Yikes! Missed that. Thanks for catching that, Bill. Guess I'll have to fire off a letter to their press person and see if that does any good.
Ezra -------------- Original message ---------------------- From: "Bill Potts" <[EMAIL PROTECTED]> > Unfortunately, they spoil it slightly by referring to the micron, rather > than the micrometer (µm). > > Bill Potts > Roseville, CA > http://metric1.org [SI Navigator] > > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf > Of [EMAIL PROTECTED] > Sent: Thursday, September 27, 2007 12:43 > To: U.S. Metric Association > Subject: [USMA:39475] Good use of SI in press release > > Note in the following U of Illinois press release the use of "attojoules". > No attempt at conversion to anything else. > Bit by bit ... > > Ezra > > ============= > > CHAMPAIGN, Ill. As the sizes of sensor networks and mobile devices shrink > toward the microscale, and even nanoscale, there is a growing need for > suitable power sources. Because even the tiniest battery is too big to be > used in nanoscale devices, scientists are exploring nanosize systems that > can salvage energy from the environment. > > Now, researchers at the University of Illinois have shown that a single > nanowire can produce power by harvesting mechanical energy. Made of > piezoelectric material, the nanowire generates a voltage when mechanically > deformed. To measure the voltage produced by such a tiny wire, however, the > researchers first had to build an extremely sensitive and precise mechanical > testing stage. > > With the development of this precision testing apparatus, we successfully > demonstrated the first controlled measurement of voltage generation from an > individual nanowire, said Min-Feng Yu, a professor of mechanical science > and engineering, and a researcher at the universitys Beckman Institute. > The new testing apparatus makes possible other difficult, but important, > measurements, as well. > > Yu and graduate students Zhaoyu Wang, Jie Hu, Abhijit Suryavanshi and > Kyungsuk Yum describe the measurement, and the measurement device, in a > paper accepted for publication in the journal Nano Letters, and posted on > the journals Web site. > > The nanowire was synthesized in the form of a single crystal of barium > titanate, an oxide of barium and titanium used as a piezoelectric material > in microphones and transducers, and was approximately 280 nanometers in > diameter and 15 microns long. > > The precision tensile mechanical testing stage is a finger-size device > consisting of two coplanar platforms one movable and one stationary > separated by a 3-micron gap. The movable platform is driven by a single-axis > piezoelectric flexure stage with a displacement resolution better than 1 > nanometer. > > When the researchers piezoelectric nanowire was placed across the gap and > fastened to the two platforms, the movable platform induced mechanical > vibrations in the nanowire. The voltage generated by the nanowire was > recorded by high-sensitivity, charge-sensing electronics. > > The electrical energy produced by the nanowire for each vibrational cycle > was 0.3 attojoules (less than one quintillionth of a joule), Yu said. > Accurate measurements this small could not be made on nanowires before. > > While the researchers created mechanical deformations in the nanowire > through vibrations caused by external motion, other vibrations in the > environment, such as sound waves, should also induce deformations. The > researchers next step is to accurately measure the piezoelectric nanowires > response to those acoustic vibrations. > > In addition, because of the fine precision offered by the mechanical > testing stage, it should also be possible to quantitatively compare the > intrinsic properties of the nanowire to those of the bulk material, Yu > said. This will allow us to study the scale effect related to > electromechanical coupling in nanoscale systems. > > Funding was provided by the National Science Foundation. Part of the work > was carried out in the Universitys Center for Microanalysis of Materials, > which is partially supported by the U.S. Department of Energy. > >
