Bottom Up Microsystem Construction Strategies Built Upon 3D Directed Self-Assembly of Metallic and Polymeric Nanostructures

Robert W. Cohn
2008 2008 17th Biennial University/Government/Industry Micro/Nano Symposium  
Recently our group has developed two distinct methods of directed self-assembly of extremely high aspect ratio nanostructures. In one method a periodic micromachined array of vertical pillars is hand-brushed with a liquid polymer or nanomaterial-polymer composite leading to the spontaneous formation of two-point suspended nanofibers air-bridges and trampoline-like membranes (S. A. Harfenist et al., Nano Lett. 2004, S. Pabba et al., ACS Nano 2007. In some cases fibers as small as 10 nm diameter
more » ... as 10 nm diameter and exceeding 100:1 aspect ratios have been made with these crude methods of application that are then driven to make precise structures through capillary force driven thinning and self-assembly. In a second method, surfaces patterned with thin films of silver, when dipped into gallium at it melting point, which is near room temperature, can spontaneously grow Ag 2 Ga nanowires of constant diameter on the order of 100 nm diameter and up to at least 70 µm in length (M. M. Yazdanpanah et al., J. Appl. Phys. 2005). The process is remarkable in that these freestanding needles can be grown individually at selected locations and with a desired orientation with respect to the surface. Additionally the needles are extremely flexible, tough and ruggedly attached to the surface (V. V. Dobrokhotov et al., Nanotechnol. 2008). These approaches enable the rapid, often one step addition, of true third-dimensional complexity to substrates, that after initial micromachining, are at best 2.5 dimensional.
doi:10.1109/ugim.2008.43 fatcat:dqlnqkzptvc4zgfij5taa5chta