Bulletin of the American Physical Society
2005 APS March Meeting
Monday–Friday, March 21–25, 2005; Los Angeles, CA
Session V44: MEMS/NEMS: Applications and Resonators |
Hide Abstracts |
Sponsoring Units: GIMS Chair: Danhong Huang, Air Force Research Lab Room: LACC 518 |
Thursday, March 24, 2005 11:15AM - 11:27AM |
V44.00001: A Microwave Atomic Point Contact Displacement Detector N. E. Flowers-Jacobs, D. R. Schmidt, K. W. Lehnert A fundamental goal of nanomechanics is position detection at the Heisenberg limit. Recent experiments have employed single-electron transistor based position readout [1,2]. In contrast we use an atomic point contact (APC) as a displacement detector. In our measurements we probe the conductance of an APC formed between a nanomechanical beam and a fixed metal point to measure the harmonic motion of the beam. We measure the APC conductance at microwave frequencies and achieve an electrical bandwidth which contains the 18 Mhz mechanical resonance. We anticipate that this technique will approach the quantum limit of position measurement. Future applications include sensitive force detection and the ability to squeeze the thermal and quantum noise of the mechanical oscillator.{\\} {\\} [1] R. G. Knobel, A. N. Cleland, {\it Nature} {\bf 424}, 291 (2003){\\} [2] M. D. LaHaye, O. Buu, B. Camarota, K. C. Schwab, {\it Science} {\bf 304}, 74 (2004) [Preview Abstract] |
Thursday, March 24, 2005 11:27AM - 11:39AM |
V44.00002: Adhesion properties of gecko setae Ginel Hill, Anne Peattie, Roxanne Daniels, Robert Full, Thomas Kenny Millions of keratin hairs on gecko feet, called setae, act as a spectacular dry adhesive. Each seta branches into hundreds of smaller fibers that terminate in spatula-shaped ends. Morphological differences between the setae from different gecko species are suspected to affect both single-seta and whole-animal adhesion properties. Single-seta adhesive force measurements made using a MEMS piezoresistive cantilever capable of two-axis measurements are presented. [Preview Abstract] |
Thursday, March 24, 2005 11:39AM - 11:51AM |
V44.00003: Thermal Noise-Limited Detection of Radio-Frequency Piezoresistive Nanoelectromechanical Systems Igor Bargatin, Edward Myers, Jessica Arlett, Ben Gudlewski, Michael Roukes We have developed a method of measuring RF-range resonance properties of nanoelectromechanical systems (NEMS) with integrated piezoresistive strain detectors by using the piezoresistor as a signal downmixer. The technique takes advantage of the high strain sensitivity of semiconductor-based piezoresistors, while overcoming the problem of RF signal attenuation due to a high source impedance. Our technique also greatly reduces the effect of the cross-talk between the detector and actuator circuits. Using this technique, we achieve thermomechanical noise detection of cantilever resonance modes up to 71 MHz at room temperature, demonstrating that piezoresistive detection is a viable high-sensitivity alternative to current methods of displacement detection in high-frequency NEMS. [Preview Abstract] |
Thursday, March 24, 2005 11:51AM - 12:03PM |
V44.00004: Efficient and sensitive capacitive detection of a radio frequency nanoelectromechanical device P.A. Truitt, J. Hertzberg, K.C. Schwab Nanomechanical resonators show promise for application in areas such as signal processing, force detection, and readout of quantum information devices. Unfortunately, the commonly used readout methods are complex to implement and often require extreme conditions: cryogenic temperatures or large magnetic fields. A simple and sensitive method for detecting the motion of a nanomechanical resonator is desired. We present such a method, demonstrating sensitive capacitive detection of a 10 MHz nanomechanical resonator, which is voltage biased with respect to a nearby gate electrode. We use an LC resonator to impedance match the high impedance nanoelectromechanical device to 50 ohms. We will present our recent sensitivity measurements, and expect detection noise temperatures of Tn$\sim $40K using a standard preamplifier, and Tn$<$1K with a PHEMT cryogenic preamplifier. This technique appears viable over a wide range of resonator frequencies and device temperatures; we are currently implementing this technique for the readout of quantum coherent devices using a dispersive interaction. [Preview Abstract] |
Thursday, March 24, 2005 12:03PM - 12:15PM |
V44.00005: Solid Immersion Lens Microscopy Techniques for Enhanced Optical Displacement Detection in Nanoelectromechanical Systems D. Karabacak, T. Kouh, M.S. Unlu, B.B. Goldberg, Kamil Ekinci Nanoelectromechanical systems (NEMS) are drawing interest from both technical and scientific communities. These are electromechanical systems --- much like Microelectromechanical Systems (MEMS) --- mostly operated in their resonant modes, with dimensions in the deep submicron. Among the remaining technological challenges in NEMS operation is the detection of sub-nanometer displacements of these devices at high frequencies. Recently, optical interferometry techniques have been applied to displacement detection in NEMS operated at room temperature. However, the displacement sensitivity of such techniques degrades rapidly in the domain of NEMS where the diffraction limited optical spot size is much larger than the relevant device dimensions. Here, in an effort to remedy the aforementioned shortcomings, we integrate a solid immersion lens (SIL) to a sub-wavelength NEMS resonator, and demonstrate enhanced optical displacement sensitivity. The authors gratefully acknowledge support from the NSF under grants~No. 210752, 216274 and 324416. [Preview Abstract] |
Thursday, March 24, 2005 12:15PM - 12:27PM |
V44.00006: ZnO nanobelts for sensing NH4+ ions in aqueous buffer Kalpesh Upadhye, Scott Mao, Hai Lin An array of ZnO nanobelts is used for sensing changes in ammonium concentration and pH in aqueous environment. AC and DC measurements are performed to determine the conductive properties of the nanobelts. No significant changes in the DC resistance of the nanobelts are observed at different NH$_{4}^{+}$ concentrations between 3 {\&} 7 mM (pH $\sim $ 9.0-9.4). However, impedance spectroscopy (frequency: 0.1 to 100 kHz) measurements show that the frequency-dependent voltage-current phase angles shift with changing [NH$_{4}^{+}$] (between 1 {\&} 5 mM). The phase angle is constant at about 1.6 kHz with respect to different [NH$_{4}^{+}$] (pH). For frequencies $>$ 1.6 kHz, the voltage-current phase angle increases at higher concentrations of NH$_{4}^{+}$ (higher pH) and for frequencies $<$ 1.6 kHz, the phase angle decreases with increasing [NH$_{4}^{+}$]. These changes in the ZnO nanobelt conductive properties are attributed to modification of electronic states at the nanobelt surface due to interaction between the ionic species and the nanobelt. These results demonstrate that the phase angle can be used as a unique parameter for quantification of different ion concentrations and ZnO nanobelt arrays can be used for detection of ionic species in aqueous environment, which can be employed for \textit{in vitro} as well as \textit{in vivo} sensing of biomolecules. [Preview Abstract] |
Thursday, March 24, 2005 12:27PM - 12:39PM |
V44.00007: Effects of induced strain on GaAs nanomechanical resonator S.B. Shim, A. Gaidarzhy, S.W. Kang, S.W. Cho, P. Mohanty, Y.D. Park GaAs nanomechanical resonator structures, with patterned dimensions as small as 100 nm, were realized by e-beam lithography and by utilizing plasma-free wet etch chemistry processing techniques, to minimize any induced damages during fabrication, from latticed-matched low pressure MOCVD grown GaAs(500 nm)/InGaP(500 nm)/GaAs(001) heterostructures. The resulting doubly clamped GaAs suspended beams are characterized by magnetomotive techniques in cryogenic high vacuum conditions. An external strain is induced by applying a DC bias along with AC driving current in a constant magnetic field applied perpendicular to the length of the beam. We explore the B-squared dependence of the resonator response as affected by the induced strain as well as the position of the resonance peak in the frequency domain. We will also discuss the energy dissipation (1/Q) of the resulting beam structure due to induced strain as well as from induced damage and impurities in the GaAs layer. [Preview Abstract] |
Thursday, March 24, 2005 12:39PM - 12:51PM |
V44.00008: Observation of Quantized Displacement in Nanomechanical Oscillators Alexei Gaidarzhy, Guiti Zolfagharkhani, Robert Badzey, Pritiraj Mohanty We report the first observation of discrete response in gigahertz-frequency mechanical resonance modes of an antenna-like nanobeam oscillator. The hybrid design of the structure produces effective amplification of gigahertz frequency motion, which we detect magnetomotively with an RF network analyzer. High order ( $>$ 1.5 GHz) transverse modes of the structure cooled below 100 mK have thermal occupation numbers close to 1 ($N_{th} = k_BT / hf \sim 1$). The discrete nature of the observed response is possible evidence of transitions between the lowest energy levels of the macroscopic mechanical oscillator. This work is supported by the NSF (DMR, CCF, ECS), DOD (ARL), ACS (PRF), and the Sloan Foundation. [Preview Abstract] |
Thursday, March 24, 2005 12:51PM - 1:03PM |
V44.00009: Quantum nondemolition squeezing of a nanomechanical resonator Rusko Ruskov, Keith Schwab, Alexander Korotkov We discuss squeezing of the nanoresonator state produced by periodic measurement of position by a quantum point contact or a single-electron transistor. The mechanism of squeezing is the stroboscopic quantum nondemolition measurement generalized to the case of continuous measurement by a weakly coupled detector. The magnitude of squeezing is calculated for the harmonic and stroboscopic modulations of measurement, taking into account detector efficiency and nanoresonator quality factor. We also analyze the operation of the quantum feedback, which prevents fluctuations of the wavepacket center due to measurement back-action. Verification of the squeezed state can be performed in almost the same way as its preparation; similar procedure can also be used for the force detection with sensitivity beyond the standard quantum limit. [Preview Abstract] |
Thursday, March 24, 2005 1:03PM - 1:15PM |
V44.00010: Frequency and nonlinearity tuning in NEMS resonators Inna Kozinsky, H.W.Ch. Postma, M.L. Roukes Resonant devices based upon nanoelectromechanical systems (NEMS) are currently being developed for highly sensitive mass and force detection. The ability to tune the frequency of NEMS resonators in real time is indispensable for their use as sensors requiring both high precision and high frequency stability.~ We have explored a mechanism for tuning the resonant frequency of nanoscale silicon carbide resonators.~ We also demonstrate tuning of the nonlinearity in these devices and show how the linear operating regime can be restored at high (otherwise nonlinear) drive amplitudes and how dynamic range can be consequently increased.~ We present a theoretical model to explain these experimental observations, which also serves as a design guide for NEMS resonators with desired tunable properties. [Preview Abstract] |
Thursday, March 24, 2005 1:15PM - 1:27PM |
V44.00011: Operation of a Nanoelectromechanical Resonator Embedded in a Phase Locked Loop Circuit Taejoon Kouh, Kamil L. Ekinci Recently, a great deal of experimental and theoretical interest has been directed towards sub-micron resonant mechanical devices. These Nanoelectromechanical Systems (NEMS) are interesting for probing fundamental phenomena at the nanoscale and may serve in a number of important technological applications. One of the remaining engineering challenges in the domain of NEMS is the integration of NEMS resonators with feedback and frequency control systems. Here, we describe the operation of a NEMS resonator embedded in a phase locked loop circuit. The doubly-clamped beam NEMS resonators in this work are operated in their fundamental flexural modes --- their motion actuated electrostatically and transduced optically. Such schemes for phase locked operation of NEMS resonators offer opportunities in the development of NEMS based frequency control devices, and various mechanical and biological sensors. This project is supported by the NSF under grants No. 0216274 and 0324416. [Preview Abstract] |
Thursday, March 24, 2005 1:27PM - 1:39PM |
V44.00012: Feedback Cooling of an rf Nanomechanical Resonator Matthew LaHaye, Olivier Buu, Benedetta Camarota, Keith Schwab Ultra-sensitive force detection and direct observation of the quantum mechanical properties of nanomechanical resonators may require cooling of the resonators to temperatures which are virtually inaccessible by conventional, passive refrigeration techniques. We have recently demonstrated an alternative active cooling technique based upon the radio frequency single electron transistor (RFSET) displacement detector and optimal feedback. Preliminary data has shown that we are able to optimally damp the motion of a MHz-range nanoresonator by continuously monitoring its displacement with a RFSET, generating the appropriate feedback signal with a Kalman Filter controller, which then applies a force with a nearby electrode. With realistic improvements, it is believed that this technique can be used to cool nanoresonators to their ground-state as well as generate quantum squeezed-states. [Preview Abstract] |
Thursday, March 24, 2005 1:39PM - 1:51PM |
V44.00013: Efficient and Sensitive Readout of Nanomechanical Resonator Arrays Jared Hertzberg, Patrick Truitt, K. C. Schwab We have developed and demonstrated a simple and sensitive method to readout arrays of radio frequency nanomechanical resonators. The technique relies on an impedance-matching network to efficiently match a dc-voltage biased, capacitively coupled resonator to 50 ohms. We have fabricated and measured an array of 30, 10MHz resonators in this fashion, where groups of resonators may be selected for measurement by the application of the dc bias. The voltage applied to the gates also shifts the resonator frequency, revealing an interaction and frequency splitting between perpendicular, degenerate vibrational modes. This technique will find its utility in practical applications of nanomechanics as in ultra-sensitive mass or force detections, as well as in more fundamental studies involving quantum interaction and measurement with solid-state qubits. [Preview Abstract] |
|
V44.00014: Surface-tension-driven nanoelectromechanical relaxation oscillator B.C. Regan, S. Aloni, K. Jensen, A. Zettl We have developed a nanoelectromechanical relaxation oscillator with a surface-tension-driven power stroke. The oscillator consists of two liquid metal droplets exchanging mass, and its frequency is directly controlled with a low-level DC electrical voltage. Video of the device as observed by transmission electron microscope will be shown. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700