Joe Tartakoff
Customer/Graduate Consultant
jat2704@rit.edu
Matthew Myers
ISE Project Leader
mcm8294@rit.edu
Nick Dominesey
ME Lead Engineer
njd3574@rit.edu
Jason Inman
EE Team Member
jpi7658@g.rit.edu
Chris Smith
ME Team Member
cjs5192@g.rit.edu
Ellie Sanford
ME Team Member
egs5491@rit.edu
Michael Edson
EE Team Member
mce5689@rit.edu
Detailed Design Review
2/8/2013
Agenda
1.
2.
3.
4.
5.
6.
7.
8.
9.
Project Overview
Customer Needs and Engineering
Specifications
Chosen Concept
Block Diagram
Feasibility Analysis
Testing Plan
Work Breakdown Structure
System Design Proposal
Bill of Materials
MSD Project 13022: Breakaway VAD
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Detailed Design Review
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Project Background
6-10% of all people worldwide over the
age of 65 will develop heart failure.
 There are 287,000 deaths per year due
to heart failure in the US.
 The Thoratec Heartmate II Left
Ventricular Assist Device (LVAD) is a
bridge-to-transplant device that assists
the heart, pumping blood throughout the
body for those who are awaiting a heart
transplant.

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Present LVAD External Power
http://www.thoratec.com/
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Project Summary

The transcutaneous power cord that
connects the implanted device to the
external motor control unit is often a
source of infection.
 The cord is only about 1 foot long so it
doesn’t catch on things.
 When the unit is dropped, the skin around
the cord tears and becomes infected.
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Project Objectives

Create a breakaway port for power cable
that will detach with a certain amount of
force.
 Cable port is implanted where the cable leaves
the body
 Increase flexibility of cable and reduce stress on
surrounding skin

Create an internal power supply and motor
control unit for the pump when the cord
becomes disconnected.
 Backup power should last long enough for the
patient to seek assistance if something goes
wrong
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Detailed Design Review
Customer Needs
2/8/2013
Importance: 3=high,2=medium,1=low
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Detailed Design Review
2/8/2013
Engineering Specs
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Needs and Specs
Detailed Design Review
MSD Project 13022: Breakaway VAD
2/8/2013
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Detailed Design Review
2/8/2013
Notes






Is CN2 a redundant statement of CN1 and therefore
unnecessary? Wouldn’t a reduction of inflammation
be accomplished by reduced the force on the port?
CN5 is something that we may not be able to test or
implement. Therefore, is it necessary?
CN10 sounds like something that’s left up to the
surgeons. We can’t really test or implement this in a
practical manner…
CN12 is being removed because it is not our
concern. We will assume that there is no fluid or that
there are existing methods that can be implemented
to solve the situation.
S11 may be removed because it may be completely
unnecessary and we can’t test for it.
S2 is may not be considered a concern due to
physical observations of the current cord.
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Detailed Design Review
Chosen Concept
2/8/2013
Note: One of the
electrical methods has
changed. I believe it is
under “Manage
Switchover” > “Pump
Control Switchover” >
changed to “External
to Internal Relay”
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Detailed Design Review
2/8/2013
Block Diagram
Note: Some of the numbers of wires have been reduced.
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Detailed Design Review
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Specs vs Subcomponents
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Detailed Design Review
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Force Pull Test on Skin
0 degrees
45 degrees
90 degrees
Angle of
Disconnect
1
2
2.5
3
3.5
4
1
Displacement of
skin (mm)
1
5
10
10
12
15
-
2
-
light-med.
reasonable disconnect
3
4
5
1
-
medium
med-heavy
heavy
very light
upper limit
barely feel it
2
-
light
reasonable disconnect
3
4
5
-
medium
med-heavy
heavy
upper limit
Force (N)
Feeling Assessment
Comments
light
medium
med-heavy
heavy
too heavy
too heavy
light
Explain why upper and lower limits, and angle were chosen.
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Detailed Design Review
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Heat Analysis - Assumptions





Body Temperature (Environment) is 37˚C
Heat distribution on outside of device will
be modeled via FEA
Heat transfer method inside body is
conduction
All energy inefficiencies result in heat
generation
Device is surrounded my muscle tissue
which is at equilibrium between perfusion
and heat generation
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Detailed Design Review
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Heat Analysis – Additional 1D
Assumptions
1 dimension normal to the skin
 Uniform heat generation
 Constant Properties
 Body is at equilibrium (neglect heat
generation effects)
 Steady State

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Heat Analysis - Data










Reference Temperatures[C]:
Body Temp= 37 C
Ambient Air Temp= 25 C
Conduction Coefficients :
Internal Organs and Muscle = 0.500 W/m*K
Skin and Fat=0.300 W/m*K
Titanium=19.000 W/m*K (P13022 only)
Clothing=0.029 W/m*K
Convection Coefficients [W/m*K]:
Air=10.000
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Detailed Design Review
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Heat Analysis – Critical Values
The purpose of our thermal model is to
ensure this device will not harm the
patient.
With a factor of safety of 2, our maximum
heat flux through the tissue is
40mW/cm2
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Detailed Design Review
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Heat Analysis – 1D Analysis Model
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Detailed Design Review
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Heat Analysis - Results
Temperature Distribution
Heat Generation vs. Device Temperature at Contact
0.5
45
0.45
0.35
0.3
40
0.25
Q/Tair Curve
Heat Dissipated to Air
Q/Tbody Curve
Heat Dissipated to Body
Total Heat Dissipation
0.1
0.05
0
25
30
35
40
Temperature, T (C)
45
50
55
Heat Flux vs. Device Temperature at Contact
8
Temperature [C]
0.2
0.15
35
30
q=0.0W
q=0.1W
q=0.2W
q=0.3W
q=0.4W
q=0.5W
7
Heat Energy,q (mW/cm2)
Heat Energy,q (W)
0.4
6
5
25
4
3
Q/Tair Curve
Heat Flux Dissipated to Air
Q/Tbody Curve
Heat Flux Dissipated to Body
Total Heat Flux Dissipation
2
1
0
25
30
35
40
Temperature, T (C)
45
50
20
-0.04
55
MSD Project 13022: Breakaway VAD
-0.03
-0.02
-0.01
0
0.01 0.02
Distance across device, [m]
0.03
0.04
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Detailed Design Review
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Heat Analysis – Engineering Model
Boundary Temp: 37˚C
Device
Conduction
Internal Environment
(Abdomen Muscle)
•The Device will be implanted in abdomen muscle
•Assuming a worst case scenario, the device will be surrounded by muscle
tissue in all directions for an “infinite” thickness.
•An ANSYS model which includes the boundary temperature of 37˚C and all
muscle properties will show worst case temperature and flux conditions
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Detailed Design Review
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Heat Analysis - Summary
For the given area of 64cm2 , 0.3 W
(4.67mW/cm2) of heat generation will be
dissipated before exceeding 40oC.
 For a surface area of 340cm2 we should
be allowed to generate up to 13.6 W of
heat energy within the device.
 Expected worst case heat generation =
2 W.

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Detailed Design Review
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Heat Analysis - Conclusion





The Internal Battery Storage Device is not likely to
harm the body through heat generation based upon
the of energy flux through the total surface area.
Further analysis will be conducted (in ANSYS) to
confirm the results.
Due to the extreme difficulty of finding a relatively
accurate model for the body in relation to the LVAD
system, the 1-D analysis is only useful for worst case
results and only provide limited useful data.
Further analysis in ANSYS should provide more
reliable results.
Development of the P13022 device should continue
with minimal design change.
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Detailed Design Review
2/8/2013
Testing Plan
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Detailed Design Review
2/8/2013
Work Breakdown Structure
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Detailed Design Review
2/8/2013
System Model
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Detailed Design Review
2/8/2013
System Model (sketch)
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Detailed Design Review
2/8/2013
Internal Power Control (sketch)
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Detailed Design Review
2/8/2013
Breakaway Port Design
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Detailed Design Review
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Bill of Materials
Material:
Quantity:
Price per unit:
Total cost:
Comments:
Batteries
8
$3.50
$28.00
LiFePO4 18650 Rechargeable Cell: 3.2V
1500 mAh, 4.5A Rate, 4.32Wh, UL Listed,
UN Approved (NDGR) Part Number: LFP18650-1500
Polycarbonate/Acrylic
1
$0.00
$0.00
Old scrap piece will be used unless more
models needs to be made.
motor controller design board
1
$300.00
$300.00
used to design the motor controller
Bio-compatable titanuim
roundstock
1
$23.10
$23.10
For implant 1.25"D X 1.00"L
http://www.onlinemetals.com/merchant.cfm?
pid=6776&step=4&showunits=inches&id=18
7&top_cat=0
Recharge Board
1
$6.45
$6.45
PCB (Protection circuit module) for 4 cells
(12.8V) LiFePO4 Battery Part Number:
PCB-LFP12.8V2A
Surgical tubing
1
$30.39
$30.39
http://www.amazon.com/Latex-RubberSurgical-Tubing-39323932/dp/B0045V36PQ
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Detailed Design Review
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Bill of Materials (cont’d)
Material:
Quantity:
Price per unit:
Total cost:
Comments:
Wire
1
$13.15
$13.15
100ft, 16 gauge wire
Magnets
5
$1.00
$5.00
Microcontroller
2
$20.00
$40.00
Relay
1
$17.19
$17.19
Resistors
$0.00
Capacitors
$0.00
Thermocouple
$0.00
Connectors
$0.00
PBC board
1
$50.00
$50.00
Vibrating motor
2
$3.99
$7.98
10-pin connector
$0.00
Total:
$463.28
MSD Project 13022: Breakaway VAD
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Detailed Design Review
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System Model (sketch)
I love my new
breakaway
port system!
Hanzlik in 20 years.
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