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15 Apr 2006

Volume 99, Issue 8, Articles (08xxxx)

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back to top Biomagnetic and Electronic Devices

Low power consumption focusing actuator for a mini video camera

Hsing-Cheng Yu, Tzung-Yuan Lee, Shir-Kuan Lin, Li-Te Kuo, Shyh-Jier Wang, Jau-Jiu Ju, and Der-Ray Huang

J. Appl. Phys. 99, 08R901 (2006); http://dx.doi.org/10.1063/1.2158927 (3 pages) | Cited 6 times

Online Publication Date: 17 April 2006

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A novel low power consumption autofocusing actuator in a mini video camera is constructed in accordance with the result of a systematic design procedure of voice coil motors (VCM). This paper emphasizes the position control of such a VCM. The position feedback signals are provided by a magnetoresistive (MR) encoder. The position estimation algorithm (PEA) is developed to precisely decode the MR signals for the position of the moving part of the VCM. Different postures change the loading of the moving part of the VCM, so that an adaptive model-following control system based on the PEA is proposed to compensate for the loading variation. The experiments verify the fast dynamic performance and high power efficiency of the VCM.
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84.40.Ua Telecommunications: signal transmission and processing; communication satellites

A non-contact energy transferring system for an electric vehicle-charging system based on recycled products

Y. Matsuda, H. Sakamoto, H. Shibuya, and S. Murata

J. Appl. Phys. 99, 08R902 (2006); http://dx.doi.org/10.1063/1.2164408 (3 pages)

Online Publication Date: 18 April 2006

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A non-contact automatic charging system for electric vehicle application is presented. The principle is the same as that of the transformer where the primary and the secondary circuits are separable but coupled with each other without using the hand coupler. In this paper, we present a possibility of removing the core of the secondary coil on the body for reducing the weight of the car. In our experiments, the primary core, which is placed on the earth floor, is made of Mn–Zn ferrite with square shape as 1 m×1 m×10 mm for a large cross-sectional area. The steel floor of the car assists to pass the magnetic flux. An efficiency rate over 90% with the test device of 2 kW is obtained without the conventional secondary core. The leakage inductance is well compensated by a resonance capacitor inserted in the secondary coil. In this experiment, the distance between the primary and the secondary coil is 100 mm and the switching frequency is 100 kHz. In addition, we developed a pavement method for the system. The method utilizes plates made from the waste of expanded polystyrene and rubber mats made from used tire. The plates are set up on the rubber mats and these mats are arranged over the non-contact charging system. The pavements can be replaced easily when the system is exchanged. Therefore, this pavement method is not only practical for the non-contact charging system but is also useful for recycling of resources and reduction of waste matters.
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89.40.Bb Land transportation
82.47.Cb Lead-acid, nickel-metal hydride and other batteries

Magnetic property characterization of magnetite (Fe3O4) nanorod cores for integrated solenoid rf inductors

Jinsook Kim, Weiping Ni, Chungho Lee, Edwin C. Kan, Ian D. Hosein, Yanning Song, and Chekesha Liddell

J. Appl. Phys. 99, 08R903 (2006); http://dx.doi.org/10.1063/1.2165143 (3 pages) | Cited 3 times

Online Publication Date: 20 April 2006

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The on-chip magnetic solenoid inductors with Fe3O4 magnetite nanorod (MN) cores are fabricated and characterized up to 40 GHz. By vibrating-sample magnetometer measurements, the magnetic property of MN as a magnetic core for a solenoid inductor is investigated. In addition, high-frequency characterization with scattering parameter measurements is performed to estimate the high-frequency performance of the solenoid inductors with the MN cores.
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84.32.Hh Inductors and coils; wiring
85.70.Ay Magnetic device characterization, design, and modeling

Magnetic actuator intended for left ventricular assist system

H. Saotome and T. Okada

J. Appl. Phys. 99, 08R904 (2006); http://dx.doi.org/10.1063/1.2170056 (3 pages) | Cited 1 time

Online Publication Date: 21 April 2006

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With the goal of developing an artificial heart, the authors fabricated a prototype pump employing a linear motion magnetic actuator, and carried out performance tests. The actuator is composed of two disk-shaped Nd–Fe–B magnets having a diameter of 80 mm and a thickness of 7 mm. The disks are magnetized in the direction normal to the circular surface, and are formed by semicircular pieces; one semicircle serves as a N pole and the other as a S pole. The magnets face each other in the actuator. One magnet is limited to spin around its axis while the second magnet is limited to move in linear motion along its axis. In this way, the circumferential rotation of one of the magnets produces reciprocating forces on the other magnet, causing it to move back and forth. This coupled action produces a pumping motion. Because the two magnets are magnetically coupled without any mechanical contact, the rotating magnet does not have to be implanted and should be placed outside the body. The rotating magnet is driven by a motor. The motor power is magnetically conveyed, via the rotating magnet, to the implanted linear motion magnet through the skin. The proposed system yields no problems with infection that would otherwise require careful treatment in a system employing a tube penetrating the skin for power transmission. Comparison of the proposed system with another system using a transcutaneous transformer shows that our system has good potential to occupy a smaller space in the body, because it obviates implantation of a secondary part of the transformer, a power supply, and armature windings. The dimensions of the trial pump are designed in accordance with the fluid mechanical specifications of a human left ventricle, by computing magnetic fields that provide the magnetic forces on the magnets. The output power of the trial pump, 1.0 W at 87 beats/min, is experimentally obtained under the pressure and flow conditions of water, 100 mm Hg and 4.5 l/min.
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87.80.-y Biophysical techniques (research methods)
85.70.-w Magnetic devices
87.19.U- Hemodynamics
87.19.Wx Pneumodyamics, respiration
47.63.Cb Blood flow in cardiovascular system
84.70.+p High-current and high-voltage technology: power systems; power transmission lines and cables

A method to obtain uniform magnetic-field energy density gradient distribution using discrete pole pieces for a microelectromechanical-system-based magnetic cell separator

Pulak Nath, Lee R. Moore, Maciej Zborowski, Shuvo Roy, and Aaron Fleischman

J. Appl. Phys. 99, 08R905 (2006); http://dx.doi.org/10.1063/1.2171936 (3 pages)

Online Publication Date: 24 April 2006

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A spatially uniform magnetic energy density gradient (∇B2) distribution offers a controlled environment to separate magnetically tagged cells or biomolecules based on their magnetophoretic mobility [ L. R. Moore et al., J. Biochem. Biophys. Methods 37, 11 (1998) ]. A design to obtain a uniform ∇B2 distribution for a microelectromechanical-systems-based magnetic cell separator was developed. The design consists of an external magnetic circuit and a microfabricated channel (biochip) with embedded discrete pole pieces on the channel walls. The two-dimensional and three-dimensional magnetostatic simulation softwares utilizing boundary element methods were used to optimize the positions and the dimensions of the discrete pole pieces, as well as the external magnetic circuit—the combination of which would generate a uniform ∇B2 profile over the channel cross section. It was found that the discrete pole pieces required specific magnetic properties (saturation magnetization constant >1.55 T) to affect the overall ∇B2 distribution. Investigating different positions of the discrete pole pieces inside the external magnetic field indicated that the proposed design could generate uniform ∇B2 distribution with ±100 μm displacements along the height/width and ±1° inclination from the optimum position.
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87.80.-y Biophysical techniques (research methods)
87.17.Jj Cell locomotion, chemotaxis
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
07.10.Cm Micromechanical devices and systems
02.60.Lj Ordinary and partial differential equations; boundary value problems

Magnetic cell manipulation utilizing magnetic particles and diamagnetic collagen fibers

M. Iwasaka, T. Kurakane, T. Kimura, F. Kimura, and S. Ueno

J. Appl. Phys. 99, 08R906 (2006); http://dx.doi.org/10.1063/1.2175957 (3 pages)

Online Publication Date: 26 April 2006

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This paper reports a method of controlling the orientation of adherent fibroblastic cells (osteoblasts) by utilizing a ferromagnetic particle chain and a diamagnetic collagen under exposure to magnetic fields. A cell culture medium with cells and magnetic particles (γ-Fe2O3) was mixed with a collagen solution and incubated for 24 h. During the first 3 h of incubation, the medium in the cell culture dish was exposed to magnetic fields of up to 8 T. The exposure caused the aggregation of magnetic particles (MPs), which formed chains in parallel with the magnetic field and at the same time oriented the polymerized collagen fibers perpendicular to the magnetic field. A lattice pattern of MP chains and collagen fibers was observed on the bottom of the culture flask. After 24 h of incubation, the spindlelike cells had become oriented in parallel with the MP chains or the collagen fibers. The results indicate the possibility of a technique of cellular manipulation with MP-collagen hybrid that could be used to control cellular orientation.
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87.80.-y Biophysical techniques (research methods)
87.17.-d Cell processes
87.14.E- Proteins

Pattern storage and recognition using ferrofluids

Shuai Ban and V. Korenivski

J. Appl. Phys. 99, 08R907 (2006); http://dx.doi.org/10.1063/1.2176895 (3 pages) | Cited 3 times

Online Publication Date: 26 April 2006

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An implementation of an associative memory based on a ferromagnetic nanocolloid is proposed. The design contains inductive input and output units for training the ferrofluid as well as sensors incorporated into the output units for performing recall. Using Monte Carlo simulations of the system we demonstrate the possibility of creating nanoparticle configurations that can serve to associate input/output pattern pairs.
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85.70.Li Other magnetic recording and storage devices (including tapes, disks, and drums)
84.30.Sk Pulse and digital circuits

Improvement of pulse diagnostic apparatus with array sensor of magnetic tunneling junctions

S. W. Kim, D. G. Hwang, Y. K. Choi, H. S. Lee, D. H. Park, S. S. Lee, G. W. Kim, S. G. Lee, and S. J. Lee

J. Appl. Phys. 99, 08R908 (2006); http://dx.doi.org/10.1063/1.2177388 (3 pages) | Cited 1 time

Online Publication Date: 26 April 2006

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To obtain the spatial feature of arterial pulse, a spatial pulse diagnostic apparatus was designed using a two-dimensional magnetoresistive sensor array. The magnetic-field distribution for the magnet array was simulated using the finite-element method. The field distribution of parallel magnet arrays was observed to be more sensitive and uniform than that of the perpendicular ones. Moreover, the spatial displacements of the magnet array coincided with the output signal of the magnetic tunneling junction sensor array.
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87.80.-y Biophysical techniques (research methods)
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
07.55.-w Magnetic instruments and components
02.70.Dh Finite-element and Galerkin methods
85.70.Kh Magnetic thin film devices: magnetic heads (magnetoresistive, inductive, etc.); domain-motion devices, etc.

Improvement of communication area for implantable signal transmission system with ferrite chip core

Tetsuya Takura, Tatsuo Somekawa, Fumihiro Sato, Hidetoshi Matsuki, and Tadakuni Sato

J. Appl. Phys. 99, 08R909 (2006); http://dx.doi.org/10.1063/1.2177424 (3 pages) | Cited 2 times

Online Publication Date: 3 May 2006

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Transcutaneous power and signal transmission system are useful for artificial hearts. The signal transmission system is important to control the implanted device and to monitor the inside condition. They do not have lines penetrating through the skin. The signal transmission coils are set on the power transmission coils. We have proposed integrated power and signal transmission system utilizing eight-figure coils. Using the signal transmission coil pairs we have proposed, we studied through measurements and experiments the communication area for implantable signal transmission system with a ferrite chip core.
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87.80.-y Biophysical techniques (research methods)
84.70.+p High-current and high-voltage technology: power systems; power transmission lines and cables
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