Date of Award

Winter 2006

Document Type


Degree Name

Doctor of Philosophy (PhD)


Micro and Nanoscale Systems

First Advisor

Yi Su


A drying sessile drop moves the solute particles to the periphery where they get deposited in the form of a ring. This phenomenon is prevalent even with micro drops falling at high velocity from a piezo-actuator based inkjet printer. In polymer microelectronic field, this phenomenon is a major challenge for fabricating devices using inkjet printing. We exploited this problem and applied it for various novel applications in the field of polymer microelectronics.

Various dispensing techniques and temperature variations for micro-drop printing were used for modifying the micro-drops in such a way that the periphery of the micro-ring holds most of the solute as compared to inner base layer. Reactive ion etching (RIE) was used for removing the inner base layer in order to make the micro-rings completely hollow from the center. These micro-rings were applied in the fabrication of polymer light emitting diode, humidity sensor and vertical channel field effect transistor.

High resolution polymer light emitting diode array (>200 pixels/inch) was fabricated by inkjet printing of micro-ring and each micro-ring acts as a single pixel. These micro-rings were applied as a platform for layer-by-layer (LbL) nano-assembly of poly-3,4-ethylenedioxythiophene:poly-styrenesulfonate (PEDOT:PSS) for the fabrication of humidity sensor. Enhanced sensitivity of the humidity sensor was obtained when the inkjet printed micro-rings are combined with LbL assembled PEDOT:PSS films. During the fabrication of vertical channel field effect transistors, inkjet printed PEDOT:PSS micro-rings were used as source and the inner spacers between the adjacent micro-rings were used to make channel.

These micro-rings can also find other applications in the field of biological sciences. These micro-rings can be used as cell culture plates and as scaffolds for cell and/or tissue growth.