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Researchers directly deposit gold nanoparticles in suspension
August 10, 2007The delivery, manipulation and assembly of functional materials such as metal nanoparticles into predefined architectures and patterns is of great interest in nanotechnology. Nanoscale patterns of nanoparticles have the potential to be used in miniature electronic circuits or in plasmon waveguides to guide the transport of electromagnetic energy below the diffraction limit. Nanoparticles functionalized with biological materials can also be placed between electrodes for use in biosensing applications.
Researchers from Northwestern University have now demonstrated the ability of a third-generation nanofountain probe (NFP) to directly deposit gold nanoparticles, 15 nanometers in diameter, onto silicon substrates. The research is published online by the scientific journal Langmuir.
"Such a direct-write method of deposition provides better control over resultant patterns and simplifies the process of fabricating functional structures, as compared to conventional photolithographic or microstamping techniques," said Horacio D. Espinosa, professor of mechanical engineering in the Robert R. McCormick School of Engineering and Applied Science and co-author of the paper. Espinosa's group pioneered the development of the nanofountain probe.
The NFP is a cantilevered probe chip that can be mounted on commercial atomic force microscopy (AFM) equipment. On-chip reservoirs hold liquid inks such as nanoparticle solutions, which are delivered through enclosed channels to ring-shaped apertured tips. High throughput microfluidic transport of molecular inks to AFM tips is of great interest since fluid is a very effective medium for the direct delivery of molecules, which self-assemble on substrates with very specific nanoscale architectures.
"The ultimate goal of this project is to develop a robust microsystem platform for the mass production of nanoscale devices, sensors and structures using chemicals, biomolecules, nanoparticles, nanotubes and nanowires," said Espinosa.
Previous versions of the nanofountain probes were shown to be capable of depositing solutions of fluorescent dyes, alkanethiols and DNA. Among several design changes, the latest nanofountain probes have deeper microchannels to allow the facile delivery of larger particles such as gold nanoparticles 15 nanometers in diameter.
Probe-based deposition techniques are amenable to high-resolution, nanoscale and flexible patterns in which the desired structure can be easily altered at any time. Dip-pen nanolithography (DPN), in which a commercial AFM probe is coated with molecules to be deposited, is capable of making high-resolution patterns of many chemicals and biological materials. However, standard DPN techniques have not been able to deposit suspensions of solid nanoparticles.
"The nanofountain probe is not only capable of delivering such solutions but can do so continuously because the inks are contained in reservoirs on the chip," said Andrea Ho, a co-author and graduate student in Espinosa's group.
Because NFPs are batch-fabricated using standard micromachining processes, they can easily be mass-produced. The current NFPs produce nanoscale patterns with a linear array of 12 writing tips, but their design allows for straightforward scaling up to 2D arrays of tips. This would allow for the high-throughput, parallel deposition of nanoparticles with high resolution.
Northwestern University
The NFP is a cantilevered probe chip that can be mounted on commercial atomic force microscopy (AFM) equipment. On-chip reservoirs hold liquid inks such as nanoparticle solutions, which are delivered through enclosed channels to ring-shaped apertured tips. High throughput microfluidic transport of molecular inks to AFM tips is of great interest since fluid is a very effective medium for the direct delivery of molecules, which self-assemble on substrates with very specific nanoscale architectures.
"The ultimate goal of this project is to develop a robust microsystem platform for the mass production of nanoscale devices, sensors and structures using chemicals, biomolecules, nanoparticles, nanotubes and nanowires," said Espinosa.
Previous versions of the nanofountain probes were shown to be capable of depositing solutions of fluorescent dyes, alkanethiols and DNA. Among several design changes, the latest nanofountain probes have deeper microchannels to allow the facile delivery of larger particles such as gold nanoparticles 15 nanometers in diameter.
Probe-based deposition techniques are amenable to high-resolution, nanoscale and flexible patterns in which the desired structure can be easily altered at any time. Dip-pen nanolithography (DPN), in which a commercial AFM probe is coated with molecules to be deposited, is capable of making high-resolution patterns of many chemicals and biological materials. However, standard DPN techniques have not been able to deposit suspensions of solid nanoparticles.
"The nanofountain probe is not only capable of delivering such solutions but can do so continuously because the inks are contained in reservoirs on the chip," said Andrea Ho, a co-author and graduate student in Espinosa's group.
Because NFPs are batch-fabricated using standard micromachining processes, they can easily be mass-produced. The current NFPs produce nanoscale patterns with a linear array of 12 writing tips, but their design allows for straightforward scaling up to 2D arrays of tips. This would allow for the high-throughput, parallel deposition of nanoparticles with high resolution.
Northwestern University
Nanoparticles Current Events and Nanoparticles News RSSEngineers image nanostructure of a solid acid catalyst and boost its catalytic activity
The catalytic processes that facilitate the production of many chemicals and fuels could become much more environmentally friendly thanks to a breakthrough achieved by researchers from Lehigh and Rice Universities.
Findings show nanomedicine promising for treating spinal cord injuries
Researchers at Purdue University have discovered a new approach for repairing damaged nerve fibers in spinal cord injuries using nano-spheres that could be injected into the blood shortly after an accident.
Chemists describe solar energy progress and challenges, including the 'artificial leaf'
Scientists are making progress toward development of an "artificial leaf" that mimics a real leaf's chemical magic with photosynthesis - but instead converts sunlight and water into a liquid fuel such as methanol for cars and trucks.
Magnetic nanoparticles to simultaneously diagnose, monitor and treat
Whether it's magnetic nanoparticles (mNPs) giving an army of 'therapeutically armed' white blood cells direction to invade a deadly tumour's territory, or the use of mNPs to target specific nerve channels and induce nerve-led behaviour (such as the life-dependant thumping of our hearts), mNPs have come a long way in the past decade.
An exquisite container
In campy old movies, Lucretia Borgia swans around emptying powder from her ring into wine glasses carelessly left unattended. The poison ring is usually a confection of gold filigree holding a cabochon or faceted gemstone that can be broken to empty the ring's contents. It is invariably enormous - so large it is rather odd nobody seems to notice it.
Hard Rain: Pitt-led Researchers Create Nano-Particle Coating to Prevent Freezing Rain Buildup on Roads, Power Lines
Preventing the havoc wrought when freezing rain collects on roads, power lines, and aircrafts could be only a few nanometers away.
Knocking nanoparticles off the socks
Scientists in Switzerland are reporting results of one of the first studies on the release of silver nanoparticles from laundering those anti-odor, anti-bacterial socks now on the market.
Magnetic mixing creates quite a stir
Sandia researchers have developed a process that can mix tiny volumes of liquid, even in complicated spaces.
Nanowire biocompatibility in the brain: So far so good
The biological safety of nanotechnology, in other words, how the body reacts to nanoparticles, is a hot topic. Researchers at Lund University in Sweden have managed for the first time to carry out successful experiments involving the injection of so-called 'nanowires.'
Berkeley Researchers Find New Route to Nano Self-Assembly
If the promise of nanotechnology is to be fulfilled, nanoparticles will have to be able to make something of themselves. An important advance towards this goal has been achieved by researchers with the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) who have found a simple and yet powerfully robust way to induce nanoparticles to assemble themselves into complex arrays.
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