Osmotic pressure sensing head

• US 4,028,931 A
• Filed: 02/13/1976
• Issued: 06/14/1977
• Est. Priority Date: 02/13/1976
• Status: Expired due to Term

• Current Assignee: Cardio Pulminary Laboratory Research Foundation
• Original Assignee: Cardio Pulminary Laboratory Research Foundation
• Inventors: Bisera, Jose, Weil, Max Harry, Carrington, James Howard
• Primary Examiner(s): Queisser, Richard C.
• Assistant Examiner(s): Roskos, Joseph W.
• Application Number:
  US05/657,837
• Time in Patent Office: 487 Days
• Field of Search: 73/64.3, 23/230 B
• US Class Current: 73/64.47
• CPC Class Codes: G01N 13/04 Investigating osmotic effects

Abstract

An osmotic sensing head for measuring the osmotic pressure of protein molecules in blood, which is of the type that includes a reference chamber for holding saline solution, a sample chamber for holding blood, an osmotic membrane between the chambers, and a pressure sensor coupled to the reference chamber to measure the pressure therein. The sample chamber has a small volume and is provided with an inlet and outlet so that a storage saline solution can be removed and a blood sample introduced by merely flowing the blood sample in through the inlet while allowing the storage solution to pass out through the outlet. The inlet is directed at the membrane at an angle to help wash away material lying on the membrane. The osmotic membrane is held in slight tension by an elastomeric O-ring which presses the membrane against a conical surface.

Claims

1. An osmotic sensing head comprising:

first walls forming a sample chamber for holding a sample fluid;

second walls forming a reference chamber for holding a reference fluid, said reference chamber including a passage with a narrow first end which opens toward said sample chamber and with a second end, said narrow first end being narrower than the area of the sample chamber;

an osmotic membrane disposed over said narrow first end of said reference chamber passage; and

pressure measuring means coupled to said second end of said reference chamber passage;

the narrow first end of said reference chamber passage forming a region in contact with said membrane which is narrower than the region of said sample chamber which is in contact with said membrane; and

the walls forming said reference chamber including a pair of conduits for carrying fluid to and from said sample chamber, at least a first of said conduits having an end angled to direct fluid entering said reference chamber against the portion of said membrane which lies directly over said narrow first end of said reference chamber passage, whereby to flush away debris lying on the portion of the membrane which lies over the narrow end of the reference chamber.

2. The head described in claim 1 wherein:

said narrow first end of reference chamber passage lies under the center of said membrane, and said first conduit end is directed at the center of said membrane.

3. A method for determining the amount of protein molecules in a sample of blood-like material, comprising:

establishing a reference saline solution in a reference chamber that has a narrow end open to a first side of a membrane which permits the movement of saline solution molecules but does not permit the movement of at least some blood protein molecules therethrough, and establishing a storage solution in a sample chamber that is open to a second side of said membrane;

changing the fluid on said second side of said membrane by withdrawing said storage solution from said second side of said membrane and flowing a sample fluid containing blood plasma onto said second side of said membrane;

measuring the pressure of fluid in said reference chamber; and

again changing the fluid on said second side of said membrane by withdrawing said sample fluid from said second side of said membrane and flowing a storage solution onto said second side of said membrane;

said step of again changing the fluid including directing a stream of said storage solution into said sample chamber directly against the membrane portion which lies over the narrow end of the reference chamber, while flowing said sample fluid out of said sample chamber.