Air-in-line sensor

• US 5,177,993 A
• Filed: 07/22/1991
• Issued: 01/12/1993
• Est. Priority Date: 07/22/1991
• Status: Expired due to Term

• Current Assignee: Carefusion 303 Incorporated (Becton, Dickinson & Co)
• Original Assignee: Ivax Corporation (Teva Pharmaceutical Industries, Ltd.)
• Inventors: Beckman, Kenneth A., Dikeman, James E., Finburgh, Simon E.
• Primary Examiner(s): Williams, Hezron E.
• Assistant Examiner(s): ROSKOS, JOSEPH
• Application Number:
  US07/733,310
• Time in Patent Office: 540 Days
• Field of Search: 73/19.03, 73/19.1, 73/600, 73/632, 128/DIG. 13
• US Class Current: 73/19.03
• CPC Class Codes: A61M 39/08 Tubes; Storage means specially adapted therefor
• CPC Class Codes: A61M 5/14228 with linear peristaltic action, i.e. comprising at least three pressurising members or a helical member
• CPC Class Codes: A61M 5/365 Air detectors A61M5/1684 takes precedence; in extracorporeal blood circuits A61M1/3626
• CPC Class Codes: G01N 2291/02433 Gases in liquids, e.g. bubbles, foams
• CPC Class Codes: G01N 2291/102 one emitter, one receiver
• CPC Class Codes: G01N 29/032 by measuring attenuation of acoustic waves
• CPC Class Codes: G01N 29/22 Details , e.g. general constructional or apparatus details
• CPC Class Codes: G01N 29/28 providing acoustic coupling , e.g. water impedance matching G10K11/02
• CPC Class Codes: Y10S 128/13 Infusion monitoring

Abstract

An air-in-line sensor is provided comprising an adapter for insertion in the fluid line and a sensor housing. The adapter is semi-compliant and includes convex-shaped acoustic coupling surfaces for engaging the straight and rigid transducer sensing walls of the housing. The convex surfaces of the adapter have a larger diameter than the distance between the housing sensing walls and an interference fit results. Due to this interference fit, the shape of the coupling surfaces, the varying thicknesses of the adapter walls and the difference in compliance of the materials of the adapter and the housing, a more uniform contact pressure profile is provided. The upper part of each sensing channel wall in the housing includes a ledge which wipes contaminants from the coupling surfaces of the adapter as it is inserted into the sensor channel of the housing. The inner passage of the adapter in the sensing section is tapered and this shape resists bubbles which may otherwise tend to adhere to the interior surface of the adapter and be detected by the transducers.

Claims

1. A sensor for sensing a fluid line, the sensor comprising:

a fluid line adapter inserted in the fluid line, the adapter having first and second ends and adapted to attach at both ends to the fluid line and having an inner passage which is in fluid communication with the fluid line, the adapter having a coupling segment comprising two coupling surfaces located diametrically opposite each other, the adapter further comprising an orientation tab; and

a sensor housing, the housing comprising;

an indentation which receives the orientation tab of the adapter in a predetermined orientation;

a sensor channel comprising sensing walls which recieve the coupling surfaces of the adapter, the distance between the sensing walls being less than the diameter of the coupling surfaces of the adapter; and

first and second transducers spaced apart across the channel which communicate sensing energy through the adapter.

2. The sensor of claim 1 wherein:

the coupling surfaces are formed on coupling walls of the coupling segment of the adapter and the walls adjoining the coupling walls are support walls;

wherein the support walls are thicker than the coupling walls.

3. The sensor of claim 2 wherein the support walls have a thickness selected to provide a predetermined pressure profile of the coupling surfaces against the sensing walls of the sensor channel.

4. The sensor of claim 1 wherein the adapter is formed of a semi-compliant material while the sensing walls of the sensor channel are rigid.

5. The sensor of claim 1 wherein:

the coupling surfaces of the adapter are convex; and

the sensing walls are parallel and straight.

6. The sensor of claim 1 further comprising a pair of ledges disposed above the sensing walls, the ledges are spaced apart by a distance which is less than the diameter of the coupling surfaces of the adapter, the ledges are adapted to receive the sensing surfaces of the adapter and thereby wipe off contaminants on the adapter during insertion of the adapter into the housing.

7. The sensor of claim 1 wherein the inner passage of the coupling segment of the adapter is tapered.

8. The sensor of claim 7 wherein the proximal opening of the inner passage through the coupling segment is larger than the distal opening of the coupling segment.

9. The sensor of claim 1 wherein the fluid line adapter is inserted in the fluid line in a series arrangement so that an upstream fluid line is connected to the proximal end of the adapter and a downstream fluid line is connected to the distal end of the adapter.

10. The sensor of claim 1 wherein the adapter is formed of a semi-compliant material and the coupling surfaces are convex;

the sensing walls of the housing are formed of a rigid material and are straight;

whereby the coupling surfaces of the adapter are reshaped to conform to the sensing walls.

11. A sensor for sensing a fluid line, the sensor comprising:

a fluid line adapter inserted in the fluid line in a series arrangement so that an upstream fluid line is connected to the proximal end of the adapter and a downstream fluid line is connected to the distal end of the adapter, the adapter having an inner passage which is in fluid communication with the fluid line, the adapter having a coupling segment comprising two coupling surfaces located diametrically opposite each other, the coupling surfaces are formed on coupling walls of the coupling segment of the adapter and the walls adjoining the coupling walls are support walls, the adapter further comprising an orientation tab; and

a sensor housing, the housing comprising;

an indentation which receives the orientation tab of the adapter in a predetermined orientation;

a sensor channel comprising sensing walls which receive the coupling surfaces of the adapter, the distance between the sensing walls being less than the diameter of the coupling surfaces of the adapter; and

first and second transducers spaced apart across the channel which communicate sensing energy through the adapter;

wherein the support walls have a thickness selected to provide a predetermined pressure profile of the coupling surfaces against the sensing walls of the sensor channel.

12. The sensor of claim 11 wherein the inner passage of the coupling segment of the adapter is tapered.

13. The sensor of claim 12 wherein the proximal opening of the inner passage through the coupling segment is larger than the distal opening of the coupling segment.

14. The sensor of claim 12 wherein the adapter is formed of a semi-compliant material and the coupling surfaces are convex;

the sensing walls of the housing are formed of a rigid material and are straight;

whereby the coupling surfaces of the adapter are reshaped to conform to the sensing walls.

15. The sensor of claim 12 further comprising a pair of ledges disposed above the sensing walls, the ledges are spaced apart by a distance which is less than the diameter of the coupling surfaces of the adapter, the ledges are adapted to receive the sensing surfaces of the adapter and thereby wipe off contaminants on the adapter during insertion of the adapter into the housing.

16. A sensor for sensing a fluid line, the sensor comprising:

a fluid line adapter inserted in the fluid line in a series arrangement so that an upstream fluid line is connected to the proximal end of the adapter and a downstream fluid line is connected to the distal end of the adapter, the adapter having an inner passage which is tapered and which is in fluid communication with the fluid line, the adapter having a coupling segment comprising two coupling surfaces located diametrically opposite each other, the coupling surfaces are formed on coupling walls of the coupling segment of the adapter and the walls adjoining the coupling walls are support walls, the adapter further comprising an orientation tab and a positioning ring; and

a sensor housing, the housing comprising;

an indentation which receives the orientation tab of the adapter in a predetermined orientation;

a positioning channel which receives the positioning ring of the adapter to resist longitudinal movement of the adapter in the sensor housing;

a sensor channel comprising sensing walls which receive the coupling surfaces of the adapter, the distance between the sensing walls being less than the diameter of the coupling surfaces of the adapter; and

first and second transducers spaced apart across the channel which communicate sensing energy through the adapter;

wherein the support walls have a thickness selected to provide a predetermined pressure profile of the coupling surfaces against the sensing walls of the sensor channel.

17. The sensor of claim 16 wherein the adapter is formed of a semi-compliant material while the sensing walls of the sensor channel are rigid.

18. The sensor of claim 17 wherein:

the coupling surfaces of the adapter are convex; and

the sensing walls are parallel and straight.

19. The sensor of claim 16 further comprising a pair of ledges disposed above the sensing walls, the ledges are spaced apart by a distance which is less than the diameter of the coupling surfaces of the adapter, the ledges are adapted to receive the sensing surfaces of the adapter and thereby wipe off contaminants on the adapter during insertion of the adapter into the housing.