Spiral-type Magnetic Micromachine Research Articles

Basic Properties of Micropump with Magnetic Micromachine

A micropump with spiral-type magnetic micromachine was fabricated. When a rotating magnetic field was applied, the machine rotated and pumped a surrounding liquid. We experimentally examined the basic properties of this pump. We found that the pressure and the flow rate could be controlled by the rotating frequency, and this pump could work under wide range kinematic viscosity. In addition, we proposed a disposable pump system using the machine. When a plate installed a fluid channel and the machine was set on a stage for generating a rotating magnetic field, the machine worked as the pump.

Design of Spiral-Type Magnetic Micro-machine with Three-Dimensional Analysis of Swimming Properties

Magnetic micro-machines are driven by a magnetic field. They require no power supply cables, no batteries, and no controlling systems on the machine body. In previous studies, we examined the swimming properties of a spiral-type magnetic micro-machine (outer diameter of 0.1 or 1.5 mm) by the experiment and the analysis. This micro-machine is composed of the body of cylinder and the spiral structure. Pulling the thing and the transportation of the thing are given to the application of the micro-machine. At this time, a big load works in the machine. It is necessary to improve thrust to swim against the drag. In this paper, we examined about the influence that machine shape and a spiral shape give to the swimming properties of micro-machine using the analysis. As machine shapes, the having body (Ref-Type) and no (Head-Type) were examined. As a spiral shape, the blade pitch was examined. It was found that the micro-machine of Head-Type suitable for the micro-machine that pulled the thing because the thrust was large. In the case of Ref-Type with the loading on the machine body, the spiral pitch of the maximum thrust was about 1 mm.

スパイラル型磁気マイクロマシンを用いたマイクロポンプ

A micropump with a spiral-type magnetic micromachine was fabricated. The magnetic micromachine was composed of a permanent magnet and a spiral coil. When a rotating magnetic field was applied, the machine rotated and produced a thrust force in a liquid. However, the machine remained still and pumped the liquid at the point of equilibrium between the thrust force and a force created by the field gradient. We experimentally examined the basic properties of the pump, such as the flow rate and pressure. As a result, we found that the latter two properties can be controlled by adjusting the frequency of the rotating magnetic field. The pump was able to produce a maximum pressure of 116 Pa and a flow rate of several ml/min.

Fabrication of micropump with spiral-type magnetic micromachine

The micropump with spiral-type magnetic micromachine was examined by experiment and analysis. In the experiment, when the magnetic field was applied only around the micromachine, the micromachine was fixed and rotated by the magnetic field gradient. This mechanism generated the pressure. The analysis was carried out with three-dimensional analysis. As a result, the analysis result agreed with the experimental one, and the maximum pressure produced by the 1-mm /spl phi/ pump was 70 Pa. Therefore, this micropump could be used for application in very low Reynolds number conditions.

Three-dimensional analysis of swimming properties of a spiral-type magnetic micro-machine

The swimming properties of a spiral-type magnetic micro-machine were analyzed theoretically using 3D finite volume method. The basic equations of incompressible viscous fluid flow were integrated. The flow field around the micro-machine was calculated to estimate the swimming velocity, thrust, drag, and load torque of a spiral-type magnetic micro-machine. Good agreement was obtained between the experimental and theoretical results in a low Reynolds number. Therefore, the 3D analysis method without any fitting parameters was judged to be established.

Fabrication of magnetic micromachine for local hyperthermia

One of the important functions of a micromachine working in the human body is heating for local hyperthermia. A magnetic heating system was attached to a spiral-type magnetic micromachine. This machine could work in a gel and could heat to over 50/spl deg/C by applying a rotational magnetic field and an alternating magnetic field. This machine would be able to move in the internal organs and heat tissues. In addition, the transport capability of the machine was examined on the basis of the shape of the carried elements.

Magnetic micromachines for medical applications

The spiral-type magnetic micromachine can swim in a liquid and in a gel. In addition, this machine has a function of heating. This machine is suitable for local heat treatment in the body. The active bending is obtained by attached tiny magnet at the tip of the guide-wire. This is simple and useful for inserting the catheter to the lung or to the blood tube.

Swimming of magnetic micro-machines under a very wide-range of Reynolds number conditions

A magnetic micro-machine, a minuscule device composed of a cylindrical body with a magnet and spiral blade, swims in liquid under the force of a rotational magnetic field. To obtain a machine capable of swimming through organs and blood vessels for medical applications, it must be designed on a scale below the mm order and retain its swimming capability under highly varied conditions. The swimming properties of a spiral-type magnetic micro-machine were examined under various Reynolds number conditions by altering the kinematic viscosity of the liquid. The machine could swim in liquids with kinematic viscosities ranging from 1.37 to 5/spl times/10/sup 5/ mm/sup 2//s, which translates into a Reynolds number from 430 to 6/spl times/10/sup -7/. The Reynolds number of blood flow is within this range. In addition, the load torque for swimming was studied theoretically and experimentally. The results obtained suggested great promise for the development of a micro-machine that can be put to work inside the human body.

Analysis of Swimming Properties and Design of Spiral-Type Magnetic Micromachine

The swimming properties of spiral-type magnetic micromachines were analyzed theoretically by 2-dimensional finite volume. Good agreement between experimental and theoretical results was obtained. Swimming properties of micromachines depend strongly on the operational environment, including the flow field and machine structure. We analyzed the effect of machine shape on swimming properties. The optimum design of the blade shape was obtained by simulation. Based on optimum design, the micromachine was fabricated by stereolithography. Machine swimming agreed well with results.

1302 医用応用を目的とした磁気マイクロマシンシステムの開発

To develop micro-machines for use in medical application, two kinds of spiral-type magnetic micro-machine, which is driven by an external rotational magnetic field, were fabricated. These machines constructed by permanent magnets and spiral blade. It was demonstrated that changing the direction of the rotation planet of the external rotational field could control swimming direction of the swimming type magnetic micro-machine. The radius of the bend depended on the viscosity of the fluid and on the frequency of the external field. The another magnetic micro-machine could run in a gel and even in bovine meat. Running behavior of the machine depend on a frequency and strength of the external field. In addition, it can be detected where position of the magnetic micro-machine by a magnetic motion capture system.

Effect of machine shape on swimming properties of the spiral-type magnetic micro-machine

The effect of machine shape on the swimming properties of a spiral-type magnetic micro-machine was examined by using a finite volume method. The optimum design of the blade shape was obtained by using the results of the simulation. According to the optimum design, the micro-machine was fabricated by stereolithography. The swimming properties of the machine agreed well with the analyzed results.