Method for protecting a resonating sensor

• US 8,356,399 B2
• Filed: 11/19/2007
• Issued: 01/22/2013
• Est. Priority Date: 08/27/2003
• Status: Active Grant

• Current Assignee: MicroTech Medical Technologies Ltd.
• Original Assignee: MicroTech Medical Technologies Ltd.
• Inventors: Kaplan, Shay
• Primary Examiner(s): Kim, Paul D
• Application Number:
  US11/941,992
• Publication Number:
  US 20080066550A1
• Time in Patent Office: 1,891 Days
• Field of Search: 295/921, 295/94, 296/091, 181/171, 181/172, 310/321, 310/328, 310330-333, 381/396, 381/398, 333/150, 333/187, 333193-196
• US Class Current: 29/594
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: G01L 9/001 of an element not provided for in the following subgroups of G01L9/0008
• CPC Class Codes: Y10T 29/49005 Acoustic transducer
• CPC Class Codes: Y10T 29/4908 Acoustic transducer

Abstract

A method of protecting a resonating sensor is described. The protected resonating sensor may include at least one passive ultrasonically excitable resonating sensor unit. Each sensor unit has one or more vibratable members having a resonating frequency that varies as a function of a physical variable in a measurement environment. The sensor is protected by forming one or more protective chambers defined between a compliant member and the vibratable member(s). A substantially non-compressible medium is disposed within the protective chamber(s). The compliant member has a first side that may be exposed to a measurement environment and a second side that may be exposed to the substantially non-compressible medium. The substantially non-compressible medium may be a liquid or gel and is in contact with the vibratable member(s). When the medium is a liquid, the chamber is sealed. When the medium is a gel, the chamber may be sealed or non-sealed.

Claims

1. A method for protecting an implantable, passive ultrasonically excitable resonating sensor from deposition of extraneous materials thereupon, the method comprising:

providing a sensor having a passive ultrasonically excitable resonating sensor unit, said sensor unit including a substrate and a vibratable member, and a recess disposed between said vibratable member and said substrate to define a first chamber, said first chamber being a sensor unit chamber, said vibratable member having a resonance frequency that varies as a function of a physical variable in a measurement environment in which said sensor is disposed in response to an interrogating ultrasound beam; and

forming a second chamber having walls to protect said vibratable member from the deposition of extraneous material thereupon, said second chamber defined between said vibratable member and a compliant member and filled with a substantially non-compressible medium, said compliant member having a first side and a second side and forming at least part of the walls of said second chamber, said vibratable member forming at least part of the walls of said second chamber;

wherein said substantially non-compressible medium is in contact with said compliant member and said vibratable member;

wherein said first side of said compliant member is in contact with a measurement environment to form a first interface when said sensor is disposed in said measurement environment and said second side of said compliant member is in contact with said substantially non-compressible medium to form a second interface; and

wherein said compliant member comprises a structure that limits reflection of said interrogating ultrasound beam at said first interface and said second interface, said structure selected from the group consisting of a material, a thickness, and a material and thickness.

2. The method according to claim 1, wherein said compliant member comprises a compliant material selected from a polymer based material, a plastic material, Kapton®

, a polyurethane based polymer, an ethylvinyl acetate based polymer, Echothane®

CPC-41, Echothane®

CPC-29, Echothane®

, and a Parylene®

based polymer.

3. The method according to claim 1, wherein said forming step comprises sealingly enclosing said vibratable member of said resonating sensor unit in said second chamber to form a sealed second chamber.

4. The method according to claim 1, wherein said substantially non-compressible medium is selected from water, a water based solution, a liquid comprising one or more silicon based compounds and a gel, Dow Corning 710®

Silicon Fluid, Fluorinert FC40 fluid, Fluorinert FC 70 fluid, a liquid having a low vapor pressure, and combinations thereof.

5. The method according to claim 1, wherein the acoustic impedance of said substantially non-compressible medium is close to or equal to the acoustic impedance of a medium contained in said measurement environment in which said protected sensor is disposed.

6. The method according to claim 1, wherein the acoustic impedance of said compliant member is close to or equal to the acoustic impedance of a medium contained in said measurement environment in which said protected sensor is disposed.

7. The method according to claim 1, wherein said resonating sensor unit is selected from a pressure sensor unit, a temperature sensor unit, a sensor for sensing the concentration of a chemical species in a measurement environment, and combinations thereof.

8. The method according to claim 1, wherein said forming step includes:

disposing said resonating sensor unit in a housing, filling said housing with said substantially non-compressible medium, and attaching said compliant member to said housing to form said second chamber.

9. The method according to claim 8, wherein said attaching comprises sealingly attaching said compliant member to said housing to form said second chamber.

10. The method according to claim 8, wherein said step of disposing comprises attaching said resonating sensor unit to said housing.

11. The method according to claim 1, wherein said forming step includes:

disposing said resonating sensor unit in a housing, attaching said compliant member to said housing to form said second chamber, and filling said second chamber with said substantially non-compressible medium.

12. The method according to claim 11, wherein said forming step further includes sealing said second chamber to form a sealed second chamber.

13. The method according to claim 11, wherein said step of disposing comprises attaching said resonating sensor unit to said housing.

14. The method according to claim 11, wherein a part of said housing forms at least part of the walls of said second chamber, and said filling includes introducing said substantially non-compressible medium into said second chamber through an opening formed in said part of said housing.

15. The method according to claim 1, wherein said second chamber is selected from

a second chamber formed within a sensor anchoring device, and

a second chamber comprising part of a sensor anchoring device.

16. The method according to claim 15, wherein said sensor anchoring device is selected from a sensor anchor, a sensor positioner, an implantable graft, a sensor fixating device, an implant, an implantable device, an implantable graft, a part of an implantable device, a pacemaker, part of a pacemaker, a defibrillator, part of a defibrillator, an implantable electrode, an insertable electrode, an endoscopic device, part of an endoscopic device, an autonomous endoscopic device, a part of an autonomous endoscopic device, a tethered endoscopic device, a part of a tethered endoscopic device, an implantable catheter, an insertable catheter, a stent, a part of a stent, a guide-wire, a part of a guide-wire, an implantable therapeutic substance releasing device, and an insertable therapeutic substance releasing device.

17. The method according to claim 1, wherein said forming step includes:

affixing a spacer member to said resonating sensor unit,

attaching said compliant member to said spacer member to form said second chamber, and

filling said second chamber with said substantially non-compressible medium.

18. The method according to claim 17, wherein said attaching is performed before said filling, and wherein said forming step further includes sealing said second chamber after said filling to form a sealed second chamber.

19. The method according to claim 17, wherein said attaching is performed after said filling.

20. The method according to claim 19, wherein said attaching comprises sealingly attaching said compliant member to said spacer member to form a sealed second chamber.

21. The method according to claim 19, wherein said attaching includes forming in situ said compliant member on said spacer member and on said substantially non-compressible medium to form said second chamber.

22. The method according to claim 19, wherein said in situ forming comprises depositing said compliant member on said spacer member and on said substantially non-compressible medium using a chemical vapor deposition method to form said second chamber.

23. The method according to claim 21, wherein said in situ forming comprises sealingly forming said compliant member on said spacer member and on said substantially non-compressible medium to form said sealed second chamber.

24. The method according to claim 17, wherein said attaching comprises sealingly producing in-situ said compliant member on said spacer member and on said substantially non-compressible medium using a chemical vapor deposition method to form said sealed second chamber.

25. The method according to claim 17, wherein said spacer member forms at least part of said walls of said second chamber and said filling is performed after said attaching, and wherein said filling includes introducing said substantially non-compressible medium into said second chamber through an opening in said spacer member.

26. The method according to claim 25, wherein said forming step further includes sealing said opening after said filling.

27. The method according to claim 25, wherein said introducing includes:

creating a vacuum within said second chamber,

disposing said sensor in a liquid to cover said opening with said liquid, and

allowing said liquid to fill said second chamber to produce said substantially non-compressible medium.

28. The method according to claim 27, wherein said liquid is a gel-forming liquid, said forming step further including allowing said gel-forming liquid to form a gel in said second chamber.

29. The method according to claim 28, wherein said gel-forming liquid is selected from:

a liquefied form of said gel capable of gelling to form said gel, and a liquid gel precursor comprising reactants capable of reacting to form said gel.

30. The method according to claim 1, further including the step of applying a covering layer on at least part of said protected sensor to modify the surface properties of at least part of the surface of said protected sensor.

31. The method according to claim 30, wherein said covering layer is applied to said compliant member to change the surface properties thereof.

32. The method of claim 30, wherein said surface properties are selected from physical surface properties, chemical surface properties, electrochemical surface properties, biological surface properties, rheological surface properties, surface resistance to deposition of cells or tissues thereon, and any combinations thereof.

33. The method according to claim 1, further including the step of treating at least part of the surface of said protected sensor for modifying the surface properties of said at least part of said protected sensor.

34. The method according to claim 33, wherein said step of treating is performed on said compliant member to change the surface properties thereof.

35. The method according to claim 33, wherein said surface properties are selected from physical surface properties, chemical surface properties, electrochemical surface properties, biological surface properties, rheological surface properties, surface resistance to deposition of cells or tissues thereon, and any combinations thereof.

36. The method according to claim 33, wherein said step of treating comprises chemically treating said at least part of the surface of said protected sensor for modifying the surface properties thereof.

37. The method according to claim 1, wherein said substantially non-compressible medium is a gel.

38. The method according to claim 37, wherein said gel is selected from the group consisting of a synthetic gel, a natural gel, a hydrogel, a lipogel, a hydrophobic gel, a hydrophilic gel, a biocompatible gel, a hemocompatible gel, a polymer based gel, a cross-linked polymer based gel and combinations thereof.

39. The method of claim 1, wherein said compliant member has an acoustic impedance that matches the acoustic impedance of said non-compressible medium.

40. The method of claim 1, wherein said compliant member has an acoustic impedance in the range of 1.5-1.54 MRayls.

41. The method according to claim 1, wherein said forming step includes:

filling said second chamber with said substantially non-compressible medium, and attaching said compliant member to said sensor to form said second chamber.

42. The method according to claim 41, wherein said filling is performed after said attaching, and said filling includes introducing said substantially non-compressible medium into said second chamber through an opening formed in said walls other than said at least one vibratable member of said at least one second chamber.

43. The method according to claim 42, wherein said substrate includes a ridge, said compliant member is attached to said ridge prior to said filling, and said opening is located in said ridge.

44. The method according to claim 42, wherein said second chamber comprises part of a sensor anchoring device, and said opening is located in a suitable part of said sensor anchoring device.

45. The method according to any one of claim 14, 42, 43 or 44, wherein said forming step further includes sealing said opening after said filling to form a sealed second chamber.

46. The method according to claim any one of claim 14, 42, 43 or 44, wherein said introducing includes:

creating a vacuum within said second chamber,

disposing said sensor in a liquid to cover said opening with said liquid, and

allowing said liquid to fill said second chamber to produce said substantially non-compressible medium.

47. The method according to claim 46, wherein said liquid is a gel-forming liquid and wherein the method further includes the step of allowing said gel-forming liquid to form a gel in said second chamber.

48. The method of claim 47, wherein said gel-forming liquid is selected from:

a liquefied form of said gel capable of gelling to form said gel, and a liquid gel precursor comprising reactants capable of reacting to form said gel.

49. The method of claim 48, wherein said gel-forming liquid is a liquefied form of said gel which was liquefied by heating said gel, and wherein said gel is formed within said second chamber upon cooling of said gel-forming liquid.