systems corresponding sources nonlinearity that can stabilize oscillations,...
Resonant sensors based on Micro- and Nano-Electro Mechanical Systems (M/NEMS) are ubiquitous in many sensing applications due to their outstanding performance capabilities, which directly proportional the quality factor (Q) of devices. We address here a recurrent question field: do dynamical techniques that modify effective Q (namely parametric pumping direct drive velocity feedback) affect said sensors? develop analytical models both cases, while remaining linear regime, introduce noise...
The Kerr Parametric Oscillator (KPO) is a nonlinear resonator system that often described as synthetic two-level system. In the presence of noise, switches between two states via fluctuating trajectory in phase space, instead following straight path. such trajectories makes it hard to establish precise count or even useful definition, “lifetime” state. Addressing this issue, we compare several rate counting methods allow estimate lifetime for levels. particular, peak Allan variance...
We use parametric suppression for signal amplifi-cation in a phase-modulated microelectromechanical (MEM) charge detector. Simultaneously driving and parametrically pumping MEM resonator with the appropriate relative phase increases slope near resonant frequency. this to increase sensitivity of electrometer more than tenfold.
In this work we present measurements of drive-induced negative nonlinear dissipation in doubly clamped microbeams fabricated a hermetically sealed package. We characterize the amplitude-frequency nonlinearity and system under direct drive. The nature is observed when measuring either directly- or parametrically-actuated response. By comparing to free ringdown response, confirm that induced by driving resonator. Drive-induced damping an important consideration for resonant sensors oscillators...
We measure the influence of ambient temperature (from -40 °C to 80 °C) on threshold current for self-oscillations in a thermal-piezoresistively pumped, capacitively sensed resonator. demonstrate that our flexural mode self oscillator, decreases with decreasing temperature. observe generation harmonics during self-oscillation amplitudes decrease and effective quality factors increase each successive mode. Following self-oscillations, we factor amplitude is extremely sensitive further DC increases.
We study thermal-piezoresistive cooling in silicon micromechanical resonators at large currents and high temperatures. Crossing a thermal transition region corresponds to steep reduction resonance frequency, an abrupt plateauing the effective quality factor, increase thermomechanical fluctuations. Comparing measurements with simulations suggests that second-order temperature coefficients of elasticity doped are not sufficient capture drop frequency currents. Overall, our results show there...
We study the influence of clamping loss, electrical damping, and transduction nonlinearity on measured nonlinear dissipation in encapsulated microme-chanical wheel resonators. Our measurements suggest that may arise from same phonon scattering origins as thermoelastic flexural mode resonators ranging size carbon nanotubes to guitar strings. These results point future investigations thermal bath engineering probe micro- nanomechanical
We demonstrate the first MEMS-only differential gyrator using a single Lamé mode electrostatic resonator. A is two-port device that produces pure non-reciprocal phase response and considered universal element from which isolators circulators can be derived. in this work gyration achieved any resonator, through very simple time-modulated biasing, without need for auxiliary spatio-temporal switching elements.
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Clamping loss in micromechanical resonators can strongly depend on the boundary conditions far away from actual vibrating structure because acoustic wavelength greatly exceeds device dimensions. We demonstrate a scheme for post-fabrication tuning of clamping flexural-mode and bulk-mode by modifying chip with frame. The measured quality factor increases more than an order-of-magnitude microcantilevers three when frame contact is minimized via suspension wirebonds. propose...
Encapsulated bulk mode microresonators in the megahertz range are used commercial timekeeping and sensing applications, but their performance is limited by current state of art readout methods. We demonstrate a using dispersive coupling between high-Q encapsulated micromechanical resonator lumped element microwave that implemented with commercially available components standard printed circuit board fabrication methods operates at room temperature pressure. A frequency domain measurement...
SUMMARY Samples of South African kelp seaweeds collected over a period 21 months were analysed for algin content (as percentage anhydrous mass) by colorimetric method. This method was an adaptation procedure described Blumenkrantz & Asboe-Hansen (1973), who used the colour reaction between meta-hydroxydiphenyl and furfurol to measure concentrations purified uronic acids in urine. While may fluctuate as much 50% within year, there little evidence suggest any marked seasonal variation either...
We observe significant temperature hysteresis in the resonant frequency and quality factor of silicon piezoresistive microcantilevers from room down to 40 K. The becomes increasingly pronounced as support beam length is reduced 100 μm 30 μm, leading over a twenty-fold difference Q values between sweep downwards upwards for device. Our work suggests that an important consideration thermal-piezoresistive oscillators other microelectromechanical resonators require multiple anchor points.