PORTABLE ELECTROCHEMICAL SENSING PLATFORM: FROM HARDWARE TO SOFTWARE KARTHK GANGADHARA Presented to the Faculty of the Graduate School of The University of Texas at Arlington in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE IN COMPUTER SCIENCE THE UNIVERSITY OF TEXAS AT ARLINGTON MAY 2020 2 Copyright © by Karthik Gangadhara 2020 All Rights Reserved 3 Acknowledgements Firstly, I would like to thank my advisor Dr. Sungyong Jung for giving me this opportunity. I have learnt a lot of valuable things from him. When I joined his lab in December 2018, I had no idea of how to conduct research, he taught me various aspects of research by being extremely patient and motivated me from time to time. I will be indebted to him for the rest of my life. I would also like to thank my committee members Dr. Jean Gao, and Dr. Dajiang Zhu for their consent and time to serve on my thesis defense committee and evaluate my work. I take this opportunity to thank all current and previous members of my lab, ISCS – Special thanks to Ms. Hyusim Park, without your guidance, help and support this work would have been impossible. I would also like to thank Mr. Manu Chilukuri, Ms. Shanthala Lakshminarayana, Mr. Younghun Park, Ms. Pallavi Vinubhai Bharoliya and Ms. Ruthya Chikkaputte Gowda. I had a wonderful time working with you all and I will always cherish it. Finally, I would like to thank my parents and my sisters for being my constant source of motivation and for all the love and support. April 30, 2020 4 Abstract PORTABLE ELECTROCHEMICAL SENSING PLATFORM: FROM HARDWARE TO SOFTWARE Karthik Gangadhara, M.S The University of Texas at Arlington, 2020 Supervising Professor: Sungyong Jung Recent advances in the electrochemical biosensors is increasing the popularity of the point of care devices since the electrochemical sensor can provide low cost, portability, detectability, experimental simplicity, and capacity to provide real time monitoring. The point of care devices has been used in various biomedical applications such as blood glucose monitors, pregnancy tests, HIV tests, hemoglobin level tests etc. However, the existing portable devices are limited to a specific sensing mechanism due to the inability to include the various electrochemical sensing techniques into a compact formfactor. Thus, there is a need for miniaturized all-in-one electrochemical sensing platform for the point of care devices. In this research, we present a portable electrochemical sensing platform designed and implemented from hardware to software for the point-of-care device to accommodate widely used electrochemical sensing mechanism including amperometry, voltammetry. To control the systems interfacing with the smart-devices and computers as well as displaying the obtained data, an android application and a graphical user interface were developed in open-source 5 programming using commercial-off-shelf components which consists of a microcontroller unit with readout circuit, a multiplexer, and wired communication unit. The proposed electrochemical sensing platform accommodates electrochemical techniques such as linear sweep voltammetry, cyclic voltammetry, amperometry, anode strip voltammetry, chrono amperometry and square wave voltammetry. We performed experiments on proposed system. The Potentiostat dummy cell array tests was performed for the aqueous phase detection and test results showed the linear response, which is important in electrochemical sensing system. 6 Table of Contents Acknowledgements ............................................................................................................. 3 Abstract ............................................................................................................................... 4 List of Figures ...................................................................................................................... 9 List of Tables .......................................................................................................................11 Chapter 1 Introduction ..................................................................................................... 12 Chapter 2 Background....................................................................................................... 17 2.1 Electrochemistry ..................................................................................................... 17 2.2. Electrochemical Cell ............................................................................................... 18 2.2.1 Galvanic cell (Voltaic Cell) ................................................................................ 19 2.2.2 Electrolytic Cell ................................................................................................. 19 2.3. Electrochemical Sensors ........................................................................................ 24 2.3.1 Potentiometric sensors .................................................................................... 24 2.3.2 Conductometric sensors .................................................................................. 27 2.3.3 Voltammetric sensors ...................................................................................... 29 2.3.4 Electrochemical Impedance Spectroscopy (EIS) .............................................. 40 2.4. Measurement Instrumentation ............................................................................. 42 2.4.1 Potentiostat and Galvanostat .......................................................................... 42 2.4.2 Potentiostat/galvanostat operation ................................................................. 43 7 2.4.3 Measurement Software ................................................................................... 45 2.4.4 Applications of Potentiostat/Galvanostat ........................................................ 46 2.5 Existing Works : Portable Electrochemical sensing systems ................................... 47 2.5.1 The universal Wireless electrochemical detector (UWED): ............................. 47 2.5.2 Universal mobile electrochemical detector (UMED): ...................................... 48 2.5.3 Dstat: ................................................................................................................ 48 Chapter 3 Proposed System .............................................................................................. 51 3.1. Hardware Design and Implementation .................................................................. 52 3.2. Software Design and Implementation ................................................................... 56 3.2.1. Firmware Design ............................................................................................. 56 3.2.2. Graphical User Interface Design (GUI) ............................................................ 61 3.3. Test Setup and Result ............................................................................................. 67 3.3.1 Cyclic Voltammetry .......................................................................................... 69 3.3.2 Square wave Voltammetry ............................................................................... 71 3.3.3. Linear Sweep Voltammetry ............................................................................. 72 3.3. 4. Amperometry ................................................................................................. 74 3.3.5 Anode Stripping Voltammetry ......................................................................... 76 3.3.6. Chrono Amperometry ..................................................................................... 78 Chapter 4. Conclusion ...................................................................................................... 81 8 References ......................................................................................................................... 83 9 List of Figures Figure 2.1. Hydrofluoric acid Redox Reaction ................................................................... 18 Figure 2.2. Electrolytic cell ............................................................................................... 20 Figure 2.3. Electrolytic cell Redox Reaction. ..................................................................... 21 Figure 2.4. Simple schematic of two electrode configuration where EA is the applied voltage and C and W are the counter and working electrodes, respectively. .............................. 22 Figure 2.5. Simple schematic of three electrode configuration where EA is the applied voltage and C, W, and R are the working and counter and reference electrodes, respectively. .. 23 Figure 2.6 Simple schematic of two electrode configuration for potentiometry ............. 25 Figure 2.7 Cyclic voltammetry Input and output plot ....................................................... 31 Figure 2.8 Anode stripping voltammetry Input and output plot ...................................... 33 Figure 2.9 Linear Sweep voltammetry Input and output plot .......................................... 34 Figure 2.10 Square wave voltammetry Input and output plot ........................................ 35 Figure 2.11 Chrono Amperometry Input and output plot ................................................ 37 Figure 2.12 Amperometry Input and output plot with respect to time. .......................... 39 Figure 2.13. Experimental EIS system set up using three electrode mode....................... 41