The Redesigning of a Pulse Oximeter

Jeffrey James

Sam Audia

University of PittsburghSenior Design - BioE1160

Ted Askar

Thomas Christophel

Background

What is a pulse oximeter?

• A simple non-invasive tool for monitoring the percentage of hemoglobin (Hb) which is saturated with oxygen.

Pulse OximeterProcessor/ Monitor

Background (cont)

How does an oximeter work?

• Light source originates from a LED at two wavelengths (650nm and 805nm).

• The light is partly absorbed by hemoglobin.

• A processor calculates the absorption at the two wavelengths and determines O2 concentration.

LED’s Receiver

Finger

Blood vessel

98%

Monitor

95%93%90%88%85%81%76%70%70%

Background (cont)

General Limitations

• The oximeter is dependant on pulsatile flow and would be unable to function when flow is sluggish (i.e. during vasoconstriction)

• Oximeters give no information about the level of CO2

• Accurate at oxygen saturations of 70 to 100% (+/-2%), but less accurate under 70%…. Under 70% is fatal.

et, al. Fearnley

Overview

Product• A pulse oximeter with replaceable adhesive.

• Alleviates problems involved with maintaining proper positioning of the device.

Intended solution• Design will be based upon current disposable pulse oximeters, but will incorporate a reusable sensor and replaceable adhesive.

Audience• Intended for patients using current pulse oximetry devices, specifically those who experience difficulties keeping the device positioned properly.

Project Goals

• Design cost effective pulse oximeter that maintains accuracy of current designs

• Design universal adapter to integrate replaceable device into current electronic monitoring systems

• High level timing goals• Research• Design• Prototyping

Existing design problems

• No universal connectors

• Disposable pulse oximeter • costly

• Clip/ Rubber slip• unstable attachment

• only for the finger

• Alarm• not discernable between situations

Design Alternatives

• Removable adhesive

• Universal connectors

• Different alarm sounds for different situations

Features & Benefits

• Replaceable Adhesive• Cost effective alternative to current disposable models

• Maintains ability of disposable adhesive models to stay in place

• Can be used on a variety of body parts • i.e. finger, toe, nose, forehead, or earlobe

• Increased versatility

• Universal Adapter• Can be integrated into electronics already in use

Adhesive

Professional Sketch

Pulse oximeter

Universal Connecter

Competitive Analysis

• Competitors • Nellcor

• Disposable pulse oximeters

• Costly due to nonreusability

• Nonin, Minolta, BCI• Finger tip pulse oximeter

• Portable

• Costly ($300+)

Competitive Analysis (cont.)

• Redesign Strengths • Inexpensive

• Reusable

• Multiple attachment sites (nose, ear, etc…)

• Weaknesses• Disposable adhesive (additional purchases)

Modeling Strategy

• Modeling and Analysis• Solidworks ANSYS

• LabView Pspice

Matlab

Team/Resources

• Four highly skilled undergrads

• Modeling and analysis software

• Electronic equipment (breadboard, voltmeter, oscilloscope, etc…)

• Locations/Support• St. Margaret’s Hospital (Mrs. Gartner)

• The University of Pittsburgh (BEH B69)

Schedule (Gantt Chart)

Task List

Jeffrey James Ted Askar Sam Audia Tom Christophel

TasksDesign/ Modeling

Circuitry/ Prototype Testing Research Virtual Testing

Conceptual Design Acquire partsCurrent Devices/ Components ANSYS

Modeling Device/ Adhesive Assembly Costs Lab View

Finished Model/ Rapid Prototype Pilot Testing Hazards Pspice

Group Members

Subtasks

Current Completions

• Design History File• Product Design Specification

• Objective Tree/ Functions-Means Analysis

• Initial Hazard Analysis

• Fault Tree Analysis

• FMEA

• Meeting with Mrs. Gartner

• Obtained 2 pulse oximeters

• Gantt Chart

Acknowledgements

Senior Design - BioE1160

Dr. Gartner

Mrs. Gartner

Funding: The University of Pittsburgh

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