[Show abstract][Hide abstract] ABSTRACT: The development of nanodevices that exploit the unique properties of nanoparticles will require high-speed methods for patterning surfaces with nanoparticles over large areas and with high resolution. Moreover, the technique will need to work with both conducting and non-conducting surfaces. Here we report an ion-induced parallel-focusing approach that satisfies all requirements. Charged monodisperse aerosol nanoparticles are deposited onto a surface patterned with a photoresist while ions of the same polarity are introduced into the deposition chamber in the presence of an applied electric field. The ions accumulate on the photoresist, modifying the applied field to produce nanoscopic electrostatic lenses that focus the nanoparticles onto the exposed parts of the surface. We have demonstrated that the technique could produce high-resolution patterns at high speed on both conducting (p-type silicon) and non-conducting (silica) surfaces. Moreover, the feature sizes in the nanoparticle patterns were significantly smaller than those in the original photoresist pattern.
[Show abstract][Hide abstract] ABSTRACT: The objective of this work is to propose a novel approach to prepare highly charged nanoaerosol particles. The nanoparticles are first enlarged by condensation of solvent vapor in a mixing-type particle magnifier (PM); the enlarged droplets are then charged by a corona ionizer; the charged droplets are finally dried to return the nuclei to their original size. Experiments were performed with neutralized nanoparticles generated by electrospray of colloidal suspensions, or by the evaporation–condensation method. Average particle charge obtained by this method was found to be approximately proportional to the Dp1.9.
[Show abstract][Hide abstract] ABSTRACT: Patterned deposition of nanoparticles is a prerequisite for the application of unique properties of nanoparticles in future nanodevices. Recent development of nanoxerography requires highly charged aerosol nanoparticles to avoid noise deposition due to random Brownian motion. However, it has been known that it is difficult to charge aerosol nanoparticles with more than two elementary charges. The goal of this work is to develop a simple technique for obtaining highly charged monodisperse aerosol nanoparticles by means of electrospray of colloidal suspension. Highly charged aerosol nanoparticles were produced by electrospraying (ES) and drying colloidal suspensions of monodisperse gold nanoparticles. Size and charge distributions of the resultant particles were measured. We demonstrate that this method successfully charges monodisperse nanoparticles very highly, e.g., 122 elementary charges for 25.0 nm, 23.5 for 10.5 nm, and 4.6 for 4.2 nm. The method described here constitutes a convenient, reliable, and continuous tool for preparing highly charged aerosol nanoparticles from suspensions of nanoparticles produced by either wet chemistry or gas-phase methods.
Journal of Colloid and Interface Science 08/2005; 287(1):135-40. DOI:10.1016/j.jcis.2005.01.078 · 3.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Patterned deposition of nanoparticles is prerequisite for the application of unique property of nanoparticles on future electronic devices. This study describes nanoparticle pattern deposition by means of particle mobility control and charge pattern transfer technique. Singly charged monodisperse nanoparticles were generated in gas phase by a series of aerosol generation, electric mobility classification and transport processes, and then, they were deposited on the substrates patterned with charges through a flexible polydimethyl siloxane (PDMS) stamp. The PDMS stamps were metal-coated by a sputter to reduce buckles on the surface of the stamps. Nanoparticle patterns were successfully achieved with the resolution of 500 nm and they were nearly consistent with those of the stamps.