Electric Field Enhancement by Laser Light Focused at Electrode Edges for Controlled Positioning of Carbon Nanotubes

Abstract

We demonstrated single-walled carbon nanotube aggregation at electrode edges by local electric field enhancement by a focused laser irradiation. It was revealed that the formation of nanobubbles and their induced fluid motion play an important role in carrying nanotubes to the electric field enhancement region around the laser irradiation spot from the laser power dependence of the aggregation on electrode edges. Furthermore, we found that metallic nanotubes preferentially aggregated near irradiation spots by the investigation of the laser irradiation time dependence of the aggregation. This technique is useful for manipulating and bridging nanotubes between electrodes for device applications.

Simultaneous Formation and Spatial Patterning of ZnO on ITO Surfaces by Local Laser-Induced Generation of Microbubbles in Aqueous Solutions of [Zn(NH3)4]2+

“…20 The laser-induced bubbles create Marangoni and capillary flows that accumulate the dispersed nanomaterial along the substrate−bubble−solution three-phase contact line through evaporative mass flux, 21−23 similar to that observed for colloidal crystal growth by convective assembling, 24 which results in spatial patterns of the nanomaterial. Likewise, the bottom-up method by laser-induced microbubbles has been further applied to fabricate surface patterns of, e.g., polyoxometalates 25,26 and carbon nanotubes 27 via the concentration/accumulation of material at the three-phase contact line, which is currently known as "bubble-pen lithography". 28 The Marangoni flow around the microbubbles produced by irradiation from IR lasers has also been studied in detail.…”

Self-Assembly of Mesoscopic Materials To Form Controlled and Continuous Patterns by Thermo-Optically Manipulated Laser Induced Microbubbles

“…Discrete (noncontinuous) patterns of cadmium selenide quantum dots have also been achieved using a similar technique, where a bubble grown in the quantum dot dispersion around a "hot spot" produced by a focused laser on the gold substrate led to the self-assembly of the quantum dots on the substrate due to Gibbs−Marangoni convection, 19 while single-walled carbon nanotubes have been deposited on electrode edges using a similar technique. 20 This raises several important questions: Can continuous patterns be formed by directed self-assembly of nanostructured or, in general, mesoscopic materials? Can the patterning be completely controlled, fast (less than a second, note that the time scales in ref 18 was in the order of tens of seconds), and not depend on a particular choice of surface (such as gold as used in refs 17 and 18)?…”

“…More recently, single crystals of glycine have been grown from solutiononce again using bubble-mediated nucleation, but on this occasion the bubble was created due to the formation of a “hot spot” or high temperature region produced by a laser beam focused on a gold surface that was part of the sample holder for the solution. Discrete (noncontinuous) patterns of cadmium selenide quantum dots have also been achieved using a similar technique, where a bubble grown in the quantum dot dispersion around a “hot spot” produced by a focused laser on the gold substrate led to the self-assembly of the quantum dots on the substrate due to Gibbs–Marangoni convection, while single-walled carbon nanotubes have been deposited on electrode edges using a similar technique . This raises several important questions: Can continuous patterns be formed by directed self-assembly of nanostructured or, in general, mesoscopic materials?…”