Laser Printing of Multilayered Alternately Conducting and Insulating Microstructures

Production of multilayered microstructures composed of conducting and insulating materials is of great interest as they can be utilized as microelectronic components. Current proposed fabrication methods of these microstructures include top-down and bottom-up methods, each having their own set of drawbacks. Laser-based methods were shown to pattern various materials with micron/sub-micron resolution; however, multilayered structures demonstrating conducting/insulating/conducting properties were not yet realized. Here, we demonstrate laser printing of multilayered microstructures consisting of conducting platinum and insulating silicon oxide layers by a combination of thermally driven reactions with microbubble-assisted printing. PtCl2 dissolved in N-methyl-2-pyrrolidone (NMP) was used as a precursor to form conducting Pt layers, while tetraethyl orthosilicate dissolved in NMP formed insulating silicon oxide layers identified by Raman spectroscopy. We demonstrate control over the height of the insulating layer between ∼50 and 250 nm by varying the laser power and number of iterations. The resistivity of the silicon oxide layer at 0.5 V was 1.5 × 1011 ωm. Other materials that we studied were found to be porous and prone to cracking, rendering them irrelevant as insulators. Finally, we show how microfluidics can enhance multilayered laser microprinting by quickly switching between precursors. The concepts presented here could provide new opportunities for simple fabrication of multilayered microelectronic devices

Tunable nano devices fabricated by controlled deposition of gold nanoparticles via focused ion beam

Cataloged from PDF version of article.In this paper, we present the fabrication procedures as well as the preliminary experimental results of a novel method for significantly simplified deposition of charged nanoparticles at specific patterns based on focused ion beam (FIB) technology. The deposition method relies on the implantation of positive gallium ions on an insulated material which creates the basis for attracting the nanoparticles to the substrate. In order to substantiate the theory two patterns were generated on a silicon on insulator (SOI) chip with an upper layer of silicon of 200 nm. The two patterns are as follows: resolution target – consisting of six squares and 400 nm 400 nm circular sinusoidal tunnel. In addition, we demonstrate the utilization and applicability of the aforementioned method in a tunable radiation nano device as well as show its experimental characterization. © 2009 Elsevier B.V. All rights reserved

HU protein induces incoherent DNA persistence length

HU is a highly conserved protein that is believed to play an important role in the architecture and dynamic compaction of bacterial DNA. Its ability to control DNA bending is crucial for functions such as transcription and replication. The effects of HU on the DNA structure have been studied so far mainly by single molecule methods that require us to apply stretching forces on the DNA and therefore may perturb the DNA-protein interaction. To overcome this hurdle, we study the effect of HU on the DNA structure without applying external forces by using an improved tethered particle motion method. By combining the results with DNA curvature analysis from atomic force microscopy measurements we find that the DNA consists of two different curvature distributions and the measured persistence length is determined by their interplay. As a result, the effective persistence length adopts a bimodal property that depends primarily on the HU concentration. The results can be explained according to a recently suggested model that distinguishes single protein binding from cooperative protein binding. © 2011 by the Biophysical Society