Catheter Guidewire Control System

1
Catheter Guidewire Control System

• Derek Carlson Caleb Anderson
• Advisors Dr. Dempsey Dr. Stewart

2
Contents

• Caleb Anderson
• Overview of Catheterization
• Project Summary
• Overall Block Diagram
• Electroactive Polymer
• Polymer data
• Platinum vs. Gold
• Microcontroller Development board
• Derek Carlson
• Amplifier Circuit
• Motor Controller Board
• Stepper Motors
• MATLAB progress
• Final Equipment List
• Schedule
• Collaborative Progress w/ MEs
• Conclusions
• Questions?

3
Overview of Catheterization

• Currently requires the use of multiple guidewires
• Guidewire allows easy travel to area of blockage
• Catheter slides directly over guidewire
• Guidewire is then removed from vessel

• www.forsythradiology.com

• www.amplatzer.com

4
Project Summary

• Eliminate the need for different guidewires
• Add precision control to the guidewire itself.
• Add remote control to the guidewire simply by
  viewing the patient through a camera.
• Control is implemented using a joystick
  interfaced with Matlab.
• A purchased controller board runs two stepper
  motors.
• These stepper motors will be used for lateral
  motion and guidewire advancement.
• A voltage reactive polymer will be used for
  precision tip control.

5
Overall Block Diagram
6
Electroactive Polymer

• Material purchased from Environmental Robots, Inc
  by the Mechanical Engineering department
• Responds to a DC voltage between -5V to 5V
• -5V results in an approximate 90 degree bend
• Tip will be made of this material for precision
  control

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Electroactive Polymer Characteristics

• 2 kinds of polymer available
• Platinum plated
• Gold plated
• We discussed testing procedures with the MEs.
• They returned voltage vs. curvature data for both
  types of polymer
• Results

8
Gold Polymer
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Polymer Run Times
Platinum Plated
Gold Plated
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Platinum vs. Gold

• Discussed results with ME students
• Linearity issues
• Runtime
• Current Draw
• Gold polymer was decided upon
• Runtime was the largest reason
• Slightly more linear as well
• Did not have quite as large of an angle of
  deflection

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Polymer Characteristic Problems

• Polymer behavior is not uniform
• Polymer to polymer
• Multiple runs same polymer
• Voltage response highly nonlinear
• Earlier results?
• DC voltage only test signal of value
• Other test signals?

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80535 Microcontroller Development Board

• D/A used to create 0 to 5 volt test signal
• 2 methods of input
• Keypad
• Joystick
• 0-100 Entry
• LCD Readout

13
Contents

• Caleb Anderson
• Overview of Catheterization
• Project Summary
• Overall Block Diagram
• Electroactive Polymer
• Polymer data
• Platinum vs. Gold
• Microcontroller Development board
• Derek Carlson
• Amplifier Circuit
• Motor Controller Board
• Stepper Motors
• MATLAB progress
• Final Equipment List
• Schedule
• Collaborative Progress w/ MEs
• Conclusions
• Questions?

14
Amplifier Circuit

• Frequency Response 20 Hz 20 kHz
• Minimum Gain of 10 for no oscillation
• Non-inverting so unity at DC
• Mute needs 0.5 mA

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Overall Block Diagram
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Motor Controller Board

• Runs off of a USB-Serial driver
• Dual supply mode
• 2 motors connected draw roughly 1 amp when
  running
• Controlled via MATLABs serial communication
  tools

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Stepper Motors

• Used for rotation and advancement of guidewire
• (2) Jameco 8.4 V motors ordered
• Suggested in Motor Controller Board documentation
• Tested with Motor Controller board
• Full functionality achieved
• Total current draw roughly 1 amp while running.

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MATLAB progress

• Serial control of board completed in command-line
  form
• Able to move motors independently
• Can move motors a certain distance, and then have
  them return
• All commands documented in BiStep controller
  board tested and functional

19
MATLAB GUI progress

• Basic GUI designed
• Layout including buttons for advancement and
  retraction of guidewire
• Command line interface for testing
• Webcam function via command buttons
• Webcam is functional separately, has not been
  implemented into GUI at this point

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Final Equipment List

• (2) 1 degree stepper motors
• (1) Bistep Motor Controller Board
• (1) Electroactive polymer tip
• (1) Surgical Guidewire
• (3) DC voltage sources (2) for motor control
  (1) for op-amp.
• (1) PC USB Webcam
• (1) Logitech Wingman Pro Attack 2 Joystick
• TBA mechanical system to test guidewire

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Completion of Schedule

• Weeks 1-3
• Stepper motor MATLAB interface (Derek Caleb)
• Webcam MATLAB interface (Caleb)
• RS-232 MATLAB interface (Derek)
• Weeks 4-6
• GUI for user input (Both)
• Develop polymer electrical characteristics (Both)
• Detailed current draw calculations
• Weeks 7-8
• Develop power electronics to actuate polymer
  (Derek)
• Possible polymer shielding concerns (Caleb)
• Weeks 9-10
• Stepper motor physical interface (Caleb)
• Guidewire drive system (propulsion, rotation,
  etc.) (Derek)
• Weeks 11-14
• Build test system (Both)
• Finalize report Presentation(Both)

22
Collaborative Progress

• Several meeting have been held with MEs
• Shielding concerns have been discussed
• Medical grade wire for supply of power
• Electrically conductive adhesive for connecting
  polymer to wire
• Test system construction
• MEs focused on prototype guidewire
• Our focus was on control system

23
Conclusions

• Electroactive polymers very promising for use in
  the medical field
• Gold plated polymer used for guidewire tip
  control is not developed enough for use
• Material is unpredictable and inconsistent
• Further research and development necessary to
  generate more useful polymer
• Other polymers may exist that would respond better

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Questions?