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Title:Transistor-based biosensing: expanding the functionality of field effect transistors
Author(s):Salm, Eric
Director of Research:Bashir, Rashid
Doctoral Committee Chair(s):Bashir, Rashid
Doctoral Committee Member(s):Alam, Muhammad A.; Cunningham, Brian T.; Liu, Gang Logan
Department / Program:Bioengineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Electrical biosensor
ion-sensitive field-effect transistor (ISFET)
Field Effect Transistor (FET)
reference field-effect transistor (REFET)
solid-state electrode
nucleic acid amplification
Loop-mediated isothermal amplification (LAMP)
Polymerase chain reaction (PCR)
single cell lysis
DNA denaturation
Abstract:Since the invention of Polymerase Chain Reaction (PCR)-based amplification of nucleic acids by Kary Mullis in 1983(1), researchers have spent significant efforts to improve the sensitivity and selectivity of PCR assay and have dramatically enhanced its application(2). PCR is now an integral tool of modern biotechnology processes and biological identification. Due to the growing demands for on-site, rapid diagnosis, attention has been paid in realizing portable, fast, and low cost PCR machines. Through expanding the uses of the field effect transistor platform to include a novel design of heating/cooling, ultra-localized cell lysis, and electrical detection of nucleic acid amplification using an on-chip electrode, this thesis aims to enable the next generation of portable biosensors for primary care and on-site diagnostics. Chapter 2 presents an overview of the current state-of-the-art of electrical biosensors. In keeping with the goal of complete, integrated systems, methods for both sample preparation and detection were evaluated. Electrical sample preparation methods provide a unique opportunity to utilize electrical fields for cell lysis, concentration, and sample flow without the need for additional moving parts or reagents. Electrical detection methods offer a means of reducing reagents by eliminating the need for optical labels. Together, electrical sample preparation and detection will aid the development of portable, low-cost integrated biosensors. Chapters 3 and 4 look at utilizing transistors as platform for sample preparation and manipulation through DNA denaturation and cell lysis. Through application of a 10MHz, AC field between the shorted source-drain and the back-gate of the chip, fringing electric fields located just above the transistor surface are generated. These fringing electric fields can be used for dielectric relaxation of water molecules to generate heat for DNA denaturation as discussed in chapter 3, or to generate a transmembrane potential across a cellular membrane for ultra-localized cell lysis as discussed in chapter 4. These methods expand the functionality of the transistor platform by extending their uses into the realm of sample manipulation. Since the development of ISFETs for biosensing applications, transistors have been used for detection of biological analytes. Chapter 5 extends this functionality to electrical detection of nucleic acid amplification with an on-chip quasi-reference electrode. This method eliminates the need for a bulky/difficult to fabricate reference electrode and enables parallel detection of a large array of individual nucleic acid amplification reaction volumes. This method promises to reduce cost of PCR assays by eliminating optical components as well as improve the portability of the equipment by localizing the detection element to a disposable chip. As discussed in the future outlook presented in chapter 6, the silicon CMOS compatible technologies introduced can be made portable, rapidly heat and cool reaction volumes, and remain inexpensive so the ultimate vision of an array of PCR reaction chambers, where the target sample can be interrogated against an array of primers, can be realized. This thesis has added three new functionalities to the transistor platform. 1) Rapid DNA denaturation 2) Localized single cell lysis and 3) Electrical detection of amplification by-products with an on-chip electrode.
Issue Date:2014-05-30
Rights Information:Copyright 2014 Eric Salm
Date Available in IDEALS:2014-05-30
Date Deposited:2014-05

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