Magnetic shielding garment for electro-biologic measurements

DETAILED DESCRIPTION This invention encompasses a garment for electromagnetically shielding a patient.
The shielding allows sensitive medical measurements to be made with reduced levels of interference from electromagnetic signals.
Electromagnetic interference is commonly present in laboratories, hospitals and industrialized areas.
All of these locations are places in which one may desire to make sensitive medical measurements on a patient.
Alternating current power lines are generally the source of the magnetic interference.
The typical power line interference is comprised of a fundamental frequency of 50 or 60 Hertz, and the first few harmonics of the fundamental.
Other sources of strong interfering electromagnetic fields are motors, CRT monitors and power supplies.
As shown in FIG.
1, the garment 100 wraps around the patient wearing it, and it should be made out of a flexible material.
Continual flexing of most shielding materials will reduce their permeability.
An amorphous alloy is chosen for this invention because of its tolerance to mechanical flexing and stressing.
Amorphous alloys also have excellent magnetic shielding properties.
Amorphous alloys have a high magnetic permeability of up to 100,000 .
mu.
z at frequencies of less than 1000 hertz.
They are light weight, have acceptable handling properties and offer construction workability.
Amorphous alloys also have high mechanical elasticity.
Therefore, if the material is deformed by a stress imposed during handling, the shape is restored when the stress is released.
One aspect of this invention includes an interleaved weave of amorphous alloy strips 210 as shown in FIG.
2.
The strips 210 are woven together to form a large rectangular sheet 200.
The final configuration can be composed of many sheets 200 layered on top of each other.
The amount of shielding will be greater as the number of sheets 200 is increased.
Experimentally, it has been found that each sheet 200 of fabric made from 0.
0008" Metglas.
RTM.
provides about 4/3 dB of magnetic field strength attenuation at a magnetic field frequency of between 60-300 Hz