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Fabrication and Testing of a Micro-scalable pH Sensor for Implanted Biomedical Use

Hilliard, Elias Todd (2011) Fabrication and Testing of a Micro-scalable pH Sensor for Implanted Biomedical Use. Master's Thesis, University of Pittsburgh. (Unpublished)

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Biosensors have recently moved into the arena of implantable devices. This incredible capability,to continuously monitor physiological parameters in-situ, allows for earlier and fundamentallymore accurate measurements. As pH is one of the most important biological factors, implantabledevices to measure pH are of great interest. Unfortunately, current pH sensors exhibit signal driftand require regular recalibration. Since this is impractical for implanted devices, much work isneeded in order to extend the working life of the pH sensor. The present work implemented threetechniques for fabricating a pH sensor based on an iridium oxide sensing layer that are compatiblewith micro-fabrication techniques and implantable devices. They are the oxidation of pure iridium,reactive sputtering of iridium in an oxygen environment, and anodic electrodeposition of iridiumoxide. The response of the sensors based on these indicating layers to tests in buer solution revealeda high degree of linearity. Slopes of the response were in agreement with those found in theliterature. Life tests were performed to characterize the signal drift over 20 hours of continuoususe. The established processes for fabricating the pH sensors provide a vehicle for further investigationinto techniques for extending life, specifically, by using microfluidic devices. Preliminarytests were done to show that interruption of the electrochemical circuit slows signal drift. This canbe accomplished in microscale devices using a microfluidic switching mechanism proposed here.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Hilliard, Elias Toddeth6@pitt.eduETH6
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairClark, William Wwclark@engr.pitt.eduWCLARK
Committee CoChairCho, Sung Kwonskc@engr.pitt.eduSKCHO
Committee MemberYun, Minheeyunmh@engr.pitt.eduMIY16
Date: 30 June 2011
Date Type: Completion
Defense Date: 19 August 2009
Approval Date: 30 June 2011
Submission Date: 26 August 2009
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Mechanical Engineering
Degree: MSME - Master of Science in Mechanical Engineering
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: iridium oxide; signal drift; EWOD; microfluidics
Other ID:, etd-08262009-134900
Date Deposited: 10 Nov 2011 20:01
Last Modified: 15 Nov 2016 13:49


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