Much smaller it is possible to
deposit the gold in suspension
“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 from Northwestern University.
The third-generation nanofountain probe (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. Standard dip-pen nanolithography (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, graduate student in Espinosa’s group.
COMPAMED.de; Source: Northwestern University