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Electrophysiology
Paul Wang, MDAmin Al-Ahmad, MD
ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos
Power Steered Catheter Control System
Karlin Bark, Marlo Dreissigacker, Gabriel Sanchez, Dan Santos
Electrophysiology and Arrhythmia
• Electro-physiologists detect abnormal electrical pathways in the heart by recording electrical activity within the heart chambers
ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos
Non-Surgical Procedure
Catheter insertion point
ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos
Current State of the ArtManual
ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos
• Multi-Degree of Freedom– Bi-directional – Torsion Control– Telescoping Tip
• Increased Mapping Area– Ring of Contacts– Balloon Catheter
Current State of the ArtRobotic
• Hansen Medical– Robotically Controlled
Catheter
ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos
Clinical Need Finding• Surgeon “wish-list”
– More comfortable and simple to use– Easier control of distal tip– Finer positioning resolution of distal tip– Larger range of motion of distal tip– Tactile feedback
• Statements– “uncomfortable”, “tiring”, “fingers hurt”, “not intuitive at all”
ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos
Current design problems• Simple mechanical designs:
– Manual positioning limits accuracy– Physically taxing user-interface– Uncomfortable user-interface
• Advanced robotic designs:– Not intuitive– No direct tactile feedback– Requires re-training
ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos
Design Specifications• Focus on manual input device that doctor uses• Specifications:
– Electromechanical - Smart Mechanical Drive– Bi-directional control– One-handed operation - familiar to doctors– In-line structure – Non-backdriveable
ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos
Smart Mechanical Drive
ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos
Internal motor actuates push-pull cables based on doctor’s input
Power Steering
Input Mechanism
ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos
• Linear Slide• Axially Symmetric• Low Friction
Electronics
ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos
µControllerPIC
MotorDriver
LinearSensor
LimitSwitches
PowerSupply
• Proportional Speed Control• Dead-band Throttle• Travel Limits
Design Improvements
• Decrease overall size• Manual override• Increase speed
smaller diametershorter length
manual overridelarger pitch
spring mechanism
ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos
• Advanced Control• Self-Centering Ring
Conclusions
• Less physical effort to use• Similar motion and interface: no additional training• Could transition into real-world market easily
– Minor change on existing, common device– Only a small increase in cost
• +$50 for a device that costs $600-$1000+
ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos
Acknowledgements
• Dr. Paul Wang, Dr. Amin Al-Ahmed, Bryant Lin• Craig Milroy and Raj Doshi• Laura Melton
ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos