in-vivo device for measuring and adjusting lap-band pressure john huidekoper mark fritz chris...
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![Page 1: In-vivo Device for Measuring and Adjusting Lap-Band Pressure John Huidekoper Mark Fritz Chris Schroeder Andrew Koivuniemi David Mayhew ©Bill Watterson](https://reader036.vdocument.in/reader036/viewer/2022062422/56649eef5503460f94bff21a/html5/thumbnails/1.jpg)
In-vivo Device for Measuring and Adjusting Lap-Band Pressure
John HuidekoperMark FritzChris SchroederAndrew KoivuniemiDavid Mayhew
©Bill Watterson
Advisors:Dr. Robert RoselliDr. Thomas Rauth
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Background Information
Obesity in United States Obese
30 pounds overweight Morbidly obese
100 pounds overweight Or BMI over 40 Effects 9 million Americans
BMI Body Mass Index (Weight*703)/(height^2)
Sources of help Gastric Bypass Lap-Band
Source:http://www.sptimes.com/2003/10/14/Worldandnation/Number_of__extremely_.shtml
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Reasons for Design Choices
Problems Device Failure
Leaks (Maude Database) Patient Pain
No Constant Pressure Fixes
Implantable Pump Autonomous Control as
well as Non-Invasive Control
0
100
200
300
400
500
600
Me
an B
and
Pre
ssur
e (
mm
Hg
)
0 1 2 3 4Adjustment Number
press Opening PressureFinal Pressure
Pressure Degradation between Adjustments
Ref: Research done by Dr. Thomas Rauth
![Page 4: In-vivo Device for Measuring and Adjusting Lap-Band Pressure John Huidekoper Mark Fritz Chris Schroeder Andrew Koivuniemi David Mayhew ©Bill Watterson](https://reader036.vdocument.in/reader036/viewer/2022062422/56649eef5503460f94bff21a/html5/thumbnails/4.jpg)
Ideas we’ve tossed out
External control Problems Still have problems
with the port Patients could
unhook the device if uncomfortable
http://www.minimed.com/images/x22_features_callout.jpg
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Ideas we’ve tossed out
Syringe pump Dead space behind it No mechanical
advantage The ones out there are
too large for implantation
http://www.klf-insurance.com/images_for_site/syringe.jpg
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Basis of our ideas
Car-jack Pacemaker Squeezing on fluid
bag
http://www.syncope.co.uk/images/Pacemaker.JPG
http://www.3dkingdom.org/modules/My_eGallery/gallery/models/thumb/CarJackModel.jpg
http://www.uthscsa.edu/mw/photogallery/Media/biomed/images/IV_BAG.jpg
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Current Pump Design
Design Parameters Fluid pressure
Max at 2 atm
Screw Torque Max at 4 Nm
Considerations Bi-directional adjustment Space-saving design Torque profile
![Page 8: In-vivo Device for Measuring and Adjusting Lap-Band Pressure John Huidekoper Mark Fritz Chris Schroeder Andrew Koivuniemi David Mayhew ©Bill Watterson](https://reader036.vdocument.in/reader036/viewer/2022062422/56649eef5503460f94bff21a/html5/thumbnails/8.jpg)
Torque Considerations
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Current Pump Design
![Page 10: In-vivo Device for Measuring and Adjusting Lap-Band Pressure John Huidekoper Mark Fritz Chris Schroeder Andrew Koivuniemi David Mayhew ©Bill Watterson](https://reader036.vdocument.in/reader036/viewer/2022062422/56649eef5503460f94bff21a/html5/thumbnails/10.jpg)
Motors
Stepper motors Provides fine tuning
in angular position Good with micro-
controller Provides detent
torque Prototyping
Use a DC motor
www.wikipedia.com/
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Motor Selected
Micromo AM 2224 DC Motor Low Voltage = Low
RPM = Max Torque
2 cm diameter 4 cm long Price : $185.88
www.portescap.com/
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Gearing
Advantages Increased Torque Increased Precision
Disadvantage Occupies Space Less Efficient
Tried to make our own
Problem- Small Gears are very expensive
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Our Gears
Gearhead Attaches to the front
of the motor Increases the torque
several orders of magnitude (1000:1)
4.5 NM torque Does increase motor
length to 7 cmwww.portescap.com/
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Safety
Used Design Safe Software Filled out the possible problems and
solutions Conclusions
Most important to have a durable casing Have a long battery life Situate device far from vital organs Provide fail safe if program fail
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Necessity of Pump Control
Desired Curve
Pressure Adjustment
Loss of PressureRauth, Thomas. “Why use Pressure Directed Lap-Band Adjustment?” Vanderbilt Center for Surgical Weight Loss, Nashville, TN. 17 Oct. 2006.
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RF Control ChipNegative Feedback Control
Pressure Drop in Lap-Band
Pressure TransducerDetects Changes
Data Processing of Multiple Readings
Chip Determines Necessary Volume
Pump Changes VolumeOf Saline in Lap-Band
-
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Bag to Hold Saline
Saline-Filled Bag
Exploring several options:1) Bag Material2) Bag Fabrication
Prototype Pump-Easily disassembled-Experiment with bag designs
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Progress Summary
Pump Design Pump Fabrication Electronics (Chip, Pressure
Transducer, Battery, Motor Control) Bag Design/Fabrication