Graduation Semester and Year

2019

Language

English

Document Type

Thesis

Degree Name

Master of Science in Electrical Engineering

Department

Electrical Engineering

First Advisor

Jung-Chih Chiao

Abstract

pH level of biofluid is crucial in understanding physiological health. Commercial glass electrode pH sensors are bulky and cannot provide real time data. In this study, a novel miniature pH sensor capable of continuous wireless communication was developed, which is a promising technology for providing point-of-care diagnosis. Iridium Oxide because of its wide pH sensing range and biocompatibility has attracted attention from biomedical and food industries; high sensitivity of Iridium Oxide based sensor is attributed to its high charge density. Flexible polyamide Kapton substrate (127 µm) is taken as base substrate and E-Beam method is employed to deposit adhesion and metal layers. Electrodeposition processes such as Electroplating and Sol-Gel methods are employed to deposit Iridium Oxide on the Gold (Au) film. Electroplated electrodes showed high sensitivity (Super Nernstian response) and shorter lifetime, where-as Sol-Gel electrodes showed good sensitivity (Nernstian response) with longer lifetime. Hysteresis study based on the adhesion layer showed that Chromium (Cr) based samples exhibited higher hysteresis over Copper (Cu) based samples. But a combination layer of Cu over Cr, layered under the Au film showed the best performance. This type of samples was studied to attain super Nernstian response with sensitivity of about 62mV/pH and low hysteresis among other electrode types. Further, device packaging with cost effective and method to display pH reading on digital screen using Arduino (a low power consumption tool) is also reported.

Keywords

IrOx, pH, Sol-gel, Cyclic voltammetry, Lamination

Disciplines

Electrical and Computer Engineering | Engineering

Comments

Degree granted by The University of Texas at Arlington

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