Tailor-Made and Biodegradable Vascular Scaffolds - Microsurgery: Advances, Simulations, and Applications - page 292

8.7.7 MSP Steering Principle, Modeling and Evaluation

8.7.7.1 MSP magnetically steering principle
Three-dimensional, in vivo remote magnetic manipulation of small
object have been demonstrated in cardiac catheterization, active
exploration of human gastrointestinal tract and for delivering drugs,
hyperthermia and other therapies within biological systems [46-49].
Here, a combined structure of Maxwell coils and Helmholtz coils is
used to generate gradient magnetic ield at arbitrary direction in Y-Z
plane of working area. As the central area of Maxwell coils is a low
ield area, where magnetic torque on MSP can be neglected but the
intensity of magnetic ield increases and the direction changes when
the MSP is away from the central area, this may result in unnecessary
rotation on MSP and malfunction of actuating MSP moving to the
opposite direction. Thus Helmholtz coils is introduced to add a
uniform magnetic ield to augment the magnetic ield intensity
in target area. For achieving a robust system to realize effective
controllability of MSP in hexane, a magnetic ield generator structure
combined Maxwell coils and Helmholtz coils is proposed as shown
in Fig. 8.28. Coils with the radius of R1 and R2 are Maxwell coils and
Helmholtz coils, respectively, with the axial direction aligned with Y
axis. Similarly coils with the radius of R3 and R4 are Maxwell coils and
Helmholtz coils, respectively, with the axial direction aligned with Z
axis. Arbitrary direction gradient magnetic ield can be achieved at
Y-Z plane by properly coniguring the input current for each coil.

Vision
System for
Feedback
Control

Z

R 4

Magnetized
Vasculature
Model

X

MSP Steered with
Magnetic Field

R 3

Y

R 2

MSP

Syringe Pump

B x

R 1

L 2

L 1

B z

a) b)

Figure 8.28 (a) Schematic of magnetic steering system for MSP. (b)
Combined structure of Maxwell coils and Helmholtz coils for
3D manipulation of MSP.