Navigation Links
Scientists moving closer to 'artificial noses'

These days, chemical analysts are expected to track down even single molecules. To do this highly sensitive detective work, nano researchers have developed minute strings that resonate in characteristic fashion. If a molecule docks onto one of the strings, then it becomes heavier, and its oscillations become measurably slower. Until recently, however, such "nano-electromechanical systems", or NEMS, have been short of practical applications. Physicists at LMU Munich have now made a breakthrough in this field: They have constructed a system of nanostrings made of non-conducting material, where each string can be electrically excited separately. Thousands of these strings can be produced on a small chip. One of the devices that could be created with this system is a highly sensitive "artificial nose" that detects various molecules pollutants for example individually. These new NEMS could also be used in a multitude of other applications acting as tiny pulse generators in mobile phone clocks, for example.

Quick, certain and cheap detection of single molecules is a task that chemical analysts are now expected to perform. Luckily, there is a method they can employ for this, which uses nanotechnology: Specifically, they use "nano-electromechanical systems", or NEMS. These systems involve strings with diameters of the order of 100 nanometers a ten-thousandth of a millimeter or a 1/500 of a human hair which can be excited to resonate in a characteristic fashion. If these strings are coated with the right kind of chemicals, then molecules will dock onto them. More specifically: only one kind of molecule can dock onto each string. When a molecule docks onto a string, the string becomes heavier and its oscillation slows down a tiny bit. "By measuring the period of oscillation, we could therefore detect chemical substances with molecular precision," explains Quirin Unterreithmeier, first author of the study. "Ideally, you would have several thousand strings sitting on a chip the size of a fingernail, each one for highly specifically recognizing a single molecule so you could build an extremely sensitive 'artificial nose', for example."

Until recently, however, getting such systems to work has proven technically difficult; one problem being to produce and measure the oscillations. While the nanostrings can be made to oscillate by magnetomechanical, piezoelectric or electrothermal excitement, this only works if the nanostrings are made of metal, or are at least metal-coated, which in turn greatly dampens the oscillations, preventing sensitive measurement. That hardly allows the detection of a single molecule. It also makes it harder to distinguish the different signals from differently oscillating strings.

The newly developed method now avoids these difficulties. Quirin Unterreithmeier, Dr. Eva Weig and Professor Jrg Kotthaus of the Center for NanoScience (CeNS), the Faculty of Physics of LMU Munich and the cluster of excellence "Nanosystems Initiative Munich (NIM)" have constructed an NEMS in which the nanostrings are excited individually by dielectric interaction the same phenomenon that makes hair stand on end in winter. Following this physical principle, the nanostrings, which are made of electrically non-conducting silicon nitride, are excited to resonate when exposed to an oscillating inhomogeneous electric field, and their vibration then measured.

The alternating electric field required for this stimulation was produced between two gold electrodes right up close to the string. The oscillations were measured by two other electrodes. "We created this setup using etching techniques," reports Weig. "But this was easily done even repeated ten thousand times on a chip. The only thing to do now is to make sure the strings can be individually addressed by a suitable circuit." All in all, this ought to be a technically easy exercise but one that will allow a breakthrough in chemical analysis. Yet there are even more applications that can be seen beyond this "artificial nose". Among other things, the nanostrings could be employed as the pulse generators in mobile phone clocks, for example. These novel resonators could even be used as ultra-sharp electrical signal filters in metrological systems.


Contact: Luise Dirscherl
Ludwig-Maximilians-Universitt Mnchen

Related biology technology :

1. Scientists discover dancing algae
2. Scientists demonstrate laser with controlled polarization
3. HybridSPE(TM)-Precipitation Technology Wins 2009 Scientists Choice Award for Best New Separations Product in 2008
4. Collexis Connects Biomedical Researchers and Clinical Scientists with the Collexis Expert Platform for Translational Research
5. Scientists patent corrosion-resistant nano-coating for metals
6. SenesTech Scientists Attend International Workshop on Fertility in New Zealand
7. Scientists prove graphenes edge structure affects electronic properties
8. Obama Advisor Joins Connecticut and International Scientists at New Haven Stem Cell Symposium
9. Scientists publish complete genetic blueprint of key biofuels crop
10. 2010 Japan Prize to Honor Scientists and Researchers in Industrial Production/Production Technology and Biological Production/Environment Fields
11. BOXX Personal Supercomputer for Research Scientists Featured at SC08
Post Your Comments:
(Date:11/24/2015)... Nov. 24, 2015 Halozyme Therapeutics, Inc. (NASDAQ: HALO ... New York on Wednesday, December 2 at ... , president and CEO, will provide a corporate overview. ... at 1:00 p.m. ET/10:00 a.m. PT . ... will provide a corporate overview. --> th Annual ...
(Date:11/24/2015)... N.C. , Nov. 24, 2015  Clintrax Global, Inc., a ... North Carolina , today announced that the company has set ... represented a 391% quarter on quarter growth posted for Q3 of ... and Mexico , with the establishment ... in December 2015. --> United Kingdom ...
(Date:11/24/2015)... New York , November 24, 2015 ... to a recent market research report released by Transparency ... projected to expand at a CAGR of 17.5% during ... "Non-invasive Prenatal Testing Market - Global Industry Analysis, Size, ... estimates the global non-invasive prenatal testing market to reach ...
(Date:11/24/2015)... Switzerland (PRWEB) , ... November 24, 2015 , ... InSphero ... organotypic 3D cell culture models, has promoted Melanie Aregger to serve as Chief Operating ... Ms. Aregger served on the management team and was promoted to Head ...
Breaking Biology Technology:
(Date:10/29/2015)... 29, 2015  Connected health pioneer, Joseph C. ... of technology-enabled health and wellness, and the business opportunities ... The Internet of Healthy Things . Long ... even existed, Dr. Kvedar, vice president, Connected Health, Partners ... delivery, moving care from the hospital or doctor,s office ...
(Date:10/29/2015)... 2015 Today, LifeBEAM , a ... 2XU, a global leader in technical performance sports ... with advanced bio-sensing technology. The hat will allow ... key biometrics to improve overall training performance. As ... will bring together the most advanced technology, extensive ...
(Date:10/27/2015)... -- Munich, Germany , October ... automatically maps data from mobile eye tracking videos created ... that they can be quantitatively analyzed with SMI,s analysis ... , October 28-29, 2015. SMI,s Automated Semantic Gaze ... tracking videos created with SMI,s Eye Tracking Glasses ...
Breaking Biology News(10 mins):