Graduate Thesis Or Dissertation
 

Investigating rotating microelectrodes for rapid in situ detection of oxygen

Public Deposited

Downloadable Content

Download PDF
https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/mg74qs474

Descriptions

Attribute NameValues
Creator
Abstract
  • Rotating disc electrodes (RDEs) exploit the induced flushing of a radially spun electrode to increase the overall rate of analyte flux to an electrode sensing surface and its resulting signal current (i). Here initial efforts to evaluate a rotating platinum (Pt) microelectrode for efficacy as a rapid in situ dissolved oxygen (DO) sensor when submerged in natural waters, particularly seawater, are reported. The sensor tested employs a polished Pt disc (r = 50 µm) working electrode fixed at the tip of a rotating shaft as part of a three electrode system that includes a large surface area Pt wire (r = 250 µm) as a counter electrode and a silver/silver chloride (Ag/AgCl) reference electrode. An applied voltage (E = -0.75V) set between the Pt working and the reference leads to the reduction of molecular O2 at the disc surface and flow of electrons from the counter to the working electrode. This resulting electrical current was verified to be linearly proportional to concentrations of dissolved oxygen from 30 – 330 µM in seawater (S = 34), with sensitivities of ~0.6 nA / µM at 1000 rpm, when the electrode was run in a chronoamperometric mode. A similar linear range was also found in filtered fresh water collected from rivers. Evidence from flume experiments revealed shorten response times (t90% ≤ 0.10 s) compared to the majority of commercially available sensors, the result of both the rotational flushing of the electrode surface and the use of a bare Pt surface with no membrane. Physically durable, and an order of magnitude faster in response than the majority of reported aqueous DO sensors (t90% > 1.0 s), further optimized RDE systems similar to those detailed here could be used to resolve DO at high frequencies (2 - 18 Hz) in either fixed-point Eulerian or fast water column profiling applications. This first reporting of a truly in situ watertight electrode rotator additionally demonstrates the practicality of translating other RDE techniques to in situ detection.
License
Resource Type
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Committee Member
Academic Affiliation
Rights Statement
Publisher
Peer Reviewed
Language
Embargo date range
  • 2019-07-27 to 2021-08-27

Relationships

Parents:

This work has no parents.

In Collection:

Items

Thumbnail Title Date Uploaded Visibility Actions
file details ChacePeterJ2019.pdf 2019-07-26 Public Download