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 data Platinum vs. Gold • Derek Carlson – – – – • Motor Controller Board Stepper Motors MATLAB progress GUI Updated Equipment List Updated Foreseeable Difficulties Schedule Collaborative Progress w/ ME’s 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 will be implemented using a joystick interfaced with MATLAB • A purchased controller board will run 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

Platinum Polymer Positive

Platinum Polymer Negative

Gold Polymer Positive

Gold Polymer Negative

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

Contents • Caleb Anderson – – – Overview of Catheterization Project Summary Overall Block Diagram Electroactive Polymer data Platinum vs. Gold • Derek Carlson – – – – • Motor Controller Board Stepper Motors MATLAB progress GUI Updated Equipment List Updated Foreseeable Difficulties Schedule Collaborative Progress w/ ME’s Questions?

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.

Stepper Motor Specs • Stepper Motor • • • • • • Excellent for precision control Can be operated in forward/reverse mode Excellent torque/size ratio Wide variety of supply voltages Data sheet included Dual shaft Check for compatible power supplies Step angle: 0. 9 degrees No. of phases: 2 Drive System: Bipolar Voltage(VDC): 8. 4 Phase resistance (Ω): 30 Current (m. A): 280 Phase Inductance (m. H): 25 Detent torque(g-cm): 36 Holding Torque(g-cm): 791 Mounting hole space digonal (in. ): 1. 73 Mounting hole (in. ) 0. 15 Shaft diameter (in. ): 0. 155 Shaft length(in. ): . 29 Motor diameter (in. ) 1. 64 Motor height (in. ) 1. 20 Weight: 0. 53 lbs. Jameco P/N 163395 MOTOR, STEP, 8. 4 VDC, 30 ohm. 9 deg, SHFT: . 16"X. 39" www. Jameco. com

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 • Documentation of MATLAB GUIde environment • 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 because of speed of computer

Updated Equipment List • • (2) 1 degree stepper motors (Jameco motors) (1) Bistep Motor Controller Board (1) Electroactive polymer tip (1) Surgical Guidewire (2) DC voltage sources (1) PC USB Webcam (1) Logitech Wingman Pro Attack 2 Joystick (2) Metal pulley wheels with tight rubber belts • For gripping of the guidewire

Updated Foreseeable Difficulties • Polymer current draw was very high on large pieces (0. 5 A) – Shielding will be a large problem inside of a human body. – UPDATE: Shielding solutions have been discussed and researched with the ME students. • Polymer functionality highly dependent upon moisture – This may be because we have worked with old and mistreated polymer samples. – UPDATE: New samples of polymer react better. There still is an issue of timing though. • Rotation and advancement of guidewire may be tricky to perform without damaging guidewire • UPDATE: Rubber wheel will be used to directly grip guidewire without damage.

Updated 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 • Meetings 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 • New samples of polymer were ordered and received as of last week – These samples are for our exclusive use

Questions?