PRESSURE SENSOR AND INSTRUMENT UTILIZING SAME

• US 3,888,117 A
• Filed: 07/16/1973
• Issued: 06/10/1975
• Est. Priority Date: 07/16/1973
• Status: Expired due to Term

• Current Assignee: Warren F. Lewis
• Original Assignee: Warren F. Lewis
• Inventors: Lewis, Warren F.
• Primary Examiner(s): Ruehl, Charles A.
• Application Number:
  US05/379,776
• Time in Patent Office: 694 Days
• Field of Search: 73/141A,161,88B,15A,379,1R 128/20 200/85R,86R,159B 340/236,272
• US Class Current: 73/862.53
• CPC Class Codes: A61B 17/02 for holding wounds open; Tractors specula A61B1/32 ; drainage appliances for wounds A61M27/00
• CPC Class Codes: A61B 2090/065 for measuring contact or contact pressure
• CPC Class Codes: G01L 9/0002 using variations in ohmic resistance G01L9/0051 takes precedence

Abstract

A pressure indicating instrument including first and second conductors and a layer of compressible insulating material interposed between the conductors for normally holding the conductors out of electrical contact. The layer is compressible to allow the conductors to move toward each other and into electrical contact. An indicator is coupled to the conductors for indicating whether the conductors are in electrical contact.

Claims

1. A pressure indicating instrument comprising:

a pressure sensor including first and second conductors and a compressible insulator interposed between said conductors, said insulator normally holding said conductors out of electrical contact;

said insulator being compressible in response to a compressive pressure tending to bring the first and second conductors closer together;

at least a portion of at least one of said first and second conductors being adapted to contact the other of said first and second conductors in response to a predetermined amount of compression of said insulator, said predetermined amount of compression of said insulator corresponding to a predetermined magnitude of the compressive pressure on said pressure sensor;

indicator means coupled to said pressure sensor and being responsive to said conductors being in electrical contact for providing an indication of the presence or absence of said predetermined magnitude of the compressive pressure on said pressure sensor;

teSting means disposed relative to the first and second conductors and being operable to enable the indicator means to provide the indication even when the insulator is not compressed; and

said pressure sensor including a flexible jacket having a surface with non-stick characteristics, said jacket enclosing at least substantial sections of said conductors and said insulator, said compressive pressure being transmittable to said insulator through said flexible jacket.

2. A pressure indicating instrument as defined in claim 1 wherein said insulator includes resilient open cell foam material.

3. A pressure indicating instrument as defined in claim 1 wherein said first conductor includes a substantially rigid conductive member which forms a supporting base for said insulator.

4. A pressure sensor comprising:

a substantially rigid base, at least a portion of the base being conductive;

a layer of resiliently compressible open cell foam material having insulating properties and a controlled resiliency providing the layer with known compression characteristics;

a conductor, said layer being intermediate said conductor and said conductive portion, said layer normally insulating said conductor from said conductive portion, said conductive portion and said conductor being electrically connectible to an external circuit whereby it can be ascertained if said conductor and said conductive portion are in electrical contact;

a flexible jacket enclosing at least substantial sections of said base, said conductor and said layer whereby in response to an external pressure greater than a predetermined magnitude on the jacket, the layer resiliently compresses to permit electrical contact between said conductive portion and the conductor; and

said base being elongated and having inner and outer ends, said base having a curved adjacent said outer end, and said conductive portion including a face of said base on the inside of the curve of said curved portion.

5. A pressure sensor as defined in claim 4 wherein, said jacket is substantially impervious to liquids, and the outer surface of at least a substantial portion of the pressure sensor has a non-stick characteristic.

6. A pressure sensor as defined in claim 4, said pressure sensor being is a retractor element for a brain retractor.

7. A pressure sensor as defined in claim 4 wherein said layer has portions defining at least one aperture and characteristics responsive to the external pressure greater than the predetermined magnitude for compressing to permit contact between the conductor and the conductive portion through said aperture.

8. A pressure sensor as defined in claim 7 wherein said conductor includes an elongated conductive element and at least one conductive member attached to the conductive element, said conductive member being positioned relative to said aperture for movement toward said conductive portion upon compression of said layer.

9. A pressure sensor as defined in claim 4 wherein said layer has first and second apertures therein, said conductor including an elongated conductive element and first and second conductive members attached to said conductive element and positionable in the first and second apertures, respectively.

10. A pressure sensor as defined in claim 4 wherein, said pressure sensor is a retractor element for a brain retractor, said jacket is substantially impervious to liquids, and the outer surface of at least a substantial portion of the pressure sensor having a non-stick characteristic.

11. An instrument comprising:

a handle having a recess therein;

a tool having an inner end, said inner end being insertable into said recess of said handle of a locked position;

means for releasably retaining the inner end of the tool in said locked position in said recess whereby the tool is removably remounted on said handle;

circuit means for providing an indication when said tool encounters a predetermined condition, a first Portion of said circuit means being carried by said handle and a second portion of said circuit means being carried by said tool;

indicator means for providing an indication when said first portion of said circuit means is closed; and

means responsive to partial insertion of the inner end of the tool into said recess to close said first portion of said circuit means thereby causing said indicator means to provide said indication whereby a check of said first portion of said circuit means is obtained.

12. An instrument as defined in claim 11 including means responsive to the inner end of the tool being in said locked position to open said first portion of said circuit means.

13. An instrument as defined in claim 11 including first and second contacts in said housing on opposite sides of the recess, at least one of said contacts being movable toward and away from the other of said contacts, said inner end of said tool including a conductive section sized to bridge the gap between said contacts and a second section which will not ordinarily complete the circuit between said contacts.

14. A brain retractor comprising:

a handle;

an elongated retractor section;

means for removably mounting the elongated retractor section on the handle;

said elongated retractor section having a curved section adjacent the outer end thereof, said elongated retractor section including a flexible substantially liquid impervious jacket, the outer surface of at least a substantial section of said elongated retractor having a non-stick said elongated retractor section including a pressure switch inside said jacket, said pressure switch being in a first state when the pressure on the elongated retractor section is less than a predetermined value and being in a second state when the pressure on the elongated retractor section is greater than said predetermined value; and

circuit means carried by the handle and the retractor section and coupled to the pressure switch for indicating when the pressure switch is in said first state or said second state.

15. A brain retractor as defined in claim 14 wherein said pressure switch includes a layer of resilient foam material and first and second conductors on opposite sides of said foam material.

16. A pressure sensor adapted for use in moving an object with a pressure not greater than a particular pressure, comprising:

first conductor means having a substantially elongated, rigid configuration and a curved portion at one end thereof facilitating engagement of the object by the pressure sensor;

second conductor means disposed along at least the curved portion of the first conductor means and being responsive to the pressure of the object on the pressure sensor to move toward the first conductor means;

spacing means disposed intermediate the first conductor means and the second conductor means for normally separating the first conductor means and the second conductor means, the spacing means havng properties for being resiliently compressed in response to the pressure of the object on the pressure sensor and having properties for being compressed to a position permitting the engagement of the first conductor means and the second conductor means in response to a pressure greater than the particular pressure; and

indicating means for signaling the engagement of the first conductor means and the second conductor means to indicate a pressure on the object greater than the particular pressure.

17. The pressure sensor recited in claim 16 wherein the first conductor means comprises:

an elongated base member having substantially rigid characteristics and a curved portion at one end thereof, the base member including a particular surface on the inside of the curved portion; and

a first conductor disposed along at least the particular surface for engagement by the second conductor means in response to a pressure greater than the particular pressure.

18. The pressure sensor recited in claim 16 further comprising jacket means disposed to cover at least substantial sections of the first conductor means, second conductor means, and spacer means, the jacket means having properties for being substantially impervious to liquids and having an outer surface with a non-stick characteristic.

19. The pressure sensor recited in claim 18 wherein the jacket means comprises:

a first jacket disposed to cover at least substantial sections of the first conductor means, second conductor means, and spacing means, the first jacket having properties for being substantially impervious to liquids; and

a second jacket disposed to cover at least substantial sections of the first jacket, the second jacket having an outer surface with a non-stick characteristic.

20. The pressure sensor recited in claim 16 wherein the first conductor means, second conductor means, and spacing means form a probe and the sensor further comprises:

a handle;

the signaling means being disposed in the handle and having a first terminal and a second terminal which are electrically connectible to activate the signaling means; and

the probe being insertable into the handle to a normal position in which the first conductor means engages the first terminal of the signaling means and the second conductor means engages the second terminal of the signaling means;

whereby the first terminal and the second terminal are electrically connected to activate the signaling means when the second conductor means engages the second conductor means in response to a pressure greater than the particular pressure.

21. The pressure sensor recited in claim 20 wherein the probe is insertible into the handle to a test position and one of the first conductor means and second conductor means in the test position contacts both the first terminal and the second terminal to activate the signaling means and thereby test the signaling means. 22. The pressure sensor set forth in claim 16 wherein the first conductor means, second conductor means, and spacing means form at least a portion of a probe, and the sensor further comprises:

a handle;

means attached to the probe at the end of the first conductor means opposite the curved portion for connecting the probe to the handle; and

at least a portion of the indicating means being carried by the handle.