Tailor-Made and Biodegradable Vascular Scaffolds - Microsurgery: Advances, Simulations, and Applications - page 296

Figure 8.31 Relation between velocity of MSP and drag force.

8.7.7.5 Calculation of magnetic field

The distribution of magnetic lux density of Maxwell coils along
the axial direction is illustrated in Fig. 8.32. The magnitude of the
magnetic lux density varies linearly inside the two coils. A group
of Maxwell coils is used to generate the required gradient magnetic
ield; the parameters are 55 mm in diameter and 80 mm 2 in the area
of cross section. The calculation results shown in Fig. 8.32 show the
magnetic lux density increase in proportion to the input current
density. Different magnetic force can be obtained by adjusting the
input current of Maxwell coils to generate different gradient magnetic
ield. The value of J 0 is 4.0 × 10 6

A/m 2 , which is the maximum input
current density for general copper wire. When the value is set to J 0 , the
gradient of magnetic lux intensity in working area is approximately
equal to 330

mT/m, which is suficient to drive the MSP moving in
the hexane at a desired trajectory.
A group of Helmholtz coils is used to generate required uniform
magnetic ield. Figure 8.33 illustrates the magnetic lux density of
Helmholtz coils in axial directions. The magnitude of magnetic lux
density varies with the differences of coordinate in axial direction,
and a high degree of uniformity is achieved in the central region of
-0.02 to 0.02 m. The parameters are 95 mm in diameter and 80 mm 2
in the area of cross section. Figure 8.33 shows the magnetic lux
density increase in proportion to the input current density. When