Catheter Guidewire Control System Derek Carlson Caleb Anderson
Catheter Guidewire Control System Derek Carlson & Caleb Anderson Advisors: Dr. Dempsey & Dr. Stewart
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/ ME’s – Conclusions Questions?
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
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.
Overall Block Diagram
Electroactive Polymer • Material purchased from Environmental Robots, Inc by the Mechanical Engineering department • Responds to a DC voltage between -5 V to 5 V • +-5 V results in an approximate 90 degree bend • Tip will be made of this material for precision control
Electroactive Polymer Characteristics • 2 kinds of polymer available – Platinum plated – Gold plated • We discussed testing procedures with the ME’s. – They returned voltage vs. curvature data for both types of polymer • Results
Gold Polymer Voltage vs. Deflection Angle Voltage vs. Angle of Deflection R 2 = 0, 9858 R 2 = 80 Deflection Angle 80 70 60 50 40 30 20 10 10 0 1, 5 2 2, 5 Voltage 3 3, 5 4 4, 5 0 -4, 5 -3, 5 Voltage -2, 5 -1, 5
Polymer Run Times Platinum Plated Run # 1 2 3 4 5 6 Time (Minutes) 4: 50 4: 25 4: 12 3: 51 3: 42 3: 37 Time Lasted Per Run: 04: 06 Run # 1 2 3 4 5 6 Time (Minutes) 3: 50 3: 30 3: 12 3: 02 2: 48 2: 42 Time Lasted Per Run: 03: 10 Gold Plated Run # 1 2 3 4 5 6 Time (Minutes) 7: 50 7: 25 7: 08 6: 35 6: 17 5: 56 Time Lasted Per Run: 6: 51 Run # 1 2 3 4 5 6 Time (Minutes) 7: 38 7: 32 7: 19 6: 52 6: 36 6: 06 Time Lasted Per Run: 7: 00
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
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?
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
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/ ME’s – Conclusions Questions?
Amplifier Circuit • Frequency Response 20 Hz – 20 k. Hz • Minimum Gain of 10 for no oscillation • Non-inverting so unity at DC • Mute needs 0. 5 m. A
Overall Block Diagram
Motor Controller Board • Runs off of a USB-Serial driver • Dual supply mode • 2 motors connected draw roughly 1 amp when running • Controlled via MATLAB’s serial communication tools
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.
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 Bi. Step controller board tested and functional
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
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 • • •
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)
Collaborative Progress • Several meeting have been held with ME’s – Shielding concerns have been discussed – Medical grade wire for supply of power – Electrically conductive adhesive for connecting polymer to wire – Test system construction • ME’s focused on prototype guidewire – Our focus was on control system
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
Questions?
- Slides: 24