Mechanical stiffening, bistability, and bit operations in a microcantilever
TL;DR: In this paper, the authors investigated the nonlinear dynamics of microcantilevers and showed that at strong driving, the cantilever amplitude is bistable and suggested several applications for the bistability of the canticle.
Abstract: We investigate the nonlinear dynamics of microcantilevers. We demonstrate mechanical stiffening of the frequency response at large amplitudes, originating from the geometric nonlinearity. At strong driving the cantilever amplitude is bistable. We map the bistable regime as a function of drive frequency and amplitude, and suggest several applications for the bistable microcantilever, of which a mechanical memory is demonstrated.
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TL;DR: In this paper, the authors present a single micro electromechanical resonator with two outputs that enables the realization of multifunctional logic gates as well as other complex logic operations, such as OR, XOR, AND, NOR, and a half adder.
Abstract: Despite recent efforts toward true electromechanical resonator-based computing, achieving complex logics functions through cascading micro resonators has been deterred by challenges involved in their interconnections and the large required array of resonators. In this work we present a single micro electromechanical resonator with two outputs that enables the realization of multifunctional logic gates as well as other complex logic operations. As examples, we demonstrate the realization of the fundamental 2-bit logic gates of OR, XOR, AND, NOR, and a half adder. The device is based on a compound resonator consisting of a clamped-guided electrostatically actuated arch beam that is attached to another resonant beam from the side, which serves as an additional actuation electrode for the arch. The structure is also provided with an additional electrothermal tuning capability. The logic operations are based on the linear frequency modulations of the arch resonator and side microbeam. The device is compatible with CMOS fabrication process and works at room temperature.
17 citations
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...[11] Venstra WJ, Westra HJ, van der Zant HS....
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TL;DR: In this paper, the authors demonstrate logic and memory elements based on an in-plane clamped-clamped microbeam resonator, which is electrostatically actuated through a drive electrode and capacitively sensed at a sense electrode, while the resonance characteristics are modulated by dc voltage pulses provided at two separate partial electrodes, independent of the drive/sense electrodes.
Abstract: We demonstrate logic and memory elements based on an in-plane clamped–clamped microbeam resonator. The microresonator is electrostatically actuated through a drive electrode and the motional signal is capacitively sensed at a sense electrode, while the resonance characteristics are modulated by dc voltage pulses provided at two separate partial electrodes, independent of the drive/sense electrodes. For the logic applications, we use two separate electrodes to provide dc voltages defined as the logic inputs. The high (low) motional signal at on-resonance (off-resonance) state is defined as the logic output state “1” (“0”). For the memory operation, two stable vibrational states, high and low, within the hysteretic regime are defined as the memory states, “1” and “0,” respectively. We take advantage of the split electrode configuration to provide positive and negative dc voltage pulses selectively to set/reset the memory states (“1”/“0”) without affecting the driving and sensing terminals. Excluding the energy cost for supporting electronics, these devices consume energy in tens of picojoules per logic/memory operation. Furthermore, the devices are fabricated using silicon-on-insulator wafers, have the potential for on-chip integration, and operate at moderate pressure (~1 Torr) and room temperature.
14 citations
Cites background from "Mechanical stiffening, bistability,..."
...Note here that such hysteresis behavior on a nonlinear M/NEMS resonator has been thoroughly explored in the literature to construct memory-like elements [12], [16], [17], [20], [23], [24],...
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...amplitude modulation [17], [20], [23], magnetic field modulation [24], and electrothermal modulation [29]....
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TL;DR: It is demonstrated that the sign of the nonlinear coupling between orthogonal modes is dependent on the cross-section aspect ratio.
Abstract: We investigate the nonlinear mechanical properties of GaAs nanowires with anisotropic cross-section. Fundamental and second order flexural modes are studied using laser interferometry with good agreement found between experiment and theory describing the nonlinear response under mechanical excitation. In particular, we demonstrate that the sign of the nonlinear coupling between orthogonal modes is dependent on the cross-section aspect ratio. The findings are of interest for applications such as amplitude to frequency conversion and vectorial force sensing.
14 citations
TL;DR: In this paper, a theoretical framework is presented that demonstrates that the cantilever bending due to differential surface stress between opposite faces, a neglected effect in classical beam theory, plays a relevant role in the stiffness and eigenfrequencies of cantilevers.
Abstract: Ultrasensitive physical, chemical and biological sensors have emerged in the last decade based on the measurement of the eigenfrequencies of micro- and nanosized cantilever plates. Surface stress is omnipresent in these devices due to a variety of factors such as the fabrication process, temperature variations and analyte adsorption. How surface stress influences on the eigenfrequencies of cantilever plates has remained as an unsolved question in physics that has raised a long debate since first experiments in 1975. Recent theoretical models have shed light on the role of the net surface stress. Still, there exists a discrepancy between theory and some experimental reports, affecting to the capability for quantification of these sensors. In this Letter, we present a theoretical framework that demonstrates that the cantilever bending due to differential surface stress between opposite faces of the cantilever, a neglected effect in classical beam theory, plays a relevant role in the stiffness and eigenfrequencies of cantilevers. We develop a new theoretical framework that provides analytical equations that accurately describe the effect of surface stress on the first three vibration modes of cantilevers. Our findings provide the final piece of the puzzle for solving this long-standing problem in physics.
14 citations
TL;DR: In this paper, a mass-sensing platform based on the nonlinear dynamical response of a microcantilever embedded in a self-excitation feedback loop is proposed.
Abstract: A versatile mass-sensing platform based on the nonlinear dynamical response of a microcantilever embedded in a self-excitation feedback loop is proposed. It is experimentally shown that the delay imposed in the feedback loop by an adjustable phase-shifter can be used to finely tune this system to work in three different modalities, according to the desired mass sensing application: 1) as a continuous mass sensor, where the oscillation frequency smoothly responds to changes in the mass added to the resonator; 2) as a threshold sensor, where a sudden change in the oscillation frequency is triggered by an arbitrarily small change of mass added to the cantilever; and 3) as a stable microresonator, whose oscillation frequency is almost not affected by environmental conditions, such as changes in added mass, or in density/viscosity of the surrounding fluid. This variety of dynamical responses was registered for a wide range of added masses, in the form of beads individually attached to the cantilever. A complete analytical model to explain the observed experimental results is derived and shows a strong agreement with the measured data. The high resolution and signal-to-noise ratio, as well as the threshold and stable sensing modalities obtained with this closed-loop technique, are not available in the current open-loop microcantilever-based mass sensors.
13 citations
References
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IBM1
TL;DR: The long relaxation time of the measured signal suggests that the state of an individual spin can be monitored for extended periods of time, even while subjected to a complex set of manipulations that are part of the MRFM measurement protocol.
Abstract: Magnetic resonance imaging (MRI) is well known as a powerful technique for visualizing subsurface structures with three-dimensional spatial resolution. Pushing the resolution below 1 micro m remains a major challenge, however, owing to the sensitivity limitations of conventional inductive detection techniques. Currently, the smallest volume elements in an image must contain at least 10(12) nuclear spins for MRI-based microscopy, or 10(7) electron spins for electron spin resonance microscopy. Magnetic resonance force microscopy (MRFM) was proposed as a means to improve detection sensitivity to the single-spin level, and thus enable three-dimensional imaging of macromolecules (for example, proteins) with atomic resolution. MRFM has also been proposed as a qubit readout device for spin-based quantum computers. Here we report the detection of an individual electron spin by MRFM. A spatial resolution of 25 nm in one dimension was obtained for an unpaired spin in silicon dioxide. The measured signal is consistent with a model in which the spin is aligned parallel or anti-parallel to the effective field, with a rotating-frame relaxation time of 760 ms. The long relaxation time suggests that the state of an individual spin can be monitored for extended periods of time, even while subjected to a complex set of manipulations that are part of the MRFM measurement protocol.
1,379 citations
Journal Article•
TL;DR: In this article, the authors reported the detection of an individual electron spin by magnetic resonance force microscopy (MRFM) and achieved a spatial resolution of 25nm in one dimension for an unpaired spin in silicon dioxide.
Abstract: Magnetic resonance imaging (MRI) is well known as a powerful technique for visualizing subsurface structures with three-dimensional spatial resolution. Pushing the resolution below 1 µm remains a major challenge, however, owing to the sensitivity limitations of conventional inductive detection techniques. Currently, the smallest volume elements in an image must contain at least 1012 nuclear spins for MRI-based microscopy, or 107 electron spins for electron spin resonance microscopy. Magnetic resonance force microscopy (MRFM) was proposed as a means to improve detection sensitivity to the single-spin level, and thus enable three-dimensional imaging of macromolecules (for example, proteins) with atomic resolution. MRFM has also been proposed as a qubit readout device for spin-based quantum computers. Here we report the detection of an individual electron spin by MRFM. A spatial resolution of 25 nm in one dimension was obtained for an unpaired spin in silicon dioxide. The measured signal is consistent with a model in which the spin is aligned parallel or anti-parallel to the effective field, with a rotating-frame relaxation time of 760 ms. The long relaxation time suggests that the state of an individual spin can be monitored for extended periods of time, even while subjected to a complex set of manipulations that are part of the MRFM measurement protocol.
1,192 citations
01 Jan 1978
TL;DR: In this article, a set of mathematically consistent governing differential equations of motion describing the nonplanar, nonlinear dynamics of an inextensional beam is developed with the objective of retaining contributions due to nonlinear curvature as well as nonlinear inertia.
Abstract: This paper is divided into two parts. The authors’ purpose in Part I is to formulate a set of mathematically consistent governing differential equations of motion describing the nonplanar, nonlinear dynamics of an inextensional beam. The beam is assumed to undergo flexure about two principal axes and torsion. The equations are developed with the objective of retaining contributions due to nonlinear curvature as well as nonlinear inertia. A priori ordering assumptions are avoided as much as possible in the process. The equations are expanded to contain nonlinearities up to order three to facilitate comparison with analogous equations in the literature, and to render them amenable to the study of moderately large amplitude flexural-torsional oscillations by perturbation techniques. The utilization of the order-three equations in the analysis of nonlinear beam oscillations is the subject of Part II.
362 citations
TL;DR: In this paper, the atomic force microscope (AFM) tip and sample are adjusted by pH and electrolytes to distribute the force applied to the AFM tip over a large sample area.
354 citations
TL;DR: Pulsed microwave reflection measurements on nanofabricated Al junctions show that actual devices attain the performance predicted by theory, and the absence of on-chip dissipation is shown.
Abstract: We have constructed a new type of amplifier whose primary purpose is the readout of superconducting quantum bits. It is based on the transition of a rf-driven Josephson junction between two distinct oscillation states near a dynamical bifurcation point. The main advantages of this new amplifier are speed, high sensitivity, low backaction, and the absence of on-chip dissipation. Pulsed microwave reflection measurements on nanofabricated Al junctions show that actual devices attain the performance predicted by theory.
328 citations