Automated method for simultaneous bubble detection and expulsion

Patent metadata

Field	Value
Publication number	US-9486589-B2
Application number	US-201414528771-A
Country	US
Kind code	B2
Filing date	Oct 30, 2014
Priority date	Nov 1, 2013
Publication date	Nov 8, 2016
Grant date	Nov 8, 2016

Abstract

A method and apparatus for detecting and removing air from a syringe containing a volume of liquid and a volume of gas is described. The method includes moving a piston in the syringe to expel gas through an orifice of the syringe, sensing a movement of the piston in the syringe, and determining when the volume of gas is expelled from the syringe based on a change in the sensed movement. Moving the piston may include applying oscillating force to the piston using an electromagnetic actuator, and displacement and speed of the piston during each oscillation may be sensed. Determining when the volume of gas is expelled may be based on a change in the sensed movement of the piston during one or more oscillations of the piston or based on a comparison to a given reference value.

First claim

What is claimed is:

1. A method of automatically detecting and removing air from a syringe containing a volume of liquid and a volume of gas, the method comprising:
with an actuator controlled by a controller, applying oscillating force to move a piston in the syringe to expel gas through an orifice of the syringe;
sensing a pattern of oscillations of the piston in the syringe and electrically communicating the pattern to the controller;
in the controller, determining when the volume of gas is expelled from the syringe based on a change in the sensed pattern of oscillations; and
stopping movement of the piston upon determining that the volume of gas is expelled from the orifice.

2. The method of claim 1 , wherein applying the oscillating force to the piston further includes applying at least one of the following in alternation to the piston: a positive and a negative force, a positive and a zero force, and a first positive force and a second positive force, and wherein determining when the volume of gas is expelled from the syringe is based on a change in the sensed pattern of oscillations of the piston during one or more oscillation or based on a comparison to a given reference value.

3. The method of claim 1 , wherein sensing the pattern of oscillations of the piston includes sensing a displacement of the piston, and wherein determining when the volume of gas is expelled from the syringe is based on a change in the sensed displacement of the piston.

4. The method of claim 3 , wherein sensing the displacement of the piston includes sensing a forward displacement of the piston for each oscillation, and wherein determining when the volume of gas is expelled from the syringe is based on the sensed forward displacement of the piston.

5. The method of claim 3 , wherein sensing the displacement of the piston includes sensing a backwards displacement of the piston for each oscillation, and wherein determining when the volume of gas is expelled from the syringe is based the sensed backwards displacement of the piston.

6. The method of claim 1 , wherein sensing the pattern of oscillations of the piston includes sensing a speed of the piston, and wherein determining when the volume of gas is expelled from the syringe is based on a change in the sensed speed of the piston.

7. The method of claim 6 , wherein sensing the speed of the piston includes sensing a forward speed of the piston during each oscillation, and wherein determining when the volume of gas is expelled from the syringe is based on the sensed forward speed of the piston.

8. The method of claim 7 , wherein sensing the speed of the piston includes sensing a backwards speed of the piston during each oscillation, and wherein determining when the volume of gas is expelled from the syringe is based on the sensed backwards speed of the piston.

9. The method of claim 1 , wherein the volume of liquid further includes a plurality of bubbles, the oscillating force applied by the actuator aggregating at least a portion of the plurality of bubbles into the volume of gas.

10. The method of claim 1 , wherein sensing the pattern of oscillations of the piston further includes sensing a forward speed of the piston, and wherein determining when the volume of gas is expelled from the syringe is based a sensed decrease in the forward speed of the piston.

11. The method of claim 1 , wherein determining when the volume of gas is expelled from the orifice includes determining that at least a portion of the volume of liquid is expelled through the orifice.

12. The method of claim 1 , wherein moving the piston in the syringe further includes controlling a force applied by an electromagnetic actuator to the piston as a function of the sensed pattern of oscillations of the piston.

13. An apparatus for detecting and removing air from a syringe, the apparatus comprising:
said syringe including a piston and an orifice, the syringe having a volume of liquid and a volume of gas disposed in the syringe between the piston and the orifice, the volume of gas being adjacent to the orifice;
a position sensor adapted to sense a pattern of oscillations of the piston in the syringe;
an actuator adapted to apply an oscillating force to move the piston in the syringe; and
a controller responsive to the position sensor, the controller causing the actuator to move the piston and drive gas from the volume of gas through the orifice, the controller determining when the volume of gas is expelled from the syringe as a function of a change in the sensed pattern of oscillations of the piston and stopping movement of the piston upon the determined that the volume of gas is expelled from the orifice.

14. The apparatus of claim 13 , wherein the actuator is a bi-directional Lorentz-force electromagnetic actuator.

15. The apparatus of claim 13 , wherein the oscillating force applied to the piston by the actuator includes at least one of the following: a positive force and a negative force, a positive and a zero force, and a first positive force and a second positive force, and wherein the controller determines when the volume of gas is expelled as a function of a change in the sensed pattern of oscillations during one or more oscillations of the piston or as function of the sensed pattern of oscillations as compared to a reference value.

16. The apparatus of claim 13 , wherein the position sensor is further adapted to sense displacement of the piston, and wherein the controller determining when the volume of gas is expelled from the syringe is a function of the sensed displacement.

17. The apparatus of claim 16 , wherein the position sensor is further adapted to sense forward displacement of the piston for each oscillation, and wherein the controller determines when the volume of gas is expelled as a function of the sensed forward displacement.

18. The apparatus of claim 16 , wherein the position sensor is further adapted to sense backwards displacement of the piston for each oscillation, and wherein the controller determines when the volume of gas is expelled as a function of the sensed backwards displacement.

19. The apparatus of claim 13 , wherein the position sensor is further adapted to sense speed of the piston, and wherein the controller determining when the volume of gas is expelled from the syringe is a function of the sensed speed.

20. The apparatus of claim 19 , wherein the position sensor is further adapted to sense forward speed of the piston during each oscillation, and wherein the controller determines when the volume of gas is expelled as a function of the sensed forward speed.

21. The apparatus of claim 19 , wherein the position sensor is further adapted to sense backwards speed of the piston during each oscillation, and wherein the controller determines when the volume of gas is expelled as a function of the sensed backwards speed.

22. The apparatus of claim 13 , wherein the volume of liquid further includes a plurality of bubbles, the oscillating force applied by the actuator aggregates at least a portion of the plurality of bubbles into the volume of gas.

23. The apparatus of claim 13 , wherein the position sensor is adapted to sense a forward speed of the piston, and wherein determining when the volume of gas is expelled from the syringe is a function of a decrease in the sensed forward speed of the piston.

24. The apparatus of claim 13 , wherein the controller is further configured to stop movement of the piston upon the det

Assignees

• Massachusetts Inst Technology

Inventors

• Hunter Ian W
• Modak Ashin P

Classifications

• A61M5/36 Primary

  with means for eliminating or preventing injection or infusion of air into body (dialysis systems, blood oxygenators A61M1/14; haemofiltration equipment A61M1/34; {automatic tube cut-off A61M39/281}) · CPC title

• A61M5/16859

  Evaluation of pressure response, e.g. to an applied pulse · CPC title

• G01P3/02

  Devices characterised by the use of mechanical means · CPC title

• Y10T137/2931

  Diverse fluid containing pressure systems · CPC title

• A61M5/3146

  Priming, e.g. purging, reducing backlash or clearance · CPC title