Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nanoparticles could aid biohazard detection, computer industry

12.12.2002


A micrograph image of gold nanoparticles form on germanium, an advanced semiconductor material. These tiny particles could create better connections between microchips and the much larger wires that lead to other computer components. (Graphic/Lon Porter)


Nanoparticles form gradually after a semiconductor is dipped into a solution of metal salt. The cycle progresses from a surface of bare germanium (at the 12 o’clock position) progressing clockwise to the same surface 500 minutes after immersion. The process occurs naturally, without the expensive equipment that is otherwise necessary to produce high-purity metals. (Graphic/Lon Porter)


Nanotechnology could make life easier for computer manufacturers and tougher for terrorists, reports a Purdue University research team.

A group led by Jillian Buriak has found a rapid and cost-effective method of forming tiny particles of high-purity metals on the surface of advanced semiconductor materials such as gallium arsenide. While the economic benefits alone of such a discovery would be good news to chip manufacturers, who face the problem of connecting increasingly tiny computer chips with macro-sized components, the group has taken their research a step further.

The scientists also have learned how to use these nanoparticles as a bridge to connect the chips with organic molecules. Biosensors based on this development could lead to advances in the war on terrorism.



"We have found a way to connect the interior of a computer with the biological world," said Buriak, associate professor of chemistry in Purdue’s School of Science. "It is possible that this discovery will enable chips similar to those found in computers to detect biohazards such as bacteria, nerve gas or other chemical agents."

The research, which appears in today’s (Wednesday, 12/11) issue of Nano Letters, sprang from the team’s desire to attach metals to semiconductors in precise locations.

Computer chips, commonly made of silicon, contain circuits that are far smaller than those made from metal wires. But for an impulse from a keyboard or mouse to reach the microchip, the electronic signal must pass from a large wire onto the chip’s surface. The delicate interface between the macro and micro world is often accomplished by a tiny connection made of gold, chosen frequently over alternatives such as copper or silver, because it does not corrode in air. Gold’s advantages have made it the first choice for designers, though until now such advantages have come at a steep economic price.

"Gold works great once you actually get it onto the chip," said Lon Porter, a chemistry graduate student in Buriak’s group. "But by traditional manufacturing methods you need to begin with expensive, very high-purity gold. With our method, however, you’d no longer need the high-quality gold you might find in coins in Fort Knox – you could use the low-purity gold waste swept up from the coin factory floor."

In their purest forms, precious metals such as gold and platinum are among the most coveted substances in the world. But these metals are more commonly found in nature as part of low-purity compounds like metal salts – which, despite their name, are not salts you would use to flavor food or make a snowy roadway safe for driving. The amount of precious metals in these salts is low to begin with; when the salts are dissolved in liquid at the concentration that Buriak’s group needs to form nanoparticles, a test tube full of the solution is worth only pennies. But despite the low market value of the chemical solutions themselves, the effect Buriak’s group has discovered may nonetheless prove to be a gold mine.

"All you need to do to form nanoparticles is dip the semiconductor into the solution and wait," Porter said. "Though you begin with a solution worth less than the change in your pocket, you still end up with a layer of gold nanoparticles on the silicon that has the same purity as gold bullion. Because the reaction sustains itself, manufacturers would not need any special training or equipment to use it. From both a manpower and a technical perspective, the process is a real money saver."

The particles grow larger with increased time in the solution and eventually cover the semiconductor base with a bumpy coating. The roughness of the coating gives the base a greater surface area than it had by itself, a realization which led to the team’s second breakthrough.

"It’s similar to the way your brain packs a lot of surface area into the limited space inside your skull by folding in on itself many times," Porter said. "But the advantage we found for computer chips is not that we can increase their ’thinking power,’ per se. Rather, the resulting rough surface gives us a lot of nooks and crannies in which to secure a second group of molecules atop the gold – organic molecules that react in the presence of other chemicals."

The upshot of this double-layering is that the organic molecules could be chosen for their ability to react to the presence of nerve gas or biological contaminants. If a dangerous chemical reacted with an organic molecule, the metal nanoparticles could convey a signal downward to the chip that a biohazard was present.

"When a chemical reaction takes place, a small but measurable electrical change takes place," Porter said. "As metals are excellent conductors of electricity, nanoparticles could be the bridge that we need to make computers interface with the biological world."

Further refinement of their techniques has allowed the group to deposit nanoparticles of gold, platinum and other metals in specific areas of the semiconductor’s surface. Rather than a film that blankets the entire surface, the group can deposit the particles in a grid pattern or even draw lines with a microscopic "pen." These refinements could allow manufacturers to put their discoveries to use comparatively rapidly.

"We are not sure what application of our discoveries will appear first," Buriak said. "But there are many semiconductor companies out there that spend a lot of money on chip interfacing, and we expect they could all take advantage of this technique somehow."

This research was funded in part by the National Science Foundation.

Buriak’s group is affiliated with Purdue’s new Birck Nanotechnology Center, scheduled for completion in the fall of 2004. A dozen groups associated with the center are pursuing research topics such as microscopic machines, advanced materials and artificial organs.

Writer: Chad Boutin, (765) 494-2081, cboutin@purdue.edu

Sources: Jillian M. Buriak, (765) 494-5302, buriak@purdue.edu

Lon A. Porter Jr., (765) 496-3491, porterjr@purdue.edu

Purdue News Service: (765) 494-2096; purduenews@purdue.edu



Electroless Nanoparticle Film Deposition Compatible with Photolithography, Microcontact Printing, and Dip-Pen Nanolithography Patterning Technologies

By Lon A. Porter, Jr., Hee Cheul Choi, J. M. Schmeltzer, Alexander E. Ribbe, Lindsay C. C. Elliott,
and Jillian M. Buriak*

Nanoparticles of Au, Pd and Pt form spontaneously as thin, morphologically complex metallic films upon various semiconducting or metal substrates such as Ge(100), Cu, Zn, and Sn, via galvanic displacement from aqueous metal salt solutions. Patterning of these high surface area metal films into ordered structures utilizing photolithography, microcontact printing (-CP), and dip-pen nanolithography (DPN) is demonstrated on flat Ge(100), and (for -CP) on rough Zn foil.

Chad Boutin | Purdue News
Further information:
http://news.uns.purdue.edu/html4ever/021211.Buriak.nanoparticle.html
http://www.purdue.edu/
http://www.chem.purdue.edu/buriak

More articles from Materials Sciences:

nachricht Physics, photosynthesis and solar cells
01.12.2016 | University of California - Riverside

nachricht New process produces hydrogen at much lower temperature
01.12.2016 | Waseda University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>