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Proceedings Paper

Time-of-flight application for fluid flow measurement
Author(s): Brian Markey; Yizhong Yu; Tamas Ban; Gagan Johal
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Paper Abstract

Fluidic measurement is a critical part of clinical care and homeostasis maintenance. This paper reports feasibility study of measuring flow velocities over a wide dynamic range using a non-contact measurement technique, optical time-of-flight (OTOF), with the objective of developing a compact instrument that can be used to measure fluid flow for IV medication delivery. In this study, a 1480nm laser diode focused to a 20μm spot introduces a heat bolus into the fluid. This localized temperature increase results in a correlated change in refractive index, detected downstream by observing defocusing of the visible beam, focused to a 10μm spot in the center of the fluid path. The OTOF measurement provides the centerline velocity of the fluid flow. CFD modeling ensured that laminar flow was fully developed; prior to the OTOF measurement point, thus providing a simple, empirical relationship between OTOF and fluid velocity, and hence volumetric flow rate. Measurements have been performed over a wide range of flow velocity from 1 mm/s to 1 m/s with approximately ±5% measurement error for broad ranges of fluid properties such as viscosity (0.77-13.88 cp), density (0.98-1.17 g/cm3) and temperature (5-35 °C). The dynamic range of measured velocity/flow rates is a function of the distance between the heating and the detection laser beams.

Paper Details

Date Published: 20 February 2009
PDF: 10 pages
Proc. SPIE 7186, Optical Diagnostics and Sensing IX, 71860S (20 February 2009); doi: 10.1117/12.822772
Show Author Affiliations
Brian Markey, Hospira, Inc. (United States)
Yizhong Yu, Hospira, Inc. (United States)
Tamas Ban, Hospira, Inc. (United States)
Gagan Johal, Hospira, Inc. (United States)

Published in SPIE Proceedings Vol. 7186:
Optical Diagnostics and Sensing IX
Gerard L. Coté, Editor(s)

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