Cornell researchers have demonstrated a new way to make these resonators vibrate "in the plane" -- that is, side to side -- and have shown that this can serve a vital function: shaking off extraneous stuff that isn't supposed to be detected.
The research is reported in the July 14 online version of the journal Nano Letters and in the August print edition.
The typical resonator is a cantilever -- a narrow strip of silicon a few millionths of a meter long that can be made to vibrate up and down like a diving board just after someone jumps off. In research aimed at building the much-sought "lab on a chip," Professor Harold Craighead's group at Cornell and other researchers have shown that by binding antibodies to such resonators they can cause pathogens to attach to them. At the nanoscale, just adding the mass of one bacterium, virus or large molecule is enough to change the resonant frequency of vibration of the cantilever by a measurable amount, thereby signaling the presence of the pathogen.But "If, for example, you are trying to detect E. coli, there will be more things in the fluid than E. coli, and they can weakly absorb on the detector by electrostatic forces. This is a problem in any sort of biodetection," explained B. Rob Ilic, a researcher in the Cornell NanoScale Facility. The answer, he said, is to make the resonator vibrate from side to side. This will shake off loosely adhered materials, while whatever is tightly bound to an antibody will stay put.
Then the researchers demonstrated that in-plane motion can be created by hitting the base of the cantilever with a laser pulsed at the resonant frequency of the cantilever's in-plane vibration, which is different from the resonant frequency of its vibration perpendicular to the plane. To measure in-plane motion the researchers shined another laser on the free end of the cantilever and detected the chopping of the beam as the cantilever moved from side to side.
To show that in-plane motion could shake unwanted materials off of biosensors, the researchers distributed polystyrene spheres ranging from half a micron to a micron in diameter onto an array of cantilevers. The spheres, which attached themselves by electrostatic attraction, were removed by in-plane shaking. But when the cantilevers were made to vibrate more intensely up and down -- even so far that they bumped the "floor" below -- the spheres did not budge, nor did they during spinning of the entire chip.
In-plane vibration also could be used to determine how strongly particles are bound to the surface by observing how hard they need to be shaken to come loose, Ilic said. The ability to excite in-plane motion also has applications in making nanoscale gyroscopes, in nano optics and for basic physics experiments, he added.
Co-authors with Ilic and Craighead, who is the Charles W. Lake Jr. Professor of Engineering and professor of applied and engineering physics at Cornell, are Slava Krylov, professor in the Department of Solid Mechanics, Materials and Systems at Tel Aviv University, and Marianna Kondratovich, an undergraduate researcher in Cornell's Department of Mechanical and Aerospace Engineering.
Press Relations Office | EurekAlert!
New method gives microscope a boost in resolution
10.12.2018 | Rudolf-Virchow-Zentrum für Experimentelle Biomedizin der Universität Würzburg
A new 'spin' on kagome lattices
10.12.2018 | Boston College
What if a sensor sensing a thing could be part of the thing itself? Rice University engineers believe they have a two-dimensional solution to do just that.
Rice engineers led by materials scientists Pulickel Ajayan and Jun Lou have developed a method to make atom-flat sensors that seamlessly integrate with devices...
Scientists at the University of Stuttgart and the Karlsruhe Institute of Technology (KIT) succeed in important further development on the way to quantum Computers.
Quantum computers one day should be able to solve certain computing problems much faster than a classical computer. One of the most promising approaches is...
New Project SNAPSTER: Novel luminescent materials by encapsulating phosphorescent metal clusters with organic liquid crystals
Nowadays energy conversion in lighting and optoelectronic devices requires the use of rare earth oxides.
Scientists have discovered the first synthetic material that becomes thicker - at the molecular level - as it is stretched.
Researchers led by Dr Devesh Mistry from the University of Leeds discovered a new non-porous material that has unique and inherent "auxetic" stretching...
Scientists from the Theory Department of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science (CFEL) in Hamburg have shown through theoretical calculations and computer simulations that the force between electrons and lattice distortions in an atomically thin two-dimensional superconductor can be controlled with virtual photons. This could aid the development of new superconductors for energy-saving devices and many other technical applications.
The vacuum is not empty. It may sound like magic to laypeople but it has occupied physicists since the birth of quantum mechanics.
10.12.2018 | Event News
06.12.2018 | Event News
03.12.2018 | Event News
10.12.2018 | Physics and Astronomy
10.12.2018 | Life Sciences
10.12.2018 | Information Technology