An apparatus and method

Patent metadata

Field	Value
Publication number	US-2021100513-A1
Application number	US-201916971129-A
Country	US
Kind code	A1
Filing date	Feb 20, 2019
Priority date	Feb 20, 2018
Publication date	Apr 8, 2021
Grant date	—

Abstract

An implantable cardiovascular pressure sensor comprising a rigid enclosure sealed by a flexible membrane; and an elongate compliant member comprising a piezoelectric material, the member having a width and a length greater than the width, and two ends separated by the length and two sides separated by the width; wherein the flexible membrane is coupled to the elongate compliant member to transfer external fluid pressure load to the elongate compliant member to cause deflection of the elongate compliant member in response to changes in the external fluid pressure; the pressure sensor further comprising a first acoustic wave device provided by the piezoelectric material of the elongate compliant member for sensing said deflection.

First claim

What is claimed is:

1 . An implantable cardiovascular pressure sensor comprising:
a rigid enclosure sealed by a flexible membrane; and an elongate compliant member comprising a piezoelectric material, the member having a width and a length greater than the width, and two ends separated by the length and two sides separated by the width; wherein the flexible membrane is coupled to the elongate compliant member to transfer external fluid pressure load to the elongate compliant member to cause deflection of the elongate compliant member in response to changes in the external fluid pressure; the pressure sensor further comprising:
a first acoustic wave device provided by the piezoelectric material of the elongate compliant member for sensing said deflection.

2 . The sensor of claim 1 wherein the first acoustic wave device comprises a surface acoustic wave, SAW, device disposed on an internal face of the elongate compliant member.

3 . The sensor of claim 2 wherein the SAW device comprises an interdigitated transducer having a plurality of interdigitated fingers spaced apart in the direction of the length of the compliant member.

4 . The sensor of claim 1 , wherein the sensor comprises a base in the rigid enclosure.

5 . The sensor of claim 1 , wherein the rigid enclosure comprises piezoelectric material and the sensor comprises a second acoustic wave device.

6 . The sensor of claim 5 wherein the second acoustic wave device is disposed on at least one of:
an internal surface of the rigid enclosure; and
the base.

7 . (canceled)

8 . The sensor of claim 5 wherein the elongate compliant member and a substrate of the second acoustic wave device comprise the same piezoelectric material;
wherein the rigid enclosure provides the base;
wherein the flexible membrane comprises a strain corrugated diaphragm;
wherein the diaphragm comprises at least one ridge or groove;
wherein the diaphragm comprises a corrugated region of the flexible membrane;
wherein the membrane comprises at least one of:
a biocompatible metal such as gold; and
a layered polymer structure;
a layer of polymer and a layer of a sealing material;
a layer of polymer and a layer of a sealing material comprising a plurality of layers of the polymer and/or the sealing material provided in alternate layers of the membrane;
a layer of polymer and a layer of a sealing material wherein the sealing material comprises an inorganic or glassy oxide; and
a layered polymer structure wherein the layers are provided by atomic or vapour layer deposition.

9 - 18 . (canceled)

19 . The sensor of claim 1 wherein the acoustic wave device comprises a bulk acoustic wave, BAW, device.

20 . The sensor of claim 19 wherein the BAW device comprises electrodes on the sides of the elongate compliant member for providing a voltage across its width.

21 . The sensor of claim 19 wherein a rigid wall of the rigid enclosure comprises piezoelectric material and the sensor comprises a second bulk acoustic wave device provided by the rigid wall, wherein the rigid enclosure comprises a base and wherein the base comprises the rigid wall.

22 . The sensor of claim 1 wherein the two ends are rigidly fixed or simply supported within the enclosure; and/or
wherein deflection of the elongate compliant member comprises a beam deflection.

23 . (canceled)

24 . An implantable cardiovascular pressure sensor comprising:
an enclosure, having a wall comprising a compliant region, integral with the wall, and arranged to be displaced into or outward from the enclosure in response to changes in a pressure difference across the wall; and a deflectable piezoelectric member coupled to the compliant region to be deflected in response to displacement of the compliant region, and an acoustic wave transducer, wherein the deflectable piezoelectric member provides the substrate of the acoustic wave transducer.

25 . The sensor of claim 24 , wherein the compliant region comprises a flexible feature in the wall;
wherein the flexible feature comprises at least one of:
the flexible feature comprises at least one of a thinner part of the wall, and a corrugation in the wall;
the flexible feature provides a boundary between the compliant region and a less compliant region of the wall;
the flexible feature provides a boundary between the compliant region and a less compliant region of the wall and wherein the flexible feature circumscribes the compliant region.

26 - 28 . (canceled)

29 . The sensor of claim 1 wherein the wall and the compliant region are integrally formed from the same material; and
wherein the wall and the compliant region comprise a biocompatible metal, such as gold.

30 . (canceled)

31 . The sensor of claim 1 comprising a second acoustic wave transducer, arranged to provide a reference for the first acoustic wave transducer.

32 . The sensor of claim 31 , wherein being arranged to provide a reference comprises at least one of:
the second acoustic wave transducer being disposed on a piezoelectric substrate that is arranged to be deflected differently in response to the pressure difference than a substrate of the first acoustic wave transducer; said piezoelectric substrate being arranged so that it is deflected less by displacement of the compliant region than the substrate of the first acoustic wave transducer, for example wherein it is rigid or held in a fixed position; and the second acoustic wave transducer being provided with the same substrate as the first acoustic wave transducer.

33 - 34 . (canceled)

35 . The sensor of claim 1 wherein the deflectable piezoelectric member is supported at at least one end, and has a length cantilevered from said support that is more than its width.

36 . The sensor of claim 35 wherein the deflectable piezoelectric member is a beam.

37 . The sensor of claim 1 wherein the enclosure comprises a deposited body, formed by deposition on a mandrel to provide the wall and compliant region;
wherein the wall provides at least one side of the enclosure;
wherein the enclosure is closed by a dielectric end cap hermetically sealed to an end of the enclosure; and
wherein the dielectric end cap comprises a fixture for holding an antenna, wherein the sensor comprises an electrical connection between the fixture and the first acoustic wave transducer.

38 - 40 . (canceled)

41 . A method of forming an implantable cardiovascular pressure sensor, the method comprising:
depositing a layer of material onto a mandrel comprising a forming feature arranged so that the layer provides a wall comprising a compliant region integral with the wall; detaching the wall from tile mandrel to form an enclosure comprising said wall; coupling a deflection sensor to the compliant region, inside said enclosure, to sense deflection of Um compliant region; and sealing said enclosure so that the compliant region can be displaced into or outward from the enclosure in response to changes in a pressure difference across the wall.

42 . The method of claim 41 , wherein the deflection sensor comprises a deflectable piezoelectric member operable to be deflected in response to displacement of the compliant region, and an acoustic wave transducer, wherein the deflectable piezoelectric member provides the substrate of the acoustic wave transducer.

Assignees

• Imperial Innovations Ltd
• Ip2Ipo Innovations Ltd

Inventors

• Bahmanyar Mohammad Reza
• Mcleod Christopher Neil

Classifications

• A61B2562/0204

  Acoustic sensors · CPC title

• G01L9/0085

  using variations in inductance · CPC title

• B81B7/0061

  suitable for fluid transfer from the MEMS out of the package or vice versa, e.g. transfer of liquid, gas, sound · CPC title

• A61B5/6869 Primary

  Heart · CPC title

• A61B2562/164

  the sensor is mounted in or on a conformable substrate or carrier · CPC title