SELF-CALIBRATING PRESSURE SENSOR

• US 20090036754A1
• Filed: 07/29/2008
• Published: 02/05/2009
• Est. Priority Date: 07/31/2007
• Status: Active Grant

• Current Assignee: Captomed Eurl, Centre National De La Recherche Scientifique
• Original Assignee: Captomed Eurl, Centre Natonal De La
• Inventors: Yameogo, Pierre, Montoriol, Pierre, Pons, Patrick
• Granted Patent: US 8,622,923 B2
• Time in Patent Office: Days
• US Class Current: 600/301
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 5/02156 Calibration means
• CPC Class Codes: A61B 5/031 Intracranial pressure
• CPC Class Codes: G01L 27/005 Apparatus for calibrating pressure sensors
• CPC Class Codes: G01L 9/0054 integral with a semiconducting diaphragm

Abstract

The invention has as its object a self-calibrating device for measuring intracorporeal pressure, comprising:

• • A pressure sensor that comprises i) a test body (11) of which a segment of smaller thickness constitutes a membrane that can deform under the action of the pressure of the medium, whereby said membrane is equipped with at least one piezoelectric transducer that can translate a mechanical stress into an electrical signal, and ii) a polarization contact,
  • An actuator that is connected to a voltage source, comprising a non-deformable base, whereby at least one surface of said actuator is polarizable, and whereby said pressure sensor is placed above said actuator so that the membrane is directly at the base of the polarizable surface (22).

Preferably, said pressure sensor comprises four doped-silicon piezoresistive gauges, integrated into the zones of greater deformation of a silicon membrane. It is calibrated without it being necessary to withdraw it from the medium in which it is placed by charging the actuator, which comes to exert a known pressure on the membrane. This operation can be repeated as often as necessary.

For medical use, the device can be encapsulated in a resin sheath and attached to the end of a catheter that is designed to be implanted in a patient'"'"'s body.

Claims

1. Self-calibrating device for measuring intracorporeal pressure, characterized in that it comprises:

A pressure sensor (1) that comprises i) a test body (11) of which a segment of smaller thickness constitutes a membrane (12) that can deform under the action of the pressure of the medium, whereby said membrane is equipped with at least one piezoelectric transducer (13) that can translate a mechanical stress into an electrical signal, and ii) a polarization contact (14),

An actuator (2) that is connected to a voltage source, comprising a non-deformable base (21), whereby at least one surface (22) of said actuator is polarizable,

and whereby said pressure sensor is placed above said actuator so that the membrane (12) is directly at the base of the polarizable surface (22).

2. Device according to claim 1, wherein the sensor (1) is kept above the actuator (2) by a rigid connection (3), whereby the space that is encompassed between the membrane (12) and the polarizable surface (22) constitutes a cavity (4) of specified size.

3. Device according to claim 1, wherein the actuator (2) comprises insulating means separating the polarizable surface (22) and the test body (11).

4. Device according to claim 1, wherein the actuator (2) comprises, on a non-deformable insulating substrate (23), a metal electrode (24) that is connected to a voltage source.

5. Device according to claim 4, wherein the insulating substrate (23) consists of a material that is selected from among glass, borosilicate glass, vitreous ceramic, and insulating silicon.

6. Device according to claim 1, wherein the actuator (2) comprises a non-deformable conductive substrate (25) that is connected to a voltage source and separated from the test body by at least one insulating element (26).

7. Device according to claim 6, wherein the conductive substrate (25) is made of conductive silicon, and said at least one insulating element (26) is made of silicon oxide.

8. Device according to claim 1, wherein the test body (11) and the membrane (12) of said pressure sensor are made of conductive silicon.

9. Device according to claim 1, wherein said pressure sensor comprises at least two, and preferably four, piezoelectric transducers (13) that are placed in the zones of greater deformation of the membrane (12).

10. Device according to claim 1, wherein said at least one piezoelectric transducer is selected from among the piezoresistive gauges, the pn-junction diodes, the bipolar transistors, or the field-effect transistors.

11. Device according to claim 1, wherein said piezoresistive gauges are made of doped silicon that is integrated into said silicon membrane.

12. Device according to claim 1, wherein the cavity (4) is extended by an open channel (6) into the atmosphere.

13. Device according to claim 1, wherein the cavity (4) is hermetically sealed by a polymer compound (5) and devoid of air.

14. Device according to claim 1, wherein it also comprises a temperature sensor.

15. Device according to claim 1, wherein it is connected to a central unit that comprises electric signal processing means generated by the pressure sensor (1) and optionally by the temperature sensor.

16. Device according to claim 1, wherein it is attached at the end of a catheter and encapsulated in a resin sheath that comprises a window at the level of the membrane (12).

17. Catheter for medical use, wherein the end that is designed to be implanted in a patient'"'"'s body comprises a self-calibrating device for measuring the intracorporeal pressure according to claim 1.

18. Device according to claim 2, wherein the actuator (2) comprises insulating means separating the polarizable surface (22) and the test body (11).