Localization of Amorphous Wire Using

The Barkhausen EffectMatthias Ziegler

3/15/2001

Outline

• What are we trying to accomplish?• Why do we need this localization?• How are we going to use this?• What is the Barkhausen Effect?• What is the effect on Amorphous Wire?

What Are We Trying to Accomplish?

• Localization of a point within a body, using the smallest possible wire

• We want to localize at least < 1mm• No radiation needed• Minimal cost

Why Do We Need This?

• Automatic alignment of treatment machines with tumor locations in radiation oncology

• Establishing location and direction of probe tip in colonoscopy procedures

• Use of handheld device to identify an inserted catheter tip

• Prostate localization for computer-aided seed implants in brachytherapy

How Will We Accomplish This?

• Using a magnetic field and amorphous wire we can implement the Barkhausen Effect.

• This effect can be used then triangulate the position of the wire

What is the Barkhausen Effect?

• 1919- Heinrich Barkhausen discovers new magnetic properties– When placed in a magnetic field,

ferromagnetic wire will become magnetized in small distinct jumps that can be easily found and recorded

Uses of the Barkhausen Effect

• Key Element of Read-Write Hard Drives– IBM– Jerry Cuomo

• Anti-Theft Devices– IBM– When product with device passes through

magnetic field the magnetic spike is detected.

References

• Large Barkhausen And Matteucci Effects in FeCoSiB, FeCrSiB, and FeNiSiB Amorphous Wires. By K. Mohri, F.B. Humphrey, K. Kawashima, K. Kimura, and M. Mizutani. IEEE Trans. on Magn., Vol. 26, No. 5, Sept 1990

• Distance Sensors Utilizing Large Barkhausen Effect Excited By Wire Current Pulse Train In Twisted Amorphous Magnetostrictive Wires. By I M. Mizutani. IEEE Trans. Magn. Vol 29, No 6, Nov 1993

Description of Wire

• Wire is made by a rotating wheel melt-quench process

• Usually comprises of an alloy of FeSiB or FeCoSiB

• Size of wire can be as small as 50 microns in diameter and 2cm long

• Wire can be bent

Implementation By Paper

• These papers use three different methods– Excitation from a wire used to create the

Barkhausen effect in the amorphous wire– Magnetic Field from a longitudinal source– Magnetic Field from a perpendicular source

Example of Barkhausen Effect(From Wire Current Paper)

• Done by excitation from a wire current• Here the wire takes 7 jumps to magnetize• Diameter of wire = 50 µm

•Distance Sensors Utilizing Large Barkhausen Effect Excited By Wire Current. By I M. Mizutani. IEEE Trans. Magn. Vol 29, No 6, Nov 1993

How Wire Reacts Within a Magnetic Field

• In a static magnetic field the wire has a magnetic core

• A 180 degree reversal in direction of the core occurs when the applied ac field reverses polarity and reaches a value of field of .5-1 Oersteds

Magnetic Field From Wire

Magnetic Source

How We Will Implement the Field

Amorphous Wires

Pick-up Sensors

Magnetic Field Source

Barkhausen Effect on Amorphous Wire With

Longitudinal Magnetic Field• Using a magnetic

field the wire will become magnetic in 1 jump, causing a spike in the magnetic sin wav

• The spikes occur when the sinusoidal field reverses direction

Wire Properties

• The location of the spike will change with wires of different diameters

• The amplitude of the spike will change on distance

• Only ferromagnetic materials will disrupt the field

Sensors

• Each sensor is a simple coil of wire, which that is about 2-3 cm in diameter

• These sensors can easily be read by an oscilloscope

• They can also be directly sent to a computer

Conclusions (papers)

• Using a wire current to excite the field, it is possible to create sensors that will detect the Barkhausen effect in amorphous wire

• By creating a large magnetic field we can create a single “spike”.

Conclusions (Mine)• Using this magnetic field we will be able to set

up a system that will be able to sense the single spike created by the amorphous wire with high accuracy.

• This system will be able to be used in the medical field to determine locations of needed points.

• System would be minimally invasive and highly decrease the amount of radiation needed for a patient.