intravascular therapeutic microrobot for chronic total … · · 2011-06-23intravascular...

Mar. 7. 2011

Jong-Oh Park, Dr.-Ing. Robot Research Initiative

Chonnam National University [email protected]

2011 Medical Micro Robot Workshop

Intravascular Therapeutic Microrobot for Chronic Total Occlusion in Coronary Artery

r

텍스트 상자

Paper235

microrobot.re.kr

Outline

In-Vivo Test in a Living Animal

Thrombus and CTO Therapeutics

Microrobot Locomotion

1

2

4

3

Imaging System

Micro Actuation

5

6

Future Work 7

Project Description

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

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Intravascular Microrobot System

Electromagnetic Navigation System

CT & X-ray Imaging System Microrobot Controller

H/W Platform S/W Platform

3D Vessel Reconstruction

Image Fusion(Registration)

Diagnosis

Microrobot Navigation

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Main Research Fields

Imaging system & navigation S/W

3D Locomotion and control of robot

Medical treatment

Clinical validation

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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)

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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


1D 2D

3D

Drilling & Locomotion

Magnetic Navigation System

microrobot.re.kr


Helmholtz & Maxwell Coil

• Helmholtz coil : Uniform Magnetic Field => To align microrobot

• Maxwell coil : Uniform Gradient Magnetic Field => To propel Microrobot

schematic of Helmholtz and Maxwell coil

rd

r

rd 3

2

3 3

2 22 2

1 1

2

2 2

i n rH

d dr z r z

2

3 3

2 22 2

1 1

2

2 2

i n rH

d dr z r z

Magnetic Field by Helmholtz coil

Magnetic Field by Maxwell coil

ROI

microrobot.re.kr

2Pair Stationary Coil System (Smart Material and Structure, 2009)

• Helmholtz and Maxwell coil pairs in X & Y axis

• 2D planar Motion


2D Magnetic Navigation System I

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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


2D Magnetic Navigation System II

Hz_y

Hz_x

Mx_z

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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.


3D Magnetic Navigation System I

microrobot.re.kr

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


3D Magnetic Navigation System II

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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


3D Magnetic Navigation System III

Schematic of Proposed EMA System

현철자료/현철_saddle.wmv

microrobot.re.kr

Experimental Results


3D Magnetic Navigation System III

<1 sec> <8 sec>

<16 sec>

Locomotion in the Blood Vessel

Phantom

Locomotion in Cube with

Gravity Compensation

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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

0

1

2

3

4

5

6

7

30deg

45deg

60deg

90deg

30deg

45deg

60deg

90deg

30deg

45deg

60deg

90deg

30deg

45deg

60deg

90deg

point 1 point 2 point 3 point 4

Wall Pressure[Pa]


Blood Flow Modeling I

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Analysis of Blood Flow in Actual Blood Vessel Model

• Vessel modeling with CT Data

• Analysis of blood flow in blood vessel

<Wall Sheer Stress>


Blood Flow Modeling II

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Analysis of Pulsating Blood Flow

• Lattice Boltzmann Method

• Pulsatile flow analysis

• Drag force analysis for the circular and rectangular shape


Blood Flow Modeling III

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Blood Vascular Simulator


• Pulsating flow generation

• Arch to iliac and coronary artery

• Systole/diastole ratio control

• Heart rate control

• Blood pressure sensing

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Overall Control System of Microrobot


Power Supply

PXI Controller

Coil System

• Power Supply : 4(MX15pi, 3001i, and Agilent 6675)

• Controller : NI PXI System

• Position Recognition : CCD Imager

• Control S/W : Programed by LabVIEW

Imaging System

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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

• 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

Drag Force Compensation Algorithm


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Control Performance in In-vitro Condition


Drag force compensation

Feedback control

DC current input

Fluctuation range 1, 19.9mm , 2. 4.6mm, 3. 1.5mm

1

2

3

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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

MRI based Gradient MNS

Maxwell Coil

Golay Coil

MRI Gradient MNS


Advantages - Imaging & locomotion in One system Disadvantages - Unable to perform Rotational Motion of microrobot

Slow Z-X motion

Rapid Z-X motion

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Locomotion test in MRI Imaging System

Phantom Image

Robot Position Data

Locomotion and Imaging


Microrobot

Microrobot

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Thrombus & CTO Therapeutics

Drilling for CTO & Thrombus

Centering in Blood Vessel

Debris Collecting

Drug Delivery

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CTO/Thrombus

Drilling System

( URAI, 2009)

• 3 pair of Rectangular

Helmholtz coil

• Drilling and

locomotion by

rotating magnetic

fields

2D Magnetic CTO Drilling I


microrobot.re.kr

Rectangular Helmholtz coil

,

d

a

i

zDistance to generate Uniform Magnetic Field

Schematic of Helmholtz coil Magnetic Field by Rectangular Hz.

})2/dz(a2)2/dz(a[

1

2222

2222

2

h

)2/dz(a2)2/dz(a[

1{

aI2H

i



microrobot.re.kr

Rotational Magnetic Field

,

α β t)})sin(

2{sin(I (t)I

t)})cos(2

)cos(sin( t))sin(2

{sin(I (t)I

t)})cos(2

)cos(cos( t))sin(2

{cos(I (t)I

z m,z

ny m,y

xm,x

sin

cos



microrobot.re.kr

Micro robot motion : Conchoids outer shell & Magnet

D 2.5mm L 12 mm

,

Rotational magnetic

field

magnet

Magnetization direction



+

microrobot.re.kr

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


2D Magnetic CTO Drilling II

I : Current value

m : Magnitude of current

ω : Angular velocity

θ : Magnetization Direction

α : Desired locomotion direction

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Magnetization Direction(θ)

θ=90º θ=0º θ=45º

[Magnetization direction of the microrobot]

★ Microrobot included two magnets with different magnetization!

Configuration of EMA system and Microrobot



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Steering Enhanced

Microrobot Locomotion Drilling

θ=45º, α=0º θ=45º, α=30º

Desired direction(α)

Rotationg Precessional Magnetic Field



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- 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

Start

Target

Microrobot

* 2D Locomotion and Drilling Test



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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

3D Locomotion and Drilling System


Fabricated MNS

Microrobot Schematics of MNS

충선자료/충선동영상.wmv

microrobot.re.kr

Experimental Results

3D Locomotion and Drilling System


Agar Drilling

Cap Grinding Calcium carbonate CaCo3

microrobot.re.kr

Magnetic CTO Tunneling Device

Coil gun Type CTO Tunneling Mechanism

EMA

Input Signal

- Motion : Impact Hammering motion (Initial path)

+ Twisting Motion (Widening path)

- Input : Modulated Rectangular Wave (Impact motion)

+ Sine wave (Twisting motion)

Motion


microrobot.re.kr

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

Microrobot

Glycerin

-41-


Agar_2x5.AVI

Chalk_1.46mm.AVI

microrobot.re.kr

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


Ultrasonic CTO Tunneling Device

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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


Ultrasonic CTO Tunneling Device

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Wired Solutions

• Wired Microrobot for CTO Treatment

• Function : Centering/Steering/Drilling

• Diameter : <3mm, Length >900mm

• Disease oriented Tool Module


Flexible Probe

Driving & Control Unit

Probe Tip with 1-1.5mm D

Probe Tip with 1.7-2.5mm D

Flexible Joint

Drill Tip

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Drilling Tool


• Four types of tool pattern

• Tool Diameter : 2mm, Revolution speed : 30,000rpm

• Material : HA/PLA composite (CTO model)

• Cutting Force Measurement with Low/High pass filtering

Tool Pattern I Tool Pattern II

Tool Pattern IV Tool Pattern III

0.5 mmX

Y

Z

microrobot.re.kr

Porous Hydroxyapatite(Pseudo CTO Model)


Chemical Components Percent (%)

Delipidized arterial tissue 34

Free cholesterol 2

Cholesterol esters 10

Triglycerides & phospholipids 0

Calcium salts (Hydroxyapatite) 54

Calcified Deposit

(mostly hydroxyapatite)

Intimal Plaque

(cholesterol, lipids)

Calcified Deposit

(mostly hydroxyapatite)

Intimal Plaque

(cholesterol, lipids)

[Romer et al., Circulation, 1998]

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]

Mechanical properties of Vertebral trabeculae & Porous

hydroxyapatite by nanoindentation 25mm

9.7

mm

• CTO Property

• Porous hydroxyapatite - Pseudo CTO Material with similar mechanical property for drilling test

microrobot.re.kr

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

Drug Delivery


• Steptokinase(SK) loaded Gelatin nano particle

: Resolution test for Thrombus

Nano Particle

Micro Particle - Optimized drug carrier for

thrombus - Micro particle : 1~3 μm - Nano particle : 200~300 nm

• Bio degradable Nano PLGA(Poly Lactic Glycolic Acid)

microrobot.re.kr

3D Vascular Model using CTA/MRA Data

Imaging and Navigation System

• 3D image reconstruction from CT Image

• Segmentation for interesting region

• Reference model for intravascular navigation of microrobot

3D Image (Reconstruction)

3D Image (Segmentation Image)

혈관_X-Ray Angio.wmv

microrobot.re.kr

Diagnosis S/W

• Diagnosis using 2D/3D image data

• Definition of target destination of microrobot

• Simulation of microrobot moving to destination

Diagnosis & Moving Path Simulation of microrobot

Moving 3D CT Images


microrobot.re.kr

3D Position Recognition of Microrobot

Image Registration

Fiducial Marker

Robot Tracking

Mapping


• 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

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3D Position Recognition of Microrobot

• Real-time 3D position recognition & monitoring of microrobot


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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

Jellyfish Robot

Micro Actuation

1. Current input 2. Magnetic Field 3. Alignment 4. Torque generation 5. Propulsion

Mechanism • Aquatic microrobot with jelly fish

like motion

• Driven by alternating

electromagnetic field generated

from 3 Hz coils

• PDMS body fabricated by casting

method

Bending Analysis Fabricated robot

microrobot.re.kr

Jellyfish Robot

Micro Actuation

3Axis Helmholtz Experiment in Water

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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

Micro Actuation

Robot Structure

Motion Mechanism

Control System

mmc1.mpeg

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 !

intravascular therapeutic microrobot for chronic total … · · 2011-06-23intravascular...

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