Avinash Mamidanna is an ADAPT PhD student in Mechanical Engineering focusing on printing high-quality materials using reactive inks. For example, Avinash can print silver lines using reactive inks with resistivities within 90% of bulk silver (1.8 µΩ-cm compared to 1.6 µΩ-cm for bulk silver) without any sintering steps. The electrical properties of these reactive inks are good enough that Avinash and his colleagues within the Hildreth Research Group can reduce the amount of silver required to metallize a photovoltaic cell by 90% while also eliminating the high-temperature sintering step currently required for screen-printed pastes.

Avinash’s dissertation will focus on understanding how reaction kinetics of silver reactive inks combine with the mass transport and heat transfer of evaporating reactive ink droplets to determine silver morphology and electrical properties. Preliminary research showed that processing parameters, such as substrate temperature and solvent properties, have a direct impact on the morphology of these printed metal films. Building on this research, Avinash and his co-workers have developed silver reactive inks with varying reaction mechanisms and kinetics and have conducted experimental studies to correlate reaction kinetics to morphology. To better understand how the mass transport (fluid flow and evaporation), heat transfer, and reaction kinetics couple to dictate morphology, he is developing a COMSOL Multiphysics model to map how chemical potential varies with processing parameters and time. These chemical potential maps will be used to estimate particle nucleation and growth rate maps within the evaporating droplets to test the hypothesis that areas with high chemical potential will have the highest film densities.  The overall goal of this study is to be able to predict printed morphologies for any given set of processing parameters.

Avinash also has expertise in drop-on-demand (e.g., inkjet) printing of multi-material device systems that integrate multiple reactive inks on a single platform. Some of his previous work includes 3D printing of microfluid mixers and stretchable electronics devices. He anticipates completing his PhD in Fall 2019. He has ten publications so far, including first-author manuscripts in peer-reviewed scientific journals, such as ACS Applied Materials & Interfaces, Microfluidics and Nanofluidics, and Journal of Materials Science.

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