Date of Award

12-2020

Degree Name

Doctor of Philosophy

Department

Electrical and Computer Engineering

First Advisor

Dr. Massood Z. Atashbar

Second Advisor

Dr. Bradley J. Bazuin

Third Advisor

Dr. Paul D. Fleming

Fourth Advisor

Dr. Sherine O. Obare

Keywords

Additive printing processes, ruthenium complex and manganese oxide, inkjet printing, chronic wound healing, oxygen sensing and delivery, copper sensor

Abstract

In recent years, considerable research has been vested into the development of printed electronics (PE) to explore the best ways of fabricating electronic devices on flexible platforms using additive print manufacturing processes. PE produces flexible devices that are compatible with complex geometries, foldable applications and conformal to curved surfaces, with a promising potential for large‐area device fabrication at relatively lower manufacturing costs. This dissertation focuses majorly on the design and fabrication of novel flexible functional materials and devices for biomedical and environmental applications using additive printing processes.

Initially, a simple paper-based low cost and rapid prototypable platform with oxygen sensors and generators was developed for the first-time using additive printing process. The oxygen sensing patch was fabricated by depositing ruthenium based oxygen sensitive ink and manganese oxide (MnO2) based oxygenation ink on a parchment paper substrate using inkjet printing process. Parchment paper, which is biocompatible and non-toxic, was chosen as a substrate since it provides flexibility, fluid resistance and structural stability while simultaneously offering printability and gas permeability. The capability of the oxygen sensitive patch was investigated by measuring the fluorescence quenching lifetime of the printed dye for monitoring varying oxygen concentration levels. A fluorescent life time decay from ≈4 µs to ≈1.9 µs was obtained for the printed oxygen sensor patches for oxygen concentrations varying from ≈5 mg/L to ≈25 mg/L. The oxygen generation was achieved by flowing hydrogen peroxide (H2O2) over inkjet printed MnO2 catalyst on the parchment paper. The H2O2 was delivered/guided to the printed catalyst regions through a network of low-profile and flexible microfluidic channels that were bonded to the parchment paper and the flow was controlled by a programmable syringe pump. The results demonstrated oxygenation of 13% over 1 hour and in this platform, the oxygen-generation rates are tunable (by varying the H2O2 concentration or quantity of MnO2 deposited) and comparable to levels which affect wound healing. The integration of the fabricated oxygen sensors and generators has led towards the development of a low-cost multi-functional paper based flexible smart bandage for treating chronic wounds. This smart bandage can perform continuous oxygen sensing and provide on-demand oxygen delivery in a wound region.

Finally, copper (Cu2+), a heavy metal, is a vital micronutrient required for performing the fundamental physiological functions in most of the living organisms and plants. However, exposure or consumption of high concentrations of Cu2+ ions results in extreme toxicity and causes anemia, stomach cramps, and Alzheimer's, kidney and heart damage. A novel hexaazatriphenylene derivative, HNQP was successfully synthesized to selectively detect Cu2+ ions over other metal ions in aqueous solutions. A flexible and planar electrochemical sensor was fabricated on a polyimide substrate using an additive screen-printing process. The HNQP was drop casted on the electrochemical sensor and its capability to selectively detect Cu2+ ions was investigated by performing differential pulse voltammetry. The sensor was able to selectively detect Cu2+ ions in the presence of other interfering metal ions with a LOD and LOQ of 142 nM and 430 nM, respectively, which is lower than the specified toxicity levels of Cu2+ ions in drinking water (20 – 30 µM) set by the U.S. environmental protection agency (EPA) and WHO.

Comments

Fifth Advisor: Dr. Binu B. Narakathu

Access Setting

Dissertation-Open Access

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