Oil monitoring with an optically stimulated contact potential difference sensor

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Please use this identifier to cite or link to this item: http://hdl.handle.net/1853/5021

Title: Oil monitoring with an optically stimulated contact potential difference sensor
Author: Ellis, Lisa Marie
Abstract: This thesis utilized the concept of an optically stimulated Contact Potential Difference (osCPD) sensor to monitor oil properties. The osCPD technique is a variant of the contact potential difference (CPD) method used to obtain surface properties of materials. The technique uses modulated light to stimulate electron charge carriers in silicon coated with a layer of oil. Demonstration of this oil monitoring design was done by placing different oil samples on the silicon surface and monitoring the corresponding electrical signal with the osCPD sensor. Experiments showed that the osCPD sensor produced an electrical signal that was related to the amount of time an oil sample was aged in an engine (or mileage). Further, a linear relationship was found between the relative conductivity of these oils and the osCPD signal. It is theorized that this osCPD signal is dependant on the charge transfer at the silicon and oil interface. Investigation of this interaction was carried out. Experiments showed that adding a silicon nitride passivation layer on the silicon surface eliminated the change in osCPD signal with oil properties. A model of this charge interaction was developed.
Type: Thesis
URI: http://hdl.handle.net/1853/5021
Date: 2004-07-07
Publisher: Georgia Institute of Technology
Subject: Contact potential difference
Oil monitoring
Department: Mechanical Engineering
Advisor: Committee Chair: Steven Danyluk; Committee Member: Jiri Janata; Committee Member: Shreyes Melkote
Degree: M.S.

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