Date of Award

2012

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Systems Engineering

First Advisor

Desai, Salil

Abstract

This research investigates the controlled evaporation of microdroplets to the nano scale regime for scalable micro/nano manufacturing. A customized direct write inkjet printing system was utilized to generate monodisperse microdroplets of different fluid types. Two novel approaches were employed to achieve the research objective. The first approach incorporated a convective heat source (i.e. resistive heated ring) to induce controlled heat flux for microdroplet evaporation after ejection from the inkjet system. The temperature of the heated ring was varied to observe reduction of the microdroplet via heat transfer to its lateral periphery. The second approach employed a radiative source (i.e. CO2 laser) which enabled the droplet to be completely encapsulated by the lasing beam for controlled evaporation. The significance of lasing power, lasing frequency, nozzle size, and fluid type were assessed by statistical hypothesis testing. Volumetric reduction analysis of the two approaches demonstrated that the radiative source exhibited higher reductions of microdroplets under equivalent experimental conditions as compared to the convective source. Direct write inkjet printing of carbon nanotube colloids was employed to fabricate functional electronic devices (i.e. flexible thin film transistors) towards large scale manufacturing. Based on the findings of the droplet reduction experiments, two fluids namely, nanotube colloid and dye-saturated aqueous solution were evaluated for spread behavior at different lasing power outputs. Significant reductions in droplet volumes and spread behavior were observed over the power modulation range demonstrating scalable features with high repeatability. This research provides a framework for achieving controlled evaporation of features at the micrometer range with the aim of transforming those features to the nanoscale.

Download

Share

COinS