P14026: Performance Evaluation Fixture
/public/

Build, Test, Document

Table of Contents

This page of the website will document 14026's journey through MSD II.

Team Critique

At the beginning of MSD II, the team was directed to analyze what prevented it from being as productive as possible, resulting in this Self Critique.

The team did a second critique at the end of MSD II.

Team Demonstrations

Project Plans

Project Budget

Shared Visions

Team Status Reports:

Shared Visions:

Risk Assessment

Problem Tracking

Test Plans & Test Results

Leak Tests

Configuration 1

On February 21, 2014 the team performed a leak test on the connections around the Trachea Resistance subsystem.
The leak test was performed by putting a soap and water solution on the connections of the subsystem. If bubbles
appeared after being connected to the PEV in Manual Mode then a leak exsisted.

This video shows when a leak did occur.

The following videos show the different connection points being tested:

On March 6, 2014 the team performed this leak test again using dish soap rather than foam hand soap.

This video shows when a leak did occur.

The following videos show the different connection points that were tested:

Configuration 2

On March 6, 2014 the team performed a leak test on the Trechea Resistance subsystem, with a focus on the
orifice plate, o-rings, and flanges. The leak test was performed by putting the subassembly in a sink full of water.
The suassembly was connected to the MediResp IV in Manual Mode. If bubbles appeared when air was pushed through the system,
then there was a leak.

This video shows when a leak did occur.

The following video shows the test being performed:

Configuration 3

On April 15, 2014 the team performed a leak test on the final prototype assembly.

This video shows the set up for the test. The following videos show the test being performed.

Compliance Testing

On February 26, 2014 the team performed an initiatl test to see if we could change the compliance of the lung.
This was done by hooking a manometer to the lung and the PEV to see if there was a change in pressure when weight
was added on top of the lung. This test was performed with the PEV set to have a flow of 12 LPM and volume set to 250mL.

This video shows the pressure the manometer read was 11 units when there was no additional
weight on the lung.

This video shows the pressure the manometer read was 13 units when a book and wallet were placed
on top of the lung (see picture below).

public/LungComplianceWeight.jpg

On March 16, 2014 the team performed a second test to test our ability to change lung compliance.

public/LungCompliance2.jpg

On March 29, 2014 the team performed another compliance test. The document below shows our results.

Pressure Sensor Testing

The connection of the pressure sensor to the breakout board is shown in the picture below.

public/PSConnect.png

The team tested that the pressure sensor can register a change in pressure by blowing into the sensor. The video below,
shows the oscilloscope changing as the pressure senor reads different pressures.

The team's finished pressure sensor board is shown below.

public/PressureSensorLayout.jpg

The team encased the pressure sensor subsystem to protect the board. The finished result is shown below.

public/PressureSensorCase.jpg

The team tested the accuracy of the pressure sensors by connecting a manometer to them with the heat shrunk tubing. The set up is shown in the pictures below.

public/Manometer Setup.JPG

public/Tube Connection.JPG

During the test the sensors the team raised the open side of the manometer until the water level dropped 1cm, compressing the air between the water and the pressure sensor. This increased the pressure 0.01 psi each time. The team then recorded the voltage value read by LabView. The following excel documents show the results of the test.

Build

Construction of Airway/Trachea Resistance and Manometer

Necessity

Looking over the test plan, it becomes evident that, in order to make the tester a true piece of instrumentation,
we must give its base parts a thorough accuracy analysis.
Rather than:

The team has elected to:


Theoretical Basis

public/manometer.PNG

Manometers are very common devices used to measure pressure, and are very useful in measuring the pressure drop across an orifice plate. By connecting one end to the upstream flow and another to the downstream flow (with respect to the orifice plate) the pressure difference is defined as:

public/EqnManometer.PNG


Build

Stage 1

Using PVC, PVC cement, Brass tubing for pressure tapping connections, tygon tubing, and schedule 80 flanges the setup below was fabricated. This setup will be used to validate that the pressure drops are what they're required and expected to be for each discreet airway resistance value.

public/Stage1Setup1.jpg

The locations of the pressure taps were chosen as such in order to measure fully developed flow and not have our data skewed by the 'vena contracta' phenomenon. This assures that the pressure at the entrance to the "lungs" is accurately representative of the resistance (pressure drop) experienced through varying airways and tracheae.

The next steps will be to acquire an o-ring, bolts, washers, and cut the orifice plate(s), after which testing can occur.

Stage 2

public/Stage2Setup.JPG

1/4" bolts, 1/4-1 1/4" washers, wing nuts, and o-rings that fit perfectly into the stock grooves on the schedule 80 flanges were added to the setup. The flow meter has also been connected to the setup.

Upon the cutting of the orifice plate via water jet, airway resistance validation testing can begin.

PCB

Schematics

Finished Schematic from February 4, 2014

Actuation

PUGH Charts

Check Valve

Generant's ICV Series Check Valve will serve to permit flow in only one direction, protecting the flow meter, and keeping pressure adding to the lung instead of leaking elsewhere. It has a nominal cracking pressure of 0.15 psi. Considering that the PEV delivers between 0.14 and 1 psi, this will eliminate the bottom 1% of our testable range.

Linear Actuator

Firgelli's Miniature Linear Motion Series L16 is sold at a 35:1 gear ratio, allowing for a maximum speed of 32mm/s (~2in/s) when driving a load of less than 40N. It comes with two mounting brackets and an LAC (Linear Actuator Control) Board. The LAC board purportedly has a USB output, and the company advertises a basic LabView VI which is free for download.

Solenoid Valve

The team is considering the Nitra DVP-2B Series Solenoid Valve. It is fully operational within our pressure range and will fit inside of 3/8'' tubing. It is normally closed, allowing the team to control when air will be released from lungs. This purchase is pending proper physical connection to LabVIEW.

Build & Testing

The video below shows the syringe being moved by the linear actuator.

Syringe Sizing Validation

The syringe was chosen based on the average volume in an adult's gasp for breath (10mL). The MediResp IV claims that this amount of gasp should trigger a breath while the device is in assist mode. When the team tested this theory by pulling on the syringe to simulate a breath, the PEV did not trigger a breath. When a larger syringe (60mL) was used, a breath was triggered. At this time the team can not conclude if the tester or the PEV is wrong about how much volume a breath is.

Data Capture

The team has decided to use labview to capture data from the TSI flowmeter attached to our testing device. The Labview program will allow us to capture and then export data to Excel for further analysis. Ultimately the goal will be to use one Labview program to capture data and control the actuator and solenoid valve.

The first version is the sample VI given on the TSI website stripped down to the functionality needed for our project.

14026_Labview V1.0.0.zip

The next version incorporates the ability to export captured data to be analyzed by Excel. Small bugs still left to resolve include not always capturing the entire length of the data stream and error when stopping the program before turning Run to the Off position.

14026_Labview V1.2.0.zip


Home | Planning & Execution | Problem Definition | Systems Design | Detailed Design | Build, Test, Document | Project Review | Photo Gallery