DEVICES FOR ANALYSIS OF A FLUID

Abstract

An ultrasonic transducer is described, including a piezoelectric element, a fluid medium contact layer, a matching layer between the piezoelectric element and the fluid medium contact layer, and a backing layer. Ultrasound sensor devices utilising the ultrasonic transducer are also described, for use in systems for analysing a fluid such as milk.

Claims

1. An ultrasonic transducer including: a piezoelectric element, wherein the piezoelectric element has an acoustic impedance of between 15 to 22 MRayls; a fluid medium contact layer, wherein the fluid medium contact layer is a polymer layer; a matching layer between the piezoelectric element and the fluid medium contact layer, wherein the matching layer has an acoustic impedance of between 4 to 10 MRayls; and a backing layer, wherein the backing layer has an acoustic impedance of between 15 to 20 MRayls.

2. The ultrasonic transducer of claim 1, wherein the piezoelectric element is a lead metaniobate piezoelectric element.

3. The ultrasonic transducer of claim 1, wherein the polymer layer is polysulfone.

4. The ultrasonic transducer of claim 1, wherein the thickness of the fluid medium contact layer is configured to delay reflections of an acoustic signal from an interface between the fluid medium contact layer and a fluid in contact with the fluid medium contact layer by a predetermined number of wavelengths, or part wavelengths, of the acoustic signal.

5. The ultrasonic transducer of claim 4, wherein the thickness of the fluid medium contact layer is greater than two wavelengths of the acoustic signal.

6. The ultrasonic transducer of claim 1, wherein the matching layer is a hydrocarbon ceramic laminate layer.

7. The ultrasonic transducer of claim 1, wherein the matching layer has an acoustic impedance of between 5 to 8 MRayls.

8. The ultrasonic transducer of claim 1, wherein the thickness of the matching layer is configured to provide quarter wave matching with the acoustic signal.

9. The ultrasonic transducer of claim 8, wherein the thickness of the matching layer is between 0.2 to 0.3 wavelengths of the acoustic signal at the centre frequency of the ultrasonic transducer.

10. The ultrasonic transducer of claim 1, wherein the matching layer is a circuit board layer.

11. The ultrasonic transducer of claim 10, wherein the circuit board layer provides electrical connections to the piezoelectric element.

12. The ultrasonic transducer of claim 1, wherein the backing layer has an acoustic impedance substantially that of the piezoelectric element.

13. The ultrasonic transducer of claim 1, wherein at least one of the following is true: the backing layer is a tungsten composite layer; the tungsten composite of the tungsten composite layer includes first tungsten particles of a first size, and second tungsten particles of a second size; the first tungsten particles are a granulated tungsten powder, and the second tungsten particles are a fine tungsten powder; a ratio of granulated tungsten powder to fine tungsten powder in the tungsten composite is about 56:7; the backing layer comprises a graduation in density of the first tungsten particles and the second tungsten particles; and any combination thereof.

14. (canceled)

15. (canceled)

16. (canceled)

17. (canceled)

18. The ultrasonic transducer of claim 1, wherein the ultrasonic transducer has a centre frequency of one of: between 1 to 10 MHz, between 3 to 5 MHz, 3.5 to 4 MHz, and about 3.75 MHz.

19. (canceled)

20. (canceled)

21. (canceled)

22. The ultrasonic transducer of claim 1, wherein the ultrasonic transducer has a −6 dB percentage bandwidth greater than 60%.

23. (canceled)

24. The ultrasonic transducer of claim 1, wherein the −6 dB bandwidth is between 2 to 3 MHz.

25. The ultrasonic transducer of claim 1, wherein at least one of the following is true: the ultrasonic transducer further includes a housing having a main body, wherein a portion of the main body provides the fluid medium contact layer; the main body includes a projection through which an acoustic pathway of the ultrasonic transducer passes; the ultrasonic transducer further includes a piezoelectric assembly, the piezoelectric assembly including the piezoelectric element and the matching layer; the piezoelectric assembly includes an element holder having an aperture in which the piezoelectric element is located; wherein the element holder is made of a circuit board material; the matching layer spans the aperture of the element holder; the piezoelectric assembly includes an electrical contact on an opposing side of the piezoelectric element from the matching layer; the main body includes a slotted portion configured to receive the piezoelectric assembly, wherein the ultrasonic transducer further includes a cap configured to be secured to the main body to hold the piezoelectric assembly in place within the slotted portion; and any combination thereof.

26. (canceled)

27. (canceled)

28. (canceled)

29. (canceled)

30. (canceled)

31. (canceled)

32. (canceled)

33. (canceled)

34. (canceled)

35. (canceled)

36. (canceled)

37. (canceled)

38. (canceled)

39. (canceled)

40. (canceled)

41. (canceled)

42. (canceled)

43. (canceled)

44. A system for analysing a fluid, including: a ultrasound sensor device comprising an ultrasonic transducer as claimed in claim 1. a sample delivery device configured to deliver a sample of fluid from a fluid carrying and/or storing system to the ultrasound sensor device; and at least one processor configured to determine a characteristic of the sample of fluid based at least in part on a signal output from the ultrasound sensor device.

45. The system of claim 44, wherein the fluid is one of: a liquid, a solution including a liquid, and milk.

46. (canceled)

47. An ultrasound sensor device, including: an elongate hollow body configured to receive a fluid to be analysed; a first ultrasound transducer, provided at a first end of the hollow body, wherein the first ultrasound transducer includes: a piezoelectric element, wherein the piezoelectric element has an acoustic impedance of between 15 to 22 MRayls; a fluid medium contact layer, wherein the fluid medium contact layer is a polymer layer; a matching layer between the piezoelectric element and the fluid medium contact layer, wherein the matching layer has an acoustic impedance of between 4 to 10 MRayls; and a backing layer, wherein the backing layer has an acoustic impedance of between 15 to 20 MRayls.

48. The ultrasound sensor device of claim 47, further including a second ultrasound transducer of the same configuration as the first ultrasound transducer, wherein the second ultrasound transducer is provided at a second end of the hollow body and facing the first ultrasound transducer.

49. The ultrasound sensor device of claim 48, wherein a length of the respective fluid medium contact layers of the first ultrasound transducer and the second ultrasound transducer is less than 15% of the overall path length.

50. The ultrasound sensor device of claim 48, wherein a path length between the respective piezoelectric elements of the first ultrasound transducer and the second ultrasound transducer is one of: greater than about 25 mm, between 25 mm to 100 mm, and about 70 mm.

51. The ultrasound sensor device of claim 47, wherein the hollow body is made of a metal.

52. The ultrasound sensor device of claim 47, wherein the hollow body comprises an acoustically reflective surface, wherein the first ultrasound transducer faces the acoustically reflective surface.

53. The ultrasound sensor device of claim 52, wherein a total return path length between the piezoelectric element of the first ultrasound transducer and the acoustically reflective surface is one of: greater than about 25 mm, between 25 mm to 100 mm, and about 70 mm.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0078] Further aspects of the present invention will become apparent from the following description which is given by way of example only and with reference to the accompanying drawings in which:

[0079] FIG. 1 is a schematic diagram of an exemplary livestock management system in which an aspect of the present disclosure may be implemented;

[0080] FIG. 2 is a schematic diagram of an exemplary on-line sensor according to one aspect of the present disclosure;

[0081] FIG. 3A is a top view of an exemplary ultrasound sensor device according to one aspect of the present disclosure;

[0082] FIG. 3B is a side cross-section view of the ultrasound sensor device;

[0083] FIG. 4A is a perspective assembled view of an exemplary ultrasound transducer according to one aspect of the present disclosure;

[0084] FIG. 4B is a perspective exploded view of the ultrasound transducer;

[0085] FIG. 4C is a side cross-sectional view of the ultrasound transducer;

[0086] FIG. 5 is a perspective view of an exemplary piezoelectric assembly of the ultrasound transducer according to one aspect of the present disclosure, and

[0087] FIG. 6 is a graph of the frequency response of an exemplary ultrasound transducer according to one aspect of the present disclosure.

DETAILED DESCRIPTION

[0088] Exemplary embodiments are discussed herein in the context of analysis of milk. However, it should be appreciated that principles of the disclosure discussed herein may be applied to the analysis of other fluids.

[0089] FIG. 1 illustrates a livestock management system 100, within which a local hardware platform 102 manages the collection and transmission of data relating to operation of a milking facility. The hardware platform 102 has a processor 104, memory 106, and other components typically present in such computing devices. In the exemplary embodiment illustrated the memory 106 stores information accessible by processor 104, the information including instructions 108 that may be executed by the processor 104 and data 110 that may be retrieved, manipulated or stored by the processor 104. The memory 106 may be of any suitable means known in the art, capable of storing information in a manner accessible by the processor 104, including a computer-readable medium, or other medium that stores data that may be read with the aid of an electronic device. The processor 104 may be any suitable device known to a person skilled in the art. Although the processor 104 and memory 106 are illustrated as being within a single unit, it should be appreciated that this is not intended to be limiting, and that the functionality of each as herein described may be performed by multiple processors and memories, that may or may not be remote from each other. The instructions 108 may include any set of instructions suitable for execution by the processor 104. For example, the instructions 108 may be stored as computer code on the computer-readable medium. The instructions may be stored in any suitable computer language or format. Data 110 may be retrieved, stored or modified by processor 104 in accordance with the instructions 108. The data 110 may also be formatted in any suitable computer readable format. Again, while the data is illustrated as being contained at a single location, it should be appreciated that this is not intended to be limiting—the data may be stored in multiple memories or locations. The data 110 may also include a record 112 of control routines for aspects of the system 100.

[0090] The hardware platform 102 may communicate with various devices associated with the milking facility, for example: in-line sensors 114a to 114n associated with individual milking clusters within the milking facility, and sample sensors in the form of on-line sensors 116a to 116n associated with the individual milking clusters or milk jars collecting milk from same.

[0091] Animal identification devices 118a to 118n are provided for determining an animal identification (“animal ID”) of individual animals entering, or within, the milking facility. More particularly, the animal identification devices 118a to 118n may be used to associated an animal ID with each of the milking clusters associated with the in-line sensors 114a to 114n and on-line sensors 116a to 116n, such that the sensor data may be attributed to the individual animals. A variety of methodologies are known for the determination of an animal ID—for example a radio frequency identification (“RFID”) reader configured to read a RFID tag carried by the animal. In an alternative embodiment, or in conjunction with the animal identification devices 118a to 118n, a user may manually enter (or correct) animal IDs via a user device—examples of which are discussed below.

[0092] The hardware platform 102 may also communicate with user devices, such as touchscreen 120 located within the milking facility for monitoring operation of the system, and a local workstation 122. The hardware platform 102 may also communicate over a network 124 with one or more server devices 126 having associated memory 128 for the storage and processing of data collected by the local hardware platform 102. It should be appreciated that the server 126 and memory 128 may take any suitable form known in the art—for example a “cloud-based” distributed server architecture. The network 124 potentially comprises various configurations and protocols including the Internet, intranets, virtual private networks, wide area networks, local networks, private networks using communication protocols proprietary to one or more companies—whether wired or wireless, or a combination thereof. It should be appreciated that the network 124 illustrated may include distinct networks and/or connections: for example a local network over which the user interface may be accessed within the vicinity of the milking facility, and an internet connection via which the cloud server is accessed. Information regarding operation of the system 100 may be communicated to user devices such as a smart phone 130 or a tablet computer 132 over the network 124.

[0093] Referring to FIG. 2, an exemplary sensor 200 is illustrated, which may be used (for example) as one or more of the on-line sensors 116a to 116n. In this exemplary embodiment, the on-line sensor 200 includes an ultrasound sensor device 300, configured to perform ultrasound-based measurements of milk contained therein.

[0094] The sensor 200 includes sample delivery device 202 configured to be connected to a source of the fluid to be sampled—for example milk tube 204 or milk jar 206—and deliver a sample of the fluid to the ultrasound sensor device 300.

[0095] A controller 208 is provided to control the operation of the various components described, receive data obtained by the ultrasound sensor device 300, and communicate over a network such as the network 124.

[0096] FIG. 3A and FIG. 3B illustrate an exemplary embodiment of the ultrasound sensor device 300. The sensor device 300 includes a hollow body in the form of a stainless steel main tube 302, having a first end 304a and a second end 304b. A first port tube 306a is provided proximate the first end 304a, while a second port tube 306b is provided proximate the second end 304b. In this exemplary embodiment, the port tubes 306 extend radially from the main tube 302 in opposing directions. In use, the port tubes 306 function as an inlet/outlet to and from the main tube 302.

[0097] Between the port tubes 306, the exterior of the main tube 302 may be wrapped in coiled heating wires, for example an enamelled fine copper winding 308 around the main tube 302, and a larger nichrome wire winding 310 coiled over the copper winding 308. While not illustrated, it is envisaged that at least the copper windings 308 may also be provided on the port tubes 306. The respective windings 308 and 310 may be connected in series, and current supplied to control temperature of the sensor device 300 and/or fluid being sensed. Further, the resistance of the windings 308 and/or 310 may be used to determine temperature. While not illustrated, it is also envisaged that insulating material may be provided over at least the main tube 302 in order to reduce the influence of ambient temperature and/or to increase efficiency when heating the fluid to measurement temperatures. It is envisaged that the insulating material may not cover the ends of the sensor device 300 to allow for heat dissipation from a first ultrasound transducer 400a at the first end 304a of the main tube 302, and a second ultrasound transducer 400b at the second end 304b.

[0098] The first ultrasound transducer 400a and the second transducer 400b are arranged to face each other along the longitudinal axis of the main tube 302. In use, one of the transducers 400 is configured as a transmitter, while the other is configured as a receiver.

[0099] FIG. 4A to 4C illustrate an exemplary embodiment of the ultrasound transducer 400. The transducer 400 includes a housing having a main body 402 and a cap 404 configured to be secured to the main body 402. Referring to FIG. 4C, the main body 402 includes a first set of threads 406, while the cap 404 includes a second set of threads 408 configured to engage the first set of threads 406. The cap 404 includes a tool engaging portion, for example hexagonal head 410. In this exemplary embodiment, the housing is made of polysulfone, as will be discussed further below.

[0100] Referring to FIG. 4A, the main body 402 includes a slotted portion 412 configured to receive components of the transducer 400. In the exemplary embodiment illustrated, a piezoelectric element holder (referred to herein as piezo holder 414) is provided, having an aperture 416 configured to receive a piezoelectric element 418. In this embodiment, the piezoelectric element 418 is a disk-shaped lead metaniobate piezoelectric element. The acoustic impedance of the piezoelectric element 418 is between 15 to 22 MRayls, more particularly in the order of 16 MRayls. In an exemplary embodiment the piezoelectric element is constructed of 0.5 mm thick APC3285. When heavily damped in the exemplary transducer design the resulting transducer has a centre frequency around 3.75 MHz.

[0101] In this embodiment, the piezo holder 414 is made of a circuit board material for ease of forming electrical connections. The piezo holder 414 includes a rigid portion for locating the piezoelectric element 418 and an elongate flex portion 504 to act as an electrical connection. A piezoelectric contact member (referred to herein as piezo contact 420) is provided beneath the piezo holder 414 to contact the piezoelectric element 418. In this embodiment, the piezo contact 420 is made of RO4003C with a 35 μm electrodeposited copper foil layer, available from Rogers Corporation. In this exemplary embodiment, an electrical contact is provided on the opposing side of the piezo holder 414 (to the piezo contact 420) in the form of a foil strip 422—for example, a copper foil in the order of 33 μm in thickness.

[0102] Above the foil strip 422, a backing element 424 is provided. The backing element 424 is generally cylindrical in shape, having locating wings 426a and 426b on opposing sides. The locating wings 426 align with the slotted portion 412 of the main body 402, to assist with maintaining the position of the backing element 424 during assembly. A PTFE gasket 428 is provided between the backing element 424 and the cap 404.

[0103] Referring to FIG. 4C, below the piezo contact 420 the main body 402 includes a cylindrical shaft 430. The distal end of the shaft 430 has a flat surface 432, which in use is presented to the interior of the main tube 302 (as shown in FIG. 3B). The thickness of the main body 402 from the flat surface 432 to the piezo contact 420 is influenced by several factors. Firstly, the temperature of polysulfone has an effect on acoustic performance (more particularly sound speed), and the main body 402 is subject to heat inputs from the piezoelectric element 418 and windings 308 and 310, as well as fluctuations in the ambient temperature. Secondly, reflections of the acoustic signal will occur at the boundary between the flat surface 432 and the fluid, which if not accounted for will interfere with signal analysis. As such, there is a balance to be struck between reducing the thickness of the polysulfone as a percentage of the overall signal transmission path, and achieving a sufficient thickness so as to delay the reflections.

[0104] Further, there are practical considerations for assembly of the transducer 400—for example, the shaft 430 being of a sufficient length for fitting to the main tube 302 of the sensor device 300. It should also be appreciated that the diameter of the shaft 430 may be sized relative to the internal diameter of the main tube 302 to produce a seal, as well as mechanically securing the transducer 400 to the main tube 320.

[0105] In the exemplary embodiment illustrated in FIG. 3A and 3B, the respective piezoelectric elements of the transducers 400a and 400b are spaced apart at 69 mm (comprising a 59 mm gap between end surfaces, and a polysulfone thickness of about 5 mm). The thickness of the polysulfone of each transducer 400 is about 5 mm, which in combination represents just under 15% of the total path length. It is also considered desirable for reflections to be delayed by at least four wavelengths—i.e. requiring the thickness of the polysulfone to be at least two wavelengths. In a design having a 2.5 MHz low frequency cut-off, and 2240 m/s nominal sound speed in polysulfone, the wavelength of the signal through the main body 402 is 0.896 mm. A 5 mm thickness provides a total path length of eleven wavelengths, which satisfies this design criteria.

[0106] With the acoustic impedance of the piezoelectric element being in the order of 16 MRayls, it is desirable for the acoustic impedance of the backing element 424 to be substantially the same. In the exemplary embodiment described herein, the backing element 424 is made of a tungsten composite, including tungsten particles of a relatively large size (more particularly granulated tungsten powder—such as GW-100270 available from Buffalo Tungsten Inc), and tungsten particles of a relatively small size (more particularly fine tungsten powder—such as C20-491 available from Buffalo Tungsten Inc). It is envisaged that this may assist with improving the ability of the backing element to absorb the acoustic signal over a broader range of frequencies in comparison with a single particle size. Further, the relatively high density of tungsten is considered to aid in achieving a suitable acoustic impedance. In this exemplary embodiment, the tungsten particles are suspended in an epoxy resin, for example EpoTek 301 available from Epoxy Technology Inc. In an exemplary embodiment, the ratio of GW-100270:C20-491:EpoTek 301A may be in the order of 56:7:3.5 (with the second part of the epoxy EpoTek 301B later added at 0.875). It is envisaged that the unset mixture may be spun in a centrifuge so as to promote settling of the tungsten particles towards an end of the backing element 424 which is proximate the piezoelectric element 418 in use.

[0107] The polysulfone of the main body 402 may be Sustason PSU rod stock produced from non UV-stabilised polysulphone resin (available from Rochling Sustaplast SE & Co. KG), which has a nominal acoustic impedance in the order of 2.78 MRayl. Due to the differential in acoustic impedance between the polysulfone and the piezoelectric material it is desirable to include an impedance matching layer. The piezo contact 420 is configured for this purpose. An ideal matching layer should have an acoustic impedance (Z.sub.0) that is the square root of the product of the acoustic impedance of the adjacent materials (i.e. Z.sub.1 and Z.sub.2)—i.e. Z.sub.0=√(Z.sub.1.Math.Z.sub.2). For the lead metaniobate piezoelectric material and polysulfone interface of the present example, the ideal acoustic impedance of the piezo contact 420 would be 6.67 MRayls. While it is generally preferable for the acoustic impedance of the matching layer to be as close as possible to the ideal value, in practice the impedance may be within a wider range and still produce a useful result—particularly where other design constraints are present.

[0108] The thickness of the piezo contact 420 is also designed to provide quarter wave matching with the ultrasound signal. More particularly, the thickness of the piezo contact 420 may be between 20 to 30% of the signal wavelength at the centre operating frequency of the transducer 400 (i.e. 3.75 MHz). As such, with a nominal acoustic impedance of about 6 MRayls and thickness of about 0.203 mm, the RO4003C piezo contact 420 is considered suitable for impedance matching. Further, the RO4003C material can be supplied with an electrodeposited copper foil, which is used in the exemplary embodiment to provide electrical contact between the piezo holder 414 and the bottom face of the piezoelectric element 418. In the exemplary embodiment the electrodeposited foil is 35 μm thick.

[0109] FIG. 5 illustrates a piezoelectric assembly 500, including the piezo holder 414, piezoelectric element 418, piezo contact 420, and foil strip 422 as previously described. In an exemplary embodiment, prior to assembly of the transducer 400, the piezo contact 420 may be soldered to the piezo holder 414, and one end of the foil strip 422 soldered to the piezo holder 414. One or more electronic components 502 may also be soldered to the piezo holder 414. It may be seen that the piezo holder 414 also includes a flex portion 504—which may be used to provide electric connections to associated circuitry. The resulting sub-assembly is used to assist in assembly of the transducer 400.

[0110] During assembly, the piezoelectric element 418 is inserted into the aperture 416 of the piezo holder 414, beneath the foil strip 422. The thickness of the piezo holder 414 is such that the piezoelectric element 418 projects above it, to ensure contact with the foil 422 (and therefore backing element 424). The piezoelectric assembly 500 is then inserted into the slotted portion 412 of the main body 402. The slotted portion 412 and piezoelectric assembly 500 are shaped such that the piezoelectric element 418 is centred over the shaft 430 of the main body 402.

[0111] During assembly, an epoxy adhesive (for example, Scotch-Weld™ Epoxy Adhesive EC-2216 B/A available from 3M Company) is used between the piezoelectric element 418, the piezo contact 420 and the foil strip 422 for good acoustic contact, and between the piezo contact 420 and the main body 402, and between the foil strip 422 and the backing element 424.

[0112] The backing element 424 is inserted into the slotted portion 412, contacting the top of the foil strip 422. The cap 404 is then screwed on to the main body 402 until a specified torque is achieved, to squeeze the epoxy from between the various layers and provide a desired pressure as the epoxy sets. It is envisaged that the residual epoxy may be sufficiently thin so as to have a negligible effect on acoustic transmission properties or electrical contact. During assembly a fillet of epoxy is also applied to cover the electronic component 502 and portions of the piezo holder 414 adjacent the housing, to seal and encapsulate the transducer components.

[0113] FIG. 6 illustrates the frequency response 600 of an exemplary ultrasound transducer 400 constructed in accordance with the description above. The ultrasound transducer 600 has a centre frequency 602 of about 3.75 MHz, with a lower −6 dB frequency limit 604 of about 2.5 MHz and an upper −6 dB frequency limit 606 of about 4.9 MHz. This provides a −6 dB bandwidth of about 2.4 MHz, which may be expressed as a −6 dB percentage bandwidth of about 64%. For completeness, it will be appreciated that variation in the tested bandwidth may be expected between different batches of the transducer, and between individual examples of the transducer design.

[0114] All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. Reference to any prior publications in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that that prior art forms part of the common general knowledge in the field of endeavour in any country in the world.

[0115] Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like, are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense, that is to say, in the sense of “including, but not limited to”. The entire disclosures of all applications, patents and publications cited above and below, if any, are herein incorporated by reference.

[0116] The invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, in any or all combinations of two or more of said parts, elements or features.

[0117] Where in the foregoing description reference has been made to integers or components having known equivalents thereof, those integers are herein incorporated as if individually set forth.

[0118] It should be noted that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the invention and without diminishing its attendant advantages. It is therefore intended that such changes and modifications be included within the present invention.

[0119] Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof.