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Proceedings Paper

Real-time frequency-domain fiber optic sensor for intra-arterial blood oxygen measurements
Author(s): J. Ricardo Alcala; Ian L. Scott; Jennifer W. Parker; Beauford W. Atwater; Clement Yu; Russell Fischer; K. Bellingrath
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Paper Abstract

A real time frequency domain phosphorimeter capable of measuring precise and accurate excited state lifetimes for determining oxygen is described. This frequency domain instrument does not make use of cross correlation techniques traditionally used in frequency domain fluorometers. Instead, the electrical signal from the detector is filtered to contain only the first several harmonics. This filtered signal is then sampled and averaged over a few thousand cycles. The absolute phase and absolute modulation of each sampled harmonic of the excitation and of the luminescence is computed by employing fast Fourier transform algorithms. The phase delay and the modulation ratio is then calculated at each harmonic frequency. A least squares fit is performed in the frequency domain to obtain the lifetimes of discrete exponentials. Oxygen concentrations are computed from these lifetimes. Prototypes based on these techniques were built employing commercially available components. Results from measurements in saline solution and in the arterial blood of dogs show that oxygen concentrations can be determined reproducibly. The system drift is less than 1% in over 100 hours of continuous operation. The performance of fiber optic sensors was evaluated in dogs over a period of 10 hours. The sensors tracked changes in arterial oxygen tension over the course of the experiment without instabilities. The overall response of the system was about 90 seconds. The update time was 3 seconds.

Paper Details

Date Published: 18 May 1993
PDF: 11 pages
Proc. SPIE 1885, Advances in Fluorescence Sensing Technology, (18 May 1993); doi: 10.1117/12.144720
Show Author Affiliations
J. Ricardo Alcala, The BOC Group Technical Ctr. (United States)
Ian L. Scott, The BOC Group Technical Ctr. (United States)
Jennifer W. Parker, The BOC Group Technical Ctr. (United States)
Beauford W. Atwater, The BOC Group Technical Ctr. (United States)
Clement Yu, The BOC Group Technical Ctr. (United States)
Russell Fischer, The BOC Group Technical Ctr. (United States)
K. Bellingrath, The BOC Group Technical Ctr. (United States)

Published in SPIE Proceedings Vol. 1885:
Advances in Fluorescence Sensing Technology
Joseph R. Lakowicz; Richard B. Thompson, Editor(s)

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