Nanotechnology February 2012 2011 November February
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BRIEFINGS TM Nanotechnology FEBRUARY 2012 2011 NOVEMBER FEBRUARY www.ScientificAmerican.com Inside Inside Microengineering with Swirls 2 CSI: Nanoparticles 2 A Trap for Ions and Atoms 4 Cooling to the Quantum Ground State 5 Hydrodynamics of Writing 5 Diamonds for Better Qubits 6 TM BRIEFINGS | Nanotechnology 2 carry orbital angular moment NANOTECHNOLOGY and magnetic moment, which BRIEFINGS leads to unique interactions with Swirls move matter. Jo Verbeeck of the Uni- versity of Antwerp and col- oto h tiny objects P Scientific American Briefings: Nanotechnology leagues from Austria, the Neth- k toc S I consists of summaries of recent peer-reviewed / I articles from the scientific literature. It draws INDIVIDUAL CELLS can be ma- erlands and Canada have now k these summaries from the journals of Nature nipulated by tiny vortices gener- demonstrated an electron vortex miers z Publishing Group, including Nature, Nature kA ated in fluids, rather than by the beam with a diameter of less Chemistry, Nature Materials, Nature AM Nanotechnolgy and the Nature Reviews journals. potentially harmful lasers or than 1.2 Å. Ad Mariette DiChristina electric fields typically used. The Electron vortex beams were liva, semen and blood on various Senior Vice President and Editor-in-Chief, concept is the brainchild of Li first created by passing a plane objects at the crime scene. At Scientific American Zhang and his colleagues at the wave beam through a graphite present, methods and tests used Philip Yam Managing Editor, Online, Scientific American Swiss Federal Institute of Tech- film that spontaneously formed to analyze body fluids are de- nology in Zurich, who used the a spiral structure, and acted as a structive and have a low speci- John Rennie Contributing Editor, Scientific American vortices to control the movement phase plate. This was difficult to ficity. Now, Nunzianda Frascione Michael Mrak of microscopic objects. reproduce and gave limited con- and colleagues at King’s College Design Director, Scientific American trol over the resulting beam. Ver- London have shown that mag- Philip Campbell beeck and co-workers had im- netic nanoparticles conjugated Editor-in-Chief, Nature proved on this approach by cre- with specific antibodies can de- Steven Inchcoombe ating a vortex beam with a tect and identify blood and sa- Managing Director, Nature Publishing Group, oto and President, Scientific American h holographic mask inside a trans- liva in situ on different types of P k mission electron microscope. substrates. Mike Florek toc S I Executive Vice President, Scientific American / However, the effective beam di- The researchers functional- ANS Bruce Brandfon Ev k ameter was several micrometers. ized magnetic nanoparticles AR Vice President and Publisher, Scientific American M Verbeek and colleagues have with fluorescently labeled anti- Wendy Elman The team placed a tank of now reduced this beam diameter bodies that recognize specific Vice President, Digital Solutions, Scientific American water in a rotating magnetic to atomic dimensions by placing components of red blood cells, Michael Voss Vice President and Associate Publisher, Marketing field, which triggered nickel a holographic mask in the con- white blood cells or saliva. They and Business Development, Scientific American nanowires in the tank to rotate denser plane of a state-of-the-art applied the nanoparticles to Christian Dorbandt in turn, generating microvor- microscope with double aberra- human blood or saliva that had Managing Director, Consumer Marketing, tices. The vortices trapped poly- tion correction. At 1.2 Å, the been smeared onto a glass slide. Scientific American styrene microbeads in the water. beam size is comparable to the After 30 minutes the unbound Matt Hansen Senior Production Editor, Nature Publishing Group By controlling the movement of size of the 2p orbital in a ni- nanoparticles were removed by a Kerrissa Lynch the nanowires, the authors could trogen atom (see image; left and magnet and the bound conju- Web Production Editor, Scientific American tightly control the movement of right panels show the beam and gates were visualized under a HoW to CoNtaCt uS the beads. the 2p orbital respectively, drawn fluorescent microscope. The an- For subscription correspondence, including They also successfully manip- approximately to scale). The tiny tibodies showed good specificity change of e-mail addresses: U.S. and Canada: 800-333-1199 ulated Escherichia coli bacteria vortex beam may allow atomic- and had little cross reactivity Outside the North America: +1-515-248-7684 using a pair of microspheres in resolution mapping of magnetic with other body fluids. Further- Email: [email protected] Postal address: Scientific American Briefings, Box place of the nanowires. states. more, bloodstains that were 3187, Harlan, IA 51537 —Daniel Cressey, Nature —Michael Segal, treated with the nanoparticles Annual subscription (12 issues): $19.95 (USD) For editorial comments: Nature Nanotechnology could still be used for DNA pro- ■■ Nano Lett. 10.1021/nl2032487 (2011) Email: [email protected] filing, suggesting that this www.ScientificAmerican.com ■■ Appl. Phys. Lett. doi: 10.1063/1.3662012 method could potentially save (2011) ELECTRON BEAMS money as DNA profiling would Scientific American is a trademark of only be carried out on identified Scientific American, Inc., used with permission. An atom-sized MAGNETIC NANOPARTICLES sections of the samples. The method also worked on samples vortex At the crime on substrates such as ceramic, TM ELECTRON BEAMS are typically paper and dark fabrics, thereby plane waves. This means that the scene increasing the likelihood of un- beam phase is identical for all DNA PROFILING is widely used covering important evidence at points in a plane perpendicular by forensic investigators to iden- the crime scene. to the beam direction. The phase tify an offender from just a single —Ai Lin Chun, of an electron vortex beam, on cell. However, equally valuable is Nature Nanotechnology the other hand, describes a the ability to detect and identify spiral. As a result, vortex beams traces of body fluids such as sa- ■■ Analyst doi: 10.1039/c1an15200a (2011) SUBSCRIBE >> TM BRIEFINGS | Nanotechnology 3 NANOELECTROMEChANICAL SYSTEMS SENSORS LIQUId CRYSTALS Keeping the Photon counting Light-driven noise down color change ANY DEVICE that amplifies a THE DEVELOPMENT of choles- oto signal inevitably adds noise, and h teric liquid crystals that offer P quantum mechanics prevents this k dynamic color tuning of their toc S I added noise being reduced below / reflection across the visible ON THE COVER a certain value. It is possible to ap- onsson spectrum would be of great in- k J k Extremely small vortices of proach this quantum limit by terest for many applications in hENRI swirling fluid offer a new way using superconducting devices to imaging, display technology optical fiber. for microengineers and amplify electrical signals, but and electronics. Unfortunately, biomedical researchers to these devices are complex. Now DISTRIBUTED TEMPERATURE this task has so far required manipulate tiny objects such Francesco Massel and co-workers sensing can be useful for moni- the use of three distinct liquid as individual cells. See page 2. at Aalto University and the VTT toring structures such as build- crystal films, each serving the Technical Research Centre of Fin- ings and pipelines. Michael red, green or blue regions sepa- Credit: PLAINVIEW/ land have shown that nanome- Tanner and colleagues from Her- rately and being switched on or iStockphoto chanical resonators can amplify iot-Watt University in the UK off electronically. In contrast, microwave signals, and that it may and the National Institute of using light as a means of be possible to reach the quantum Standards and Technology tuning reflectivity is attractive limit with this approach. (NIST) in Colorado, USA, have because it offers remote, spa- now built a distributed fiber tial and temporal control. So Raman sensor that can simulta- far, however, reports of such neously measure absolute tem- light-driven color changes are oto h P k perature at over 100 1.2-cm- dynamic and continuous; that toc S I / spaced positions along a single- is, the material remains a par- mode optical fiber. Although ticular color only for as long as orres T distributed fiber sensors have the controlling light is incident arlos C been around for a while, the re- on it. Quan Li and co-workers UIS L searchers claim that previous re- at Kent State University in the The Finnish team starts by search focused on using multi- USA have now synthesized two using lithography and focused ion- mode fibers and avalanche pho- light-driven chiral molecular beam etching to define a mechan- todiodes, which limited switches with very high helical ical resonator and a microwave detection wavelengths to around twisting powers that quickly cavity in a 150-nm-thick layer of 800–900 nm. In contrast, this and reversibly modulate their aluminum on a silica surface. latest work uses pulses of 1,550 structural reflection from blue When a pump signal is fed into nm light and measures the to red, via green, when irradi- this system, energy is transferred single-photon level Raman back- ated with light of ultraviolet or from the cavity to the resonator if scattered signal using supercon- visible wavelengths. Such the pump frequency is higher than ducting nanowire single-photon wavelength-selective reflection the resonance frequency of the detectors. The researchers