2011 Medical Micro Robot Workshop
Paper235
Intravascular Therapeutic Microrobot for Chronic Total Occlusion in Coronary Artery
Mar. 7. 2011
Jong-Oh Park, Dr.-Ing. Robot Research Initiative Chonnam National University
[email protected]
Outline
1
Project Description
2
In-Vivo Test in a Living Animal
3
Microrobot Locomotion
4
Thrombus and CTO Therapeutics
5
Imaging System
6
Micro Actuation
7
Future Work microrobot.re.kr
Intravascular Therapeutic Microrobot Drug Delivery and Therapy of Coronary Artery Disease Using Microrobot Spec.
D 1mm, L 10mm, Feed 50mm/min
Function Recognition, Locomotion, Therapy, Clinical Validation Disease
Chronic Total Occlusion, Thrombus, etc
microrobot.re.kr
Intravascular Microrobot System
H/W Platform
Electromagnetic Navigation System CT & X-ray Imaging System Microrobot Controller
S/W Platform
3D Vessel Reconstruction
Image Fusion(Registration)
Diagnosis
Microrobot Navigation
microrobot.re.kr
Main Research Fields
Imaging system & navigation S/W 3D Locomotion and control of robot Medical treatment Clinical validation
microrobot.re.kr
In-vivo test in a living animal(Minipig)
microrobot.re.kr
Microrobot Position Control & Tracking
Target region : Iliac artery Contents : 1. Microrobot Control in pulsating blood flow 2. 3D Position Tracking using registration method between CTA image(pre-op) & X-ray image(intra-op) microrobot.re.kr
Clot Destruction by Microrobot
Target region : Iliac artery phantom Contents : 1. Destruction of pseudo CTO Material (Agar 0.3%) 2. 3D Position tracking using registration method between CTA image(pre-op) and CCD image microrobot.re.kr
Microrobot Locomotion Magnetic Navigation System 1D
2D
3D
Drilling & Locomotion microrobot.re.kr
Microrobot Locomotion Helmholtz & Maxwell Coil • Helmholtz coil : Uniform Magnetic Field => To align microrobot • Maxwell coil : Uniform Gradient Magnetic Field => To propel Microrobot
d 3r
d r ROI
2 inr 1 1 H 3 3 2 2 d 2 d 2 r 2 z r z 2 2
Magnetic Field by Helmholtz coil
r schematic of Helmholtz and Maxwell coil
2 inr 1 1 H 3 3 2 2 d 2 2 d 2 r z r z 2 2
Magnetic Field by Maxwell coil microrobot.re.kr
Microrobot Locomotion 2D Magnetic Navigation System I 2Pair Stationary Coil System
(Smart Material and Structure, 2009)
•
Helmholtz and Maxwell coil pairs in X & Y axis
•
2D planar Motion
microrobot.re.kr
Microrobot Locomotion 2D Magnetic Navigation System II 2Pair Stationary Coil System
(Smart Material and Structure, 2009)
•
Helmholtz coil in X & Y axis and Maxwell coil in Z axis
•
2D planar motion
•
Smaller power consumption than the previous system Mx_z
Hz_x Hz_y
microrobot.re.kr
Microrobot Locomotion 3D Magnetic Navigation System I 3D Motion by Rotation of Coil System
(2009 IROS Conf.)
• 1D locomotion mechanism by Helmholtz and Maxwell coil is expanded to 3D spatial motion by using 3 rotational axis.
microrobot.re.kr
Microrobot Locomotion 3D Magnetic Navigation System II Novel EMA Method for 3D Motion (Sensor and Actuator, 2010) • 1 pair of stationary Hz, Mx and 1 pair of Rotational Hz, and Mx. • 3D motion by rotating Hz and Mx coil pairs
microrobot.re.kr
Microrobot Locomotion 3D Magnetic Navigation System III
Saddle Coil System (Sensor and Actuator, 2010) • 1 pair of stationary Hz and Mx coil • 1 pair of Rotational Uniform and Gradient saddle coil
• 3D motion by rotating saddle coil pairs
Schematic of Proposed EMA System
microrobot.re.kr
Microrobot Locomotion 3D Magnetic Navigation System III
Experimental Results Locomotion in Cube with Gravity Compensation
Locomotion in the Blood Vessel Phantom
microrobot.re.kr
Microrobot Locomotion Blood Flow Modeling I Object : Prediction of intravascular environment and precise dynamic modeling of microrobot Analysis of Blood Flow for Modeled Vessel • Analysis of blood flow for each geometrical shapes
Wall Pressure[Pa]
point 1
point 2
point 3
90deg
60deg
45deg
30deg
90deg
60deg
45deg
30deg
90deg
60deg
45deg
30deg
90deg
60deg
45deg
30deg
7 6 5 4 3 2 1 0
point 4
microrobot.re.kr
Microrobot Locomotion Blood Flow Modeling II Analysis of Blood Flow in Actual Blood Vessel Model • Vessel modeling with CT Data
• Analysis of blood flow in blood vessel
microrobot.re.kr
Microrobot Locomotion Blood Flow Modeling III Analysis of Pulsating Blood Flow • Lattice Boltzmann Method
• Pulsatile flow analysis • Drag force analysis for the circular and rectangular shape
microrobot.re.kr
Microrobot Locomotion Blood Vascular Simulator • Pulsating flow generation • Arch to iliac and coronary artery • Systole/diastole ratio control • Heart rate control • Blood pressure sensing
microrobot.re.kr
Microrobot Locomotion Overall Control System of Microrobot • Power Supply : 4(MX15pi, 3001i, and Agilent 6675) • Controller : NI PXI System • Position Recognition : CCD Imager
• Control S/W : Programed by LabVIEW Coil System
Imaging System
PXI Controller Power Supply
microrobot.re.kr
Microrobot Locomotion Control Algorithm • Uniform propulsive force by constant DC current input • Drag force compensation using pressure signal of pulsating flow • Feedback position control using position of microrobot
microrobot.re.kr
Microrobot Locomotion Drag Force Compensation Algorithm • The drag force of the microrobot in the fluid is expressed as,
• The blood flow has a same period as the pressure and the similar waveform in aorta from canine and human • Drag force compensation algorithm
microrobot.re.kr
Microrobot Locomotion Control Performance in In-vitro Condition DC current input
1 Drag force compensation
2 Feedback control
3 Fluctuation range 1, 19.9mm , 2. 4.6mm, 3. 1.5mm microrobot.re.kr
Microrobot Locomotion Control Performance in In-vivo Condition • Drag force compensation using blood pressure transducer • Feedfoward control and phase-shifting method
DC Continuous input Fluctuation : 51.4mm
Drag force compensation & Phase shifting method Fluctuation : 16.3mm microrobot.re.kr
Microrobot Locomotion MRI based Gradient MNS Advantages - Imaging & locomotion in One system Disadvantages - Unable to perform Rotational Motion of microrobot MRI Gradient MNS
Slow Z-X motion
Rapid Z-X motion
Maxwell Coil
Golay Coil microrobot.re.kr
Microrobot Locomotion Locomotion and Imaging Locomotion test in MRI Imaging System Phantom Image Microrobot
Robot Position Data Microrobot
microrobot.re.kr
Thrombus & CTO Therapeutics Debris Collecting
Drilling for CTO & Thrombus
Centering in Blood Vessel
Drug Delivery
microrobot.re.kr
Thrombus & CTO Therapeutics 2D Magnetic CTO Drilling I
CTO/Thrombus Drilling System ( URAI, 2009)
• 3 pair of Rectangular Helmholtz coil • Drilling and locomotion by rotating magnetic fields microrobot.re.kr
Thrombus & CTO Therapeutics
,
2D Magnetic CTO Drilling I Rectangular Helmholtz coil 2I a 2 1 Hh { [a 2 (z d / 2) 2 2a 2 (z d / 2) 2
a
z
i
d
1 [a (z d / 2) 2
2
2a (z d / 2) 2
2
}
Distance to generate Uniform Magnetic Field
i Schematic of Helmholtz coil
Magnetic Field by Rectangular Hz. microrobot.re.kr
Thrombus & CTO Therapeutics
,
2D Magnetic CTO Drilling I Rotational Magnetic Field
cos
sin
α
β
I x (t) I m, x {cos( )sin(t) cos( )cos( )cos(t)} 2 2 I y (t) I m, y {sin( )sin(t) sin( )cos( n )cos(t)} 2 2 I z (t) I m, z {sin( )sin(t)} 2 microrobot.re.kr
Thrombus & CTO Therapeutics
,
2D Magnetic CTO Drilling I Micro robot motion : Conchoids outer shell & Magnet D 2.5mm L 12 mm
Magnetization direction
Rotational magnetic field
+ magnet microrobot.re.kr
Thrombus & CTO Therapeutics 2D Magnetic CTO Drilling II 2D Enhanced Drilling System
(submitted in Sensor and Actuator, 2011)
• 3 pair of stationary Hz coil & 1 pair of Maxwell Coil along X axis • Maxwell Coil to increase the propelling force to drilling direction
I : Current value m : Magnitude of current ω : Angular velocity θ : Magnetization Direction α : Desired locomotion direction
microrobot.re.kr
Thrombus & CTO Therapeutics 2D Magnetic CTO Drilling II Configuration of EMA system and Microrobot Magnetization Direction(θ)
θ=90º
θ=0º
θ=45º
[Magnetization direction of the microrobot] ★ Microrobot included two magnets with different magnetization!
microrobot.re.kr
Thrombus & CTO Therapeutics 2D Magnetic CTO Drilling II Rotationg Precessional Magnetic Field Desired direction(α)
θ=45º, α=0º
Steering
Locomotion
θ=45º, α=30º
Drilling
Enhanced Microrobot microrobot.re.kr
Thrombus & CTO Therapeutics 2D Magnetic CTO Drilling II
- Rapid prototype (RP) - Empty inner space for the insertion of the two permanent magnets
- Diameter : 2.7mm - Spiral height : 0.7mm - Total length : 20mm
microrobot.re.kr
Thrombus & CTO Therapeutics 2D Magnetic CTO Drilling II * 2D Locomotion and Drilling Test
Microrobot Target Start
microrobot.re.kr
Thrombus & CTO Therapeutics 3D Locomotion and Drilling System 3D Locomotion and Drilling System(Sensor and Actuator, 2010) • 3 pair of stationary Hz coil • 1 pair of stationary Mx. and 1 pair rotatinal gradient saddle coil
Fabricated MNS
Schematics of MNS
Microrobot microrobot.re.kr
Thrombus & CTO Therapeutics 3D Locomotion and Drilling System Experimental Results
Agar Drilling
Cap Grinding Calcium carbonate CaCo3 microrobot.re.kr
Thrombus & CTO Therapeutics Magnetic CTO Tunneling Device Coil gun Type CTO Tunneling Mechanism - Motion : Impact Hammering motion (Initial path) + Twisting Motion (Widening path) - Input : Modulated Rectangular Wave (Impact motion)
+ Sine wave (Twisting motion) Input Signal
EMA
Motion
microrobot.re.kr
Thrombus & CTO Therapeutics CTO Tunneling Test -Robot : Cylinder & Bullet type 1mm(D)X5mm(L), 2mm(D)X5mm(L) -CTO model : 1% Agar & CaCo3 based CTO Cap -Results : Pathway in 210sec, Cap Destruction around 170sec Agar
Glycerin
Microrobot
-41-
microrobot.re.kr
Thrombus & CTO Therapeutics Ultrasonic CTO Tunneling Device Ultrasonic Wave Propagation Analysis -Horn Shape : Half-circle(D=20cm), Parabolic(D=10cm), Gaussian(D=4cm, 200kHz) Horn -Frequency : 20kHz
Horn
Freq.
Concentration Point
Half Circle D=20cm
20kHz
10cm from Horn
Parabolic D=10Cm
20kHz
4cm
Gaussian D=4cm
200kHz
4cm
microrobot.re.kr
Thrombus & CTO Therapeutics Ultrasonic CTO Tunneling Device Actuating Pressure Analysis on Target Region in Fluid (2D/3D) -Actuating Frequency : 20kHz -Media Fluid: Water(Blood) -Actuating Pressure : 7M Pa Ultrasonic Horn Design -Frequency : 20kHz, Material : Duralumin 7079 -Transducer type : BLT(Bolted Langevin type Transducer)
Quarter l
microrobot.re.kr
Thrombus & CTO Therapeutics Wired Solutions • Wired Microrobot for CTO Treatment • Function : Centering/Steering/Drilling • Diameter : 900mm
• Disease oriented Tool Module Drill Tip
Flexible Joint
Driving & Control Unit
Flexible Probe Probe Tip with 1-1.5mm D
Probe Tip with 1.7-2.5mm D microrobot.re.kr
Thrombus & CTO Therapeutics Drilling Tool • Four types of tool pattern
• Tool Diameter : 2mm, Revolution speed : 30,000rpm • Material : HA/PLA composite (CTO model)
Y
Z
X
0.5 mm
• Cutting Force Measurement with Low/High pass filtering
Tool Pattern I
Tool Pattern III
Tool Pattern II
Tool Pattern IV microrobot.re.kr
Thrombus & CTO Therapeutics Porous Hydroxyapatite(Pseudo CTO Model) • CTO Property Calcified Deposit (mostly hydroxyapatite)
Intimal Plaque (cholesterol, lipids)
Chemical Components
Percent (%)
Delipidized arterial tissue
34
Free cholesterol
2
Cholesterol esters
10
Triglycerides & phospholipids
0
Calcium salts (Hydroxyapatite)
54
[Romer et al., Circulation, 1998]
• Porous hydroxyapatite - Pseudo CTO Material with similar mechanical property for drilling test
9.7mm
25mm
Mechanical properties of Vertebral trabeculae & Porous hydroxyapatite by nanoindentation
Material
Modulus (GPa)
Hardness (MPa)
Vertebral trabeculae*
13.4±2.0
468±79
Porous hydroxyapatite
10.6±0.8
219±28
[* Rho et al., Biomaterials, 1997]
microrobot.re.kr
Thrombus & CTO Therapeutics Animal CTO Model induced by L-PLA • Animal : Pig(Female, 25-30 Kg) • Realization of similar condition of human CTO • Ex-vivo test for microrobot function (will be used)
Baseline
After embolization
4 weeks later
microrobot.re.kr
Thrombus & CTO Therapeutics Drug Delivery • Steptokinase(SK) loaded Gelatin nano particle : Resolution test for Thrombus
• Bio degradable Nano PLGA(Poly Lactic Glycolic Acid) Nano Particle
Micro Particle
- Optimized drug carrier for thrombus - Micro particle : 1~3 μm - Nano particle : 200~300 nm microrobot.re.kr
Imaging and Navigation System 3D Vascular Model using CTA/MRA Data • 3D image reconstruction from CT Image • Segmentation for interesting region
• Reference model for intravascular navigation of microrobot 3D Image (Reconstruction)
3D Image (Segmentation Image)
microrobot.re.kr
Imaging and Navigation System Diagnosis S/W • Diagnosis using 2D/3D image data • Definition of target destination of microrobot
• Simulation of microrobot moving to destination Diagnosis & Moving Path 3D CT Images
Simulation of microrobot Moving
microrobot.re.kr
Imaging and Navigation System 3D Position Recognition of Microrobot • Real-time 3D position recognition of microrobot in living body • Registration of intra-op(X-ray) images to pre-op(CT/MRA) images
• Gold fiducial markers was inserted to subcutaneous tissue for registration Mapping Fiducial Marker
Image Registration
Robot Tracking microrobot.re.kr
Imaging and Navigation System 3D Position Recognition of Microrobot • Real-time 3D position recognition & monitoring of microrobot
microrobot.re.kr
Micro Actuation Ferropaper • Paper(fiber array) based Actuator • Driven by Electromagnetic field • Direction Control by soft magnetic property • Pros : Small, Light, and Rapid Response, easy fabrication
• Cons : Small actuation force, depend on EM field
microrobot.re.kr
Micro Actuation Jellyfish Robot Mechanism
• Aquatic microrobot with jelly fish like motion • Driven by alternating electromagnetic field generated from 3 Hz coils • PDMS body fabricated by casting method
1. 2. 3. 4. 5.
Current input Magnetic Field Alignment Torque generation Propulsion
Bending Analysis
Fabricated robot microrobot.re.kr
Micro Actuation Jellyfish Robot
3Axis Helmholtz
Experiment in Water
microrobot.re.kr
Micro Actuation Swimming Microrobot • Tadpole type swimming robot • Driven by alternating magnetic fields generated by 2 pair Helmholtz coil • Swimming speed and direction control by magnetic field modulation
Motion Mechanism
Robot Structure Control System microrobot.re.kr
Future Work
Focus on CTO Therapeutics
Theoretical Analysis of Microrobot Movement in Pulsating Blood Flow Integration of H/W Platform Self-Locomotion of Microrobot
Gracie ! microrobot.re.kr
