- Award ID(s):
- 1608692
- NSF-PAR ID:
- 10061885
- Date Published:
- Journal Name:
- ASME International Design Engineering Technical Conferences
- Page Range / eLocation ID:
- DETC 2016-60171 (13 pages)
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
Fabrication and acoustic performance of a microelectromechanical systems (MEMS) microphone are presented. The microphone utilizes an unusual electrostatic sensing scheme that causes the sensing electrode to move away, or levitate from the biasing electrode as the bias voltage is applied. This approach differs from existing electrostatic sensors and completely avoids the usual collapse, or pull-in instability. In this study, our goal is to fabricate a MEMS microphone whose sensitivity could be improved simply by increasing the bias voltage, without suffering from pull-in instability. The microphone is tested in our anechoic chamber and a read-out circuit is used to obtain electrical signals in response to sound pressure at various bias voltages. Experimental results show that the sensitivity increases approximately linearly with bias voltage for bias voltages from 40 volts to 100 volts. The ability to design electrostatic sensors without concerns about pull-in failure can enable a wide-range of promising sensor designs.more » « less
-
In this paper a novel electrostatic MEMS combined shock sensor and normally-closed switch is presented. The switch uses combined attractive and repulsive forcing to toggle a cantilever beam to and from the pulled-in position. The attractive force is generated through a parallel plate electrode configuration and induces pull-in. The repulsive force is generated through electrostatic levitation from a third electrode and serves to pull the beam out of its pulled-in position. A triboelectric transducer converts impact energy to electrical energy to provide voltage for the third electrode, which temporarily opens the switch if enough impact energy is supplied. Triboelectricity addresses the high voltage requirement for electrostatic levitation. The multi-electrode sensor also addresses the low current output from the generator because it acts as an open circuit between the parallel plate and levitation electrodes. A theoretical model of the switch is derived to analyze stability and the dynamic response of the cantilever. Threshold voltages to pull-in and release the beam through repulsive forcing is calculated. Output voltage plots from a prototype generator under a single impact are applied to the sensor-switch model to demonstrate the working principle of the sensor-switch is feasible.more » « less
-
We introduce a capacitive MEMS filter that uses electrostatic levitation for actuation and sensing. The advantage of this electrode configuration is that it does not suffer from the pull-in instability and therefore tremendously high voltages can be applied to this system. A large sensing voltage will produce a large output signal, which boosts the signal to noise ratio. The filter outputs about a 110mV peak-to-peak signal when operated at 175V, and can be boosted to 175mV by increasing the voltage to 250V. Because pull-in is eliminated, voltages much higher than 250V can be applied. An outline of the filter design and operating principle is discussed. A model of the filter is derived and analyzed to show the mechanical response and approximate peak-to-peak signal output. This study shows the feasibility of a capacitive sensor that is based on electrostatic levitation, and outlines the advantages it has over traditional parallel-plate electrode configurations. This design is promising for signal signal processing applications where large strokes are important.more » « less
-
Quantum and thermal fluctuations are fundamental to a plethora of phenomena within quantum optics, including the Casimir effect that acts between closely separated surfaces typically found in microelectromechanical systems (MEMS) and nanoelectromechanical systems (NEMS) devices. Particularly promising for engineering and harnessing these forces are systems out of thermal equilibrium. Recently, semiconductors with external bias have been proposed to study the nonequilibrium Casimir force. Here, we explore systems involving moderately biased semiconductors that exhibit strong repulsive Casimir forces, and we determine the effects of bias voltage, semiconductor bandgap energy, and separation for experimentally accessible configurations. Modes emitted from the semiconductors exert a repulsive force on a near surface that overcomes the attractive equilibrium Casimir force contribution at submicron distances. For the geometry of two parallel planes, those modes undergo Fabry–Pérot interference resulting in an oscillatory force behavior as a function of separation. Utilizing the proximity-force approximation, we predict that the repulsive force exerted on a gold sphere is well within the accuracy of typical Casimir force experiments. Our work opens up new possibilities for controlling forces at the nanometer and micrometer scale with applications in sensing and actuation in nanotechnology.
-
Parametric resonances in a repulsive-force MEMS resonator are investigated. The repulsive force is generated through electrostatic fringe fields that arise from a specific electrode configuration. Because of the nature of the electrostatic force, parametric resonance occurs in this system and is predicted using Mathieu’s Equation. Governing equations of motion are solved using numerical shooting techniques and show both parametric and subharmonic resonance at twice the natural frequency. The primary instability tongue for parametric resonance is also mapped. This is of particular interest for MEMS sensors that require high signal-to-noise ratios due to the large oscillation amplitudes associated with parametric resonance.more » « less