Method of measuring properties of an object with acoustically induced electromagnetic waves

Patent metadata

Field	Value
Publication number	US-9901281-B2
Application number	US-201213445786-A
Country	US
Kind code	B2
Filing date	Apr 12, 2012
Priority date	Nov 9, 2005
Publication date	Feb 27, 2018
Grant date	Feb 27, 2018

Abstract

A measuring method and apparatus in which a measurable object ( 23 ) is irradiated with acoustic waves to measure a change in property value of charged particles in the object from electromagnetic waves induced thereby. A part ( 2 ) of the measurable object irradiated with an acoustic focused beam ( 1 ) is in a charge distribution state in which positive charged particles ( 3 ) are greater in number in the part ( 2 ) where electromagnetic waves induced by positive charged particles ( 3 ) are not canceled by those induced by negative charged particles ( 4 ) and where net electromagnetic waves ( 6 ) are induced. Since a change in concentration of positive charged particles ( 3 ) and/or negative charged particles ( 4 ) changes the intensity of electromagnetic waves ( 6 ), it is possible to know such a change in concentration of the charged particles from a change in intensity of electromagnetic waves ( 6 ).

First claim

What is claimed is:

1. A method of measuring a property of an object with acoustically induced electromagnetic waves, the method comprising:
emitting, from an emission source, an acoustic wave pulse towards the object that is placed at a prescribed distance from the emission source, wherein the emission source generates, upon emission of the acoustic wave pulse, electromagnetic noises which are produced by the emission source and which last after completing the emission of the acoustic wave pulse, and wherein the prescribed distance is such that a time period for the acoustic wave pulse to travel over the prescribed distance is longer than duration of the electromagnetic noises which are in form of electromagnetic waves;
receiving electromagnetic waves including induced electromagnetic waves which are induced from the object in response to the acoustic wave pulse, and the electromagnetic noises;
obtaining the induced electromagnetic waves by referring to the received electromagnetic waves only at a predetermined period which is determined by the prescribed distance and regarding the referred electromagnetic waves as the induced electromagnetic waves, whereby the induced electromagnetic waves and electromagnetic noises are separated in time from each other; and
processing the induced electromagnetic waves induced from the object to determine any one of properties of the object, including its electrical, magnetic and electromagnetic/mechanical properties, from any one or a combination of strength, phase and frequency characteristics of the induced electromagnetic waves.

2. The method of measuring a property of an object with acoustically induced electromagnetic waves as set forth in claim 1 , wherein the electric property of the object includes a change or changes in one or more of property values for electric field, dielectric constant, spatial gradient of electric field and spatial gradient of dielectric constant and for concentration, mass, size, shape and number of charges of charged particles which the object possesses and for interaction with a medium surrounding the charged particles.

3. The method of measuring a property of an object with acoustically induced electromagnetic waves as set forth in claim 1 , wherein magnetic property of the object includes a property value for magnetization due to electron spin or nuclear spin in the object or for acousto-magnetic resonance attributable to the electron spin or nuclear spin in the object.

4. The method of measuring a property of an object with acoustically induced electromagnetic waves as set forth in claim 1 , wherein the electromagnetic/mechanical properties of the object includes a piezoelectric property or magnetostriction property of the object.

5. The method of measuring a property of an object with acoustically induced electromagnetic waves as set forth in claim 1 , wherein by measuring time dependence of their intensity detected subsequent to irradiation with the acoustic wave pulse, a relaxation characteristic of a property value for charged particles which the object possesses is measured.

6. The method of measuring a property of an object with acoustically induced electromagnetic waves as set forth in claim 1 , wherein the acoustic wave pulse is emitted in a plurality at a fixed frequency in a narrow band and the induced electromagnetic waves are measured by heterodyne or phase detection of the induced electromagnetic waves induced from the object with the fixed frequency of the acoustic wave-pulse as a reference signal and by the heterodyne or phase detection of a signal resulting from the detection with the fixed frequency of the acoustic wave pulse.

7. The method of measuring a property of an object with acoustically induced electromagnetic waves as set forth in claim 6 , wherein from phase information of the phase detection, it is determined whether the induced electromagnetic waves originate from positively charged particles or negatively charged particles possessed by the object.

8. The method of measuring a property of an object with acoustically induced electromagnetic waves as set forth in any one of claims 1 , 5 , and 6 , wherein the object is irradiated with acoustic waves by focusing acoustic waves from a plurality of sources on a desired small part of the object and the induced electromagnetic waves induced at the small part are measured by an antenna or coil that surrounds the object, whereby acoustic waves are focused on a desired part from a desired direction and the induced electromagnetic waves radiated from desired positions towards a desired direction are measured while their radiation bearing distribution is determined.

9. The method of measuring a property of an object with acoustically induced electromagnetic waves as set forth in claim 8 , wherein focusing acoustic waves is scanned over a two-dimensional surface or three-dimensional volume of the object and an intensity of the induced electromagnetic waves at each scanning position is measured by the antenna or coil that surrounds the object to determine a two-dimensional or three-dimensional distribution of changes in a property value of charged particles of the object.

10. The method of measuring a property of an object with acoustically induced electromagnetic waves as set forth in claim 1 or claim 5 , wherein the acoustic wave pulse is emitted in a plurality in the form of broadband ultrashort pulses and the frequency of the induced electromagnetic waves is measured, whereby, information on depthwise position of charged particles from which the electromagnetic waves are induced is obtained from the measured frequency of the induced electromagnetic waves.

11. The method of measuring a property of an object with acoustically induced electromagnetic waves as set forth in any one of claims 1 , 2 , 5 , and 6 , wherein the object is a nervous tissue representative of a brain or a muscle tissue of a living body, and a charge distribution formed when neuron or muscle tissue is activated is measured as changes in property value of charged particles to identify a site of the activated neuron or muscle tissue.

12. The method of measuring a property of an object with acoustically induced electromagnetic waves as set forth in any one of claims 1 , 2 , 5 , and 6 , wherein the object is of any one of materials selected from the group which consists of colloidal solution, liquid crystal, solid electrolyte, ionic crystal, semiconductor, dielectric, metal, magnetic material and magnetic fluid or a composite material thereof or a structure or a functional device composed of such a material, in which a change in property value of charged particles is measured.

13. The method of measuring a property of an object with acoustically induced electromagnetic waves as set forth in claim 1 , wherein in the step of receiving electromagnetic waves, the induced electromagnetic waves are those in near-field.

14. A method of measuring a property of an object with acoustically induced electromagnetic waves, the method comprising:
emitting, from an acoustic wave pulse emission source, an acoustic wave pulse towards the object wherein a prescribed distance between the acoustic wave pulse emission source and the object are set so that a period during which the acoustic wave pulse emitted from the acoustic wave pulse emission source reaches the object is longer than a duration of electromagnetic noises produced by the acoustic wave pulse emission source;
receiving electromagnetic waves induced from the object, wherein the induced electromagnetic waves and electromagnetic noises are separated in time from each other; and
determining any one

Assignees

• Ikushima Kenji
• Komiyama Susumu
• Japan Science & Tech Agency

Inventors

• Ikushima Kenji
• Komiyama Susumu

Classifications

• A61B2562/0223

  Magnetic field sensors · CPC title

• A61B5/7235

  Details of waveform analysis (detecting specific parameters of the electrocardiograph cycle A61B5/349) · CPC title

• A61B5/7225

  Details of analogue processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation (input circuits for detecting, measuring, or recording bioelectric or biomagnetic signals A61B5/30; specific diagnostic methods using bioelectric or biomagnetic signals A61B5/316) · CPC title

• A61B5/05 Primary

  Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves (measuring movement of the entire body or parts thereof A61B5/11; detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof A61B5/24) · CPC title

• G01R33/1269

  of molecules labeled with magnetic beads (magnetic particles for bio assay G01N33/54326) · CPC title