Pressure dome with compliant chamber

• US 4,572,204 A
• Filed: 03/21/1984
• Issued: 02/25/1986
• Est. Priority Date: 03/21/1984
• Status: Expired due to Term

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Stephens, Thomas P.
• Primary Examiner(s): Cohen, Lee S.
• Assistant Examiner(s): Sykes, Angela D.
• Application Number:
  US06/591,728
• Time in Patent Office: 706 Days
• Field of Search: 128/672-673, 128/675, 128/748, 73/707
• US Class Current: 600/488
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: G01L 9/0072 using variations in capacitance

Abstract

A pressure dome in which the wall forming the cavity containing fluid under a pressure that is to be measured has such a low compliance as to prevent expansion or contraction of the base of the dome resulting from changes in its temperature from causing the diaphragm of a transducer coupled thereto from buckling.

Claims

1. A pressure dome for communicating blood pressure to a transducer, comprising

a base,

a wall having a foot being attached to said base so as to form a cavity,

a membrane adhered to the top of said wall so as to close said cavity,

ports communicating with said cavity,

said wall having such low compliance that most of the radial forces caused by the base expanding or contracting are not transmitted to its top.

2. A pressure dome as set forth in claim 1 wherein said wall is made of polycarbonate.

3. A pressure dome as set forth in claim 1 wherein said wall is made of flexible material.

4. A pressure dome as set forth in claim 1 wherein said wall is comprised of polycarbonate and is 0.025 inch wide and 0.106 inch high.

5. A pressure dome as set forth in claim 1 wherein the ratio of the height of the wall to its thickness is between 10 and 2.5 and the modulus of elasticity in bending of the material from which the wall is made is between 0.15×

10⁶ and 0.7×

10⁶ psi.

6. In combination,

(a) a pressure dome comprising a base,

a wall having a foot, its foot being sealed to said base so as to form a cavity,

ports communicating between said cavity and respective points outside the dome, and

a membrane adhered to the top of said wall so as to be close said cavity,

(b) a transducer having a pressure sensitive surface in contact with said membrane, and

(c) means for holding said transducer and dome together so as to establish a predetermined force of 2 to 8 pounds between said membrane and said pressure sensitive surface, the static coefficient of friction between said membrane and said pressure sensitive surface being between 0.5 and 0.2,

the compliance of said wall being such that, when changes in temperature of between 59°

F. and 104°

F. occur in fluid contained in said cavity or in the air temperature, the top of said wall remains stationary with respect to said pressure sensitive surface.