Development of Directed-Assembly Based Printing Process for Electronics, Sensing, and Material Applicatio

A new high-rate directed assembly based nanomanufacturing process has been developed at the NSF Center for High-rate Nanomanufacturing to print electronics and sensors on flexible nano-enabled devices using reusable templates. These 'damascene templates' are designed to achieve not only a flat topographical surface consisting of conductive patterns and insulated areas but also multi-scale (macro/micro/nano) size conductive patterns having the same electric potential during electrophoretic assembly, thereby allowing uniform assembly and high yield transfer of nanomaterials. The governing parameters for this printing process, such as the surface energy of damascene templates, applied potential during electrophoretic assembly, temperature and pressure for transferring nanomaterials have been investigated. We have also demonstrated that Offset Printing using damascene templates is highly compatible with various nanomaterials such as carbon nanotubes (CNT), silica nanoparticles, and numerous polymers.;There are many challenges to making such a scalable template based nanoscale printing process. First, damascene templates must be large scale and have multi-scale (macro/micro/nano) conductive patterns on a perfectly flat surface. A flat surface is essential to obtaining high yield transfer, and a CMP (Chemical Mechanical Polishing) process is used to achieve it. Unfortunately, CMP processes are not suitable for large scale templates and multi scale conductive patterns because they are limited by wafer size and have inherent defects, 'dishing' and 'erosion', which happen when the template has different sized patterns with different materials. Developing new fabrication processes for damascene templates could overcome these problems by replacement of CMP with more suitable techniques.;A multi-layer transfer printing process for printing different devices using various nanomaterials has been developed. This is important for developing printed applications using Offset Printing such as flexible transistors, antennas, chemical and biological sensors, and metal circuit printing. This work enables high-rate manufacturing of nanomaterial devices in various fields such as a mobile product, flexible displays, biosensor, and energy harvesting.