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?• Non-invasive tool for monitoring the percent concentration of hemoglobin (Hb) saturated with oxygen.

Pulse OximeterProcessor/ Monitor

BackgroundHow does a pulse oximeter work?

Light to Frequency Converter

CPU Digital DisplayLED Driver

VR LEDIR LED

Photodiode

1. Source sends two wavelengths of light (red, 600-700nm, and infrared 850-1000nm) through an appendage

2. The Hb absorbs red light while O2Hb absorbs infrared light

3. Photodiode measures LED intensities

4. A processor calculates the absorbance ratio which is then used to determine oxygen saturation 1

2

3

4

Townsend et al.

Specific Aims

1. Develop a design and a prototype pulse oximeter sensor with disposable hypoallergenic adhesive(s) that can be shown to be more cost effective than current fully disposable models.

2. Test ability of prototype to adhere to surfaces under different conditions via volunteer based testing.

Existing design problems

• Current competitor disposable pulse oximeters

• are too costly

• Current competitor reusable pulse oximeters • have a clip or rubber slip which are very unstable

attachments

• require repair labor costs

• are very expensive

Overview

Product• A pulse oximeter with replaceable adhesive.

• Alleviate 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.

Adhesive

Design Sketch

Pulse oximeter

Features & Benefits

• Replaceable Adhesive• Cost effective alternative to current disposable

models

• Maintains ability of disposable adhesive models to stay in place

• Reusable sensor• Low cost replaceable sensor

SBIR Experimental Design

1. Prototype Development• develop reusable sensor design• develop hypoallergenic adhesive to be incorporated with reusable sensor• preliminary testing

2. Testing• Volunteers will test two models

• prototype • current disposable model

• The following dexterity tasks will be performed by both groups • eating• walking while attached to monitor• writing

• Different tasks will be performed in different conditions to evaluate effect of perspiration on adhesion

• wet• dry

• Analyze data to determine correlation between different factors • subsequent testing will be developed according to results

Modeling Strategy

• Modeling and Analysis• Solidworks ™

• Adhesive modeling• Reusable pulse oximeter modeling

• LabView ™• Create a virtual pulse oximeter processor

station

• Matlab ™ and MS Excel ™• Data analysis

Updated Task List

Audia James Askar ChristophelResearcher Modeler Manufacturer Prototype TesterResearch the potential hazards.

Conceptual design Circuit design of pulse oximeter

Pilot test the new adhesive with pulse oximeter

Research current pulse oximeters (competitors)

Model the adhesive with Solidworks

Purchase adhesives and pulse oximeters

Test new adhesive design verses current models.

Research possible size, type, and shape of adhesives.

Model the pulse oximeter with Solidworks

Assemble prototype device

Perform data analyses of the results

Specific aims (SBIR)

Relevant Experience (SBIR)

Significance (SBIR) Experimental Design and Methods (SBIR)

Semester Goals

1. Research• potential hazards• Sensor designs• Types of adhesives

2. Design• an inexpensive reusable sensor that maintains accuracy

of current competitors • a disposable adhesive that maintains proper positioning

on finger

3. Prototyping• Construct prototype• Preliminary testing versus current fully disposable models

Schedule (Gantt Chart)

Problems

• Research

• Circuit designs not public property

• Final model and virtual testing

• Parts needed

• Fixed budget

• Monitors/sensors expensive

Recent Successes

• Background research

• Conceptual model adopted

• SBIR rough draft• Experimental design protocol

• Some parts acquired

Thank you

Questions?