51 research outputs found
Large-Scale Integration of Nanoelectromechanical Systems for Gas Sensing Applications
We have developed arrays of nanomechanical systems (NEMS) by large-scale integration, comprising thousands of individual nanoresonators with densities of up to 6 million NEMS per square centimeter. The individual NEMS devices are electrically coupled using a combined series-parallel configuration that is extremely robust with respect to lithographical defects and mechanical or electrostatic-discharge damage. Given the large number of connected nanoresonators, the arrays are able to handle extremely high input powers (>1 W per array, corresponding to <1 mW per nanoresonator) without excessive heating or deterioration of resonance response. We demonstrate the utility of integrated NEMS arrays as high-performance chemical vapor sensors, detecting a part-per-billion concentration of a chemical warfare simulant within only a 2 s exposure period
Quantum entanglement with acousto-optic modulators: 2-photon beatings and Bell experiments with moving beamsplitters
We present an experiment testing quantum correlations with frequency shifted
photons. We test Bell inequality with 2-photon interferometry where we replace
the beamsplitters by acousto-optic modulators, which are equivalent to moving
beamsplitters. We measure the 2-photon beatings induced by the frequency
shifts, and we propose a cryptographic scheme in relation. Finally, setting the
experiment in a relativistic configuration, we demonstrate that the quantum
correlations are not only independent of the distance but also of the time
ordering between the two single-photon measurements.Comment: 14 pages, 16 figure
Single-protein nanomechanical mass spectrometry in real time
Nanoelectromechanical systems (NEMS) resonators can detect mass with exceptional sensitivity. Previously, mass spectra from several hundred adsorption events were assembled in NEMS-based mass spectrometry using statistical analysis. Here, we report the first realization of single-molecule NEMS-based mass spectrometry in real time. As each molecule in the sample adsorbs on the resonator, its mass and position of adsorption are determined by continuously tracking two driven vibrational modes of the device. We demonstrate the potential of multimode NEMS-based mass spectrometry by analysing IgM antibody complexes in real time. NEMS-based mass spectrometry is a unique and promising new form of mass spectrometry: it can resolve neutral species, provide a resolving power that increases markedly for very large masses, and allow the acquisition of spectra, molecule-by-molecule, in real time
Frequency fluctuations in silicon nanoresonators
Frequency stability is key to performance of nanoresonators. This stability
is thought to reach a limit with the resonator's ability to resolve
thermally-induced vibrations. Although measurements and predictions of
resonator stability usually disregard fluctuations in the mechanical frequency
response, these fluctuations have recently attracted considerable theoretical
interest. However, their existence is very difficult to demonstrate
experimentally. Here, through a literature review, we show that all studies of
frequency stability report values several orders of magnitude larger than the
limit imposed by thermomechanical noise. We studied a monocrystalline silicon
nanoresonator at room temperature, and found a similar discrepancy. We propose
a new method to show this was due to the presence of frequency fluctuations, of
unexpected level. The fluctuations were not due to the instrumentation system,
or to any other of the known sources investigated. These results challenge our
current understanding of frequency fluctuations and call for a change in
practices
Novas tecnologias construtivas e acidentes na construção civil: o caso da introdução de um novo sistema de escoramento de formas de laje
Permanent thickness loss prediction on aged shoe using numerical simulation: a pilot study
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