Passive and wireless in-vivo acoustic wave flow sensor

• US 20050240110A1
• Filed: 04/21/2004
• Published: 10/27/2005
• Est. Priority Date: 04/21/2004
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Liu, James Z., Alderman, Richard A.
• Granted Patent: US 7,399,280 B2
• Time in Patent Office: Days
• US Class Current: 600/505
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/411 Detecting or monitoring allergy or intolerance reactions to an allergenic agent or substance
• CPC Class Codes: A61B 8/06 Measuring blood flow measuring volume flow in general G01F, e.g. G01F1/66, G01F1/72; measuring speed of fluids in general G01P5/00
• CPC Class Codes: A61B 8/12 in body cavities or body tracts, e.g. by using catheters catheters per se A61M25/00
• CPC Class Codes: A61B 8/4472 Wireless probes
• CPC Class Codes: G01F 1/6882 making use of temperature dependence of acoustic properties, e.g. propagation speed of surface acoustic waves

Abstract

A wireless surface wave flow sensor can be utilized for monitoring the flow of fluid. Such a surface wave flow sensor can be configured to include one or more interdigital transducers and a self-heating heater formed upon a piezoelectric substrate. The interdigital transducer(s) can be selected to convert electrical signals to surface waves thereof. An antenna can also be connected to the surface wave device, wherein the antenna can receive one or more signals, which excites the acoustic device to produce a frequency output associated with the flow of the fluid for analysis thereof.

Claims

1. A fluid flow sensing system, comprising:

a surface acoustic wave flow sensor for monitoring a flow of fluid through a compartment formed from a plurality of walls, wherein said surface acoustic wave flow sensor comprises at least one interdigital transducer and a self-heating heater formed upon a piezoelectric substrate, wherein said interdigital transducer is selected to introduce negligible electrical coupling to surface waves thereof; and

an antenna connected to said at least one interdigital transducer, wherein said antenna receives at least one signal, which excites said at least one interdigital transducer to produce a frequency output associated with said flow of said fluid for analysis thereof.

2. The system of claim 1 further comprising a transmitter and receiver unit for transmitting said at least one signal to said antenna for exciting said at least one interdigital transducer to produce said at least one frequency output associated with said flow of said fluid for analysis thereof.

3. The system of claim 2 wherein said fluid comprises blood and wherein said surface acoustic wave flow sensor and said antenna thereof are implantable within a human body for monitoring said blood and wherein said transmitter and receiver unit is located outside of said human body.

4. The system of claim 1 wherein said at least one frequency output comprise at least one of the following types of data:

flexural plate mode (FMP) data, acoustic plate mode data;

shear-horizontal acoustic plate mode (SH-APM) data;

amplitude plate mode (APM) data;

thickness shear mode (TSM) data;

surface acoustic wave mode (SAW), and bulk acoustic wave mode (BAW) data;

torsional mode data;

love wave data;

leaky surface acoustic wave mode (LSAW) data;

pseudo surface acoustic wave mode (PSAW) data;

transverse mode data, surface-skimming mode data;

surface transverse mode data;

harmonic mode data; and

overtone mode data.

5. The system of claim 1 wherein said at least one interdigital transducer comprises electrode materials selected from among a group of materials comprising at least one of the following metals:

Al, Pt, Au, Rh, Ir, Cu, Ti, W, Cr, or Ni.

6. The system of claim 1 wherein said at least one interdigital transducer comprises electrode materials selected from among a group of materials comprising alloys.

7. The system of claim 1 wherein said at least one interdigital transducer comprises electrode materials selected from among a group of materials comprising metal-nonmetal compounds.

18. The method of claim 1 wherein said at least one interdigital transducer comprise electrode materials selected from among a group of materials comprising at least one of the following metals:

Al, Pt, Au, Rh, Ir, Cu, Ti, W, Cr, or Ni.

19. The method of claim 1 wherein said at least one interdigital transducer comprises electrode materials selected from among a group of materials comprising alloys.

20. The method of claim 1 wherein said at least one interdigital transducer comprises electrode materials selected from among a group of materials comprising metal-nonmetal compounds.

8. A fluid flow sensing system, comprising:

a surface acoustic wave flow sensor for monitoring a flow of fluid, wherein said surface acoustic wave flow sensor comprises at least one interdigital transducer and a self-heating heater formed upon a piezoelectric substrate, wherein said at least one interdigital transducer is selected to introduce negligible electrical coupling to surface waves thereof;

an antenna connected to said at least one interdigital transducer, wherein said antenna receives at least one signal, which excites said at least one interdigital transducer to produce a frequency output associated with said flow of said fluid for analysis thereof, wherein said fluid comprises blood and wherein said surface acoustic wave flow sensor and said antenna are implantable within a human body for monitoring said blood; and

a transmitter and receiver unit for transmitting said at least one signal to said antenna for exciting said at least one interdigital transducer to produce said at least one frequency output associated with said flow of said fluid for analysis thereof, wherein said transmitter and receiver unit is located outside of said human body.

9. The system of claim 8 wherein said at least one interdigital transducer comprise electrode materials selected from among a group of materials comprising at least one of the following metals:

Al, Pt, Au, Rh, Ir, Cu, Ti, W, Cr, or Ni.

10. The system of claim 8 wherein said at least one interdigital transducer comprises electrode materials selected from among a group of materials comprising alloys.

11. The system of claim 8 wherein said at least one interdigital transducer comprises electrode materials selected from among a group of materials comprising metal-nonmetal compounds.

12. The system of claim 8 wherein said at least one interdigital transducer comprises at least one SAWu component and at least one SAWd component.

13. The system of claim 8 wherein said at least one frequency output comprise at least one of the following types of data:

flexural plate mode (FMP) data, acoustic plate mode data;

shear-horizontal acoustic plate mode (SH-APM) data;

amplitude plate mode (APM) data;

thickness shear mode (TSM) data;

surface acoustic wave mode (SAW), and bulk acoustic wave mode (BAW) data;

torsional mode data;

love wave data;

leaky surface acoustic wave mode (LSAW) data;

pseudo surface acoustic wave mode (PSAW) data;

transverse mode data, surface-skimming mode data;

surface transverse mode data;

harmonic mode data; and

overtone mode data.

14. A fluid flow sensing method, comprising the steps of:

providing a surface acoustic wave flow sensor for monitoring a flow of fluid, wherein said surface wave flow sensor comprises at least one interdigital transducer and an acoustic coating formed upon a piezoelectric substrate, wherein said at least one interdigital transducer is selected to introduce negligible electrical coupling to surface waves thereof; and

connecting an antenna to surface acoustic wave device, wherein said antenna receives at least one signal, which excites said at least one interdigital transducer to produce a frequency output associated with said flow of said fluid for analysis thereof.

15. The method of claim 14 further comprising the step of providing at a transmitter and receiver unit for transmitting said at least one signal to said antenna for exciting said at least one interdigital transducer to produce said at least one frequency output associated with said flow of said fluid for analysis thereof.

16. The method of claim 14 wherein said fluid comprises blood and wherein said surface wave flow sensor and said antenna are implantable within a human body for monitoring said blood.

17. The method of claim 14 wherein said at least one frequency output comprise at least one of the following types of data:

flexural plate mode (FMP) data, acoustic plate mode data;

shear-horizontal acoustic plate mode (SH-APM) data;

amplitude plate mode (APM) data;

thickness shear mode (TSM) data;

surface acoustic wave mode (SAW), and bulk acoustic wave mode (BAW) data;

torsional mode data;

love wave data;

leaky surface acoustic wave mode (LSAW) data;

pseudo surface acoustic wave mode (PSAW) data;

transverse mode data, surface-skimming mode data;

surface transverse mode data;

harmonic mode data; and

overtone mode data.