The University of Southampton
University of Southampton Institutional Repository

In-situ conductivity, temperature, and dissolved oxygen (CT-DO) sensor system for marine measurement

Huang, Xi (2011) In-situ conductivity, temperature, and dissolved oxygen (CT-DO) sensor system for marine measurement University of Southampton, Faculty of Physical and Applied Sciences, Doctoral Thesis , 204pp.

Record type: Thesis (Doctoral)

Abstract

This works describes the development of a miniature high accuracy, low power CT-DO sensor system for in-situ oceanographic measurements. The sensors were fabricated on glass wafers, using micro-fabrication techniques. Three chip designs were made. The sensors in designs 1 and 2 include a seven-electrode conductivity sensor set in a flow channel, a four-ring-electrode open conductivity sensor, a Platinum Resistance Thermometer (PRT) bridge temperature sensor, and a DO sensor based on a platinum electrode inset into five 25 ?m deep wells. A 16-bit impedance measurement circuit was made to support the CT sensor. This has a typical battery life of one month with 10 s sampling interval. The initial CT accuracies are ±0.01 mS/cm and ±0.003 oC respectively. The seven-electrode conductivity sensor with channel suffered from a durability problem, which was discovered on a mid-Atlantic deployment. This problem was solved with the four-ringelectrode open conductivity and PRT bridge temperature sensor. Dock deployments and 8-week test in a calibration lab showed that the monthly drift was 0.02 mS/cm for the conductivity sensor, and less than 0.01 oC for the temperature sensor.

The DO sensor was calibrated to have an initial accuracy of ±5 ?m. A simple analytical model is proposed to estimate the effect of fluid flow. Tests show that the measured flow effect leads to an error of 1% DO, compared with an estimate of 10%. The complete CT-DO sensor was tested during a 75 day Indian Ocean cruise. A novel method of bio-fouling mitigation was tested utilizing electro-chemical reactions on the electrodes of the conductivity and DO sensors, and first results are promising. The CT system was also modified to measure low-conductivity solutions. This system was deployed in Greenland and results showed that the CT sensor can also work in fresh water and harsh environments. Future plans are to integrate the electronics into an ASIC, and to include a miniature sensor chip (design 3), to make a package the size of a pen for fish tag applications.

PDF Xi_Thesis-final_clean.pdf - Other
Restricted to Repository staff only until 30 March 2018.
Download (23MB)

More information

Published date: November 2011
Organisations: University of Southampton, Nanoelectronics and Nanotechnology

Identifiers

Local EPrints ID: 336240
URI: http://eprints.soton.ac.uk/id/eprint/336240
PURE UUID: a100a5dd-0399-4f6b-9cb8-2efa83cd9b28
ORCID for Hywel Morgan: ORCID iD orcid.org/0000-0003-4850-5676

Catalogue record

Date deposited: 29 Jun 2012 11:13
Last modified: 18 Jul 2017 06:09

Export record

Contributors

Author: Xi Huang
Thesis advisor: Hywel Morgan ORCID iD

University divisions

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×